Ask the RD: Is Intermittent Fasting Really Helpful For Weight Loss?

Trinh Le, MPH, RD
by Trinh Le, MPH, RD
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Ask the RD: Is Intermittent Fasting Really Helpful For Weight Loss?

Proponents of intermittent fasting say it can help regulate hormones and aid with fast, sustained weight loss. But will it work for you? Here, we explore the idea behind intermittent fasting and whether it’s an effective weight loss strategy.

What is intermittent fasting?

Intermittent fasting is more about when you eat rather than what you eat. A typical plan puts you on a scheduled fasting phase followed by a non-fasting phase. The former is where you may skip meals or eat significantly fewer calories to generate the energy deficit needed for weight loss. This allows more food flexibility and higher calorie goals in the latter phase.

A typical, calorie-restriction weight loss plan encourages a small daily restriction of 250–1,000 calories depending on how much weight you have to lose and how fast you want to lose it. While this may seem like a lot, it’s small compared to the thousands of calories slashed during the fasting phase of an intermittent fasting plan.

Is intermittent fasting effective for weight loss?

Intermittent fasting can be effective for weight loss although it’s not necessarily better than other methods, according to a 2015 review of 12 clinical trials. More recently, a 2017 randomized controlled trial of 100 healthy but obese adults found that after one year, weight loss was comparable between intermittent fasting and daily calorie restriction.

Choosing intermittent fasting over more traditional calorie restriction comes down to individual preference and biology. We are culturally conditioned to eat three square meals with snacks in between, but that doesn’t mean everyone thrives on this schedule. One person may claim skipping a meal gives them more energy while another goes hangry if they miss just one snack. Some people do better on daily calorie restriction because they like an incremental change and regular meals. Others may find daily restriction wears away their willpower, and they prefer intermittent fasting so they can front load their calorie restriction to just a few days.

How to Practice Intermittent Fasting Safely

Intermittent fasting can be a safe choice for weight loss, but it all depends on how you approach it and how your body responds. Fasting is not for everyone and you shouldn’t try intermittent fasting if you are pregnant, diabetic or healing from a traumatic event such as surgery. Critics of intermittent fasting also point out that all this emphasis on restriction can backfire and encourage bingeing and other disordered eating behaviors. Our physical and mental health histories are all different, so if you have trouble deciding whether intermittent fasting is for you, consult a healthcare professional. Generally speaking, though, there’s little evidence to say intermittent fasting isn’t safe for healthy adults who have a bit of weight to lose.

The human body is designed to deal with fasting. It did not evolve to have food every hour of the day. Fasting triggers hormonal changes that are beneficial for your body. When you fast, insulin levels drop, allowing your cells to release stored fat and use it more effectively. Fasting also stimulates a housekeeping process called “autophagy.” With no food around to process, your cells can use that spare time to remove damaged or misfolded proteins. It doesn’t matter if you choose intermittent fasting or daily calorie restriction, fasting for a few hours enables your body to fulfill this important task.

It’s important to note that fasting is not the same as starvation. Going for days without eating or eating a very low-calorie diet indefinitely is not safe.

3 Types of Intermittent Fasting

For those new to MyFitnessPal, daily calorie restriction may be easier since it’s the default setting and it’s no less effective than intermittent fasting. For those interested in giving intermittent fasting a try, here are three popular plans:

1

Alternate-Day Fasting

Also known as “eat stop eat,”  this plan involves fasting on 3–4 non-consecutive days per week. A 24-hour fasting phase is followed by a non-fasting day where you can eat as much as you’d like.

2

Modified Fasting

A 5:2 fasting plan means fasting on two non-consecutive days per week where you eat between 20–25% of your daily calorie needs. On non-fasting days you can eat normally.

3

Time-Restricted Eating

With the Lean Gains and the Warrior Diet, you fast anywhere from 8–20 hours per day. You can eat freely during your non-fasting hours. Scheduling fasting hours overnight can make this plan easier.

THE VERDICT

There’s no one-size-fits-all diet for weight loss. Intermittent fasting can be helpful, but first consider whether it fits into the lifestyle you want to lead. If you try fasting and it’s not for you, cutting calories the old-fashioned way can still help you lose weight. Listen to your body, and pick the plan that works for you. Regardless, don’t forget calorie quality matters, too. As you’re losing pounds, nourish your body with nutrient-dense foods including fruits, veggies, grains, lean proteins and healthy fats.

About the Author

Trinh Le, MPH, RD
Trinh Le, MPH, RD
Trinh is a registered dietitian by day, blogger at Fearless Food RD by night. She loves helping folks develop a better relationship with food, which includes lots of cooking, eating and learning about nutrition. When she’s not snapping mouthwatering shots of (mostly) healthy food, you can find Trinh HIIT-ing it at her local gym. For more, connect with her on FacebookInstagram and Pinterest.

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137 responses to “Ask the RD: Is Intermittent Fasting Really Helpful For Weight Loss?”

  1. -Cool-Daddy- says:

    Wow, I was expecting a scathing article but instead I got an insightful and intelligent written piece. This can’t be mainstream nutritional science yet?

  2. Its very important to know what you are doing, whether it’s beneficial for you or not. It is said that the Intermittent fasting help you to a sustainable weight loss but is it really work. Find your answers on this shared article. Thanks for sharing helpful information on Intermittent fasting, its types, weight loss effects.

  3. Sez says:

    I was also pleased to see that article had a more balanced and informed perspective on fasting. However noticed that decreased levels of insulin sensitivty, decrease in makers for certain cancers and fat decrease around vital organs were not discussed, which is far greater benifit to fasting than just weight loss alone. These added benifits can tip the scales so to speak when looking at the differences between the two methods.

    • Ritz says:

      I also feel like they buried the benefits so far down in the article. And from what I’ve been told, your goal is it keep up your calories and not focus on restricting your calories when you do eat. I do give the author credit for not just slamming the method all together.

    • Holly Brown says:

      As I noted above, the research in 2017 they noted was not on Intermittent Fasting, which the article is based on, it was on alternate day fasting and I didn’t see any notes on if the participants changed their food choices at all. That information wasn’t relevant unfortunately. Alternate day fasting would be hard to do if you are still eating foods that trigger on the “feasting” days.

  4. Christopher Cardenas says:

    You should also see the PBS NOVA documentary on fasting diets to truely understand the benefits of fasting. If you have a family history of cancers, this might be an effective way to end that cycle.

  5. The Best LeChef Style Poster says:

    Why would people be hangry after missing a snack? Maybe it’s that they run on sugar snacks all day, even complex carbs sugar snacks, that give them short energy, then crash these folks. Maybe they could incorporate some timed feeding, like a 16:8 fast:feed and regain some control of their insulin.

    And that leads to my second complaint? Why should diabetics avoid fasting, when it lowers their blood sugar and insulin? Are we talking folks with T2DM or type 1? Either way, carb reduction combined with IF will help those folks use less exogenous insulin, and have more control over their blood sugar, and be more healthy. Or, they could just shoot a bolus of insulin and eat as much cashew based non-dairy ice cream substitute as they can fit.

    • LarkspurM says:

      Thank you for saying all of this. As a type 1 diabetic who has eaten keto and engaged plenty of IF I find it so deeply annoying when articles like this state that fasting is not for diabetics as a general statement. That is so old school!!

    • Susie Lee says:

      For some diabetics it can be a problem. My sister in law is an example, if she does not eat a small amount about every threeish hours, she gets light headed. She is not overweight though.

      • The Best LeChef Style Poster says:

        What is her carbohydrate intake like?

        • Susie Lee says:

          Very low.

          • The Best LeChef Style Poster says:

            Surprising. Maybe inadequate fat intake. Maybe genetically prediposed… who can say… most folks see great reduction in hunger signalling with LCHF.

          • Susie Lee says:

            Hunger is not a problem, she is doing great. I think there is a disconnect on my post. Likely the way I worded it.

            she is doing great, so she has no need to change it.

      • Holly Brown says:

        Susie Lee, if your sister is eating the typical diabetic diet, she would need to do that. But if she were to cut out grains, starches and all processed sugars… it is possible that she may be healed from her diabetes (unless she is a Type 1) and she would be able to do the intermittent fasting. Have her look for the video’s on reversing diabetes on YouTube if she is interested.

        • Susie Lee says:

          She has come off all meds following her diet of eating several small meals a day with a small snack close to bedtime, and a small snack upon rising, I would never advise her to do anything but what she is doing.

          She was never really very heavy, but following her drs orders in terms of diet, she is off her diabetic meds and has lost enough weight to be considered on the slim side.

          I appreciate the info, but I don’t think she is going to mess with success.

          • SarahJ89 says:

            Stick to your guns, Susie. If it ain’t broke, don’t fix it. Your SIL’s approach is working for her. That’s what matters. Sounds as if she has a good MD, too.

    • sterlingVT says:

      I fast daily (16:8) everyday and I’m a diabetic. Only side effect I’ve had is weight loss and being able to reduce the amount of daily insulin I take from 32 units to only 6 ( and lower blood sugar)

  6. Windtalker says:

    “Going for days without eating or eating a very low-calorie diet indefinitely is not safe.”

    Completely ridiculous. People have been fasting “for days” for centuries. I’m regularly stupefied by the nonsense published by “RDs.” No wonder half the nation is diabetic or prediabetic.

    • Lori says:

      I guess it would be depended on the definition of “days.” Anything more than 3 would be unsafe for most people. I get tired of the argument that people have been “fasting for days for centuries.” What happened centuries ago does not necessarily apply today. You have heard of evolution right?

      • LarkspurM says:

        fasting for 3 days is unsafe? where do you get that from? it is true that going with water for more than 3 days can be deadly, but not eating?

        • Lori says:

          Where did I say that fasting for 3 days is unsafe? I said “anything more than 3 would be unsafe for most people.” Maybe that extreme fasting is affecting your ability to read comprehensively. Where do I get that fasting for more than 3 days is unsafe? Harvard medical, Mayo Clinic, Healthline to name a few. Also, if fasting for long periods of time, you shouldn’t be engaging in exercise, unless you want to end up having reconstructive surgery on your face when you land on it.

          • Tina says:

            In your first post, I quote, “Anything more than 3 would be unsafe for most people.”

            Your body has to reach ketosis to get results

          • Lori says:

            And again I ask, where did I say “fasting for 3 days is unsafe”? As you point out, I said “fasting for ‘MORE than 3 days would be unsafe for MOST people.’” (Emphasis added)

          • Bart says:

            Your point is ridiculous. If the body was so weak as to require food constantly, we would have all died off years ago, before McDonald’s and packaged food was invented.

        • Tina says:

          I have a trainer that does it 7 days a week, everyone is different

      • S says:

        It’s not unsafe to fast for more than 3 days if you know how to refeed. I’ve seen videos of people who have done 30 day water fasts due to health issues and go to the doctor to find they are no longer pre diabetic lost tremendous weight(obviously<<no food) got control of their cholesterol and blood pressure. Follow up videos show that their pallets become way more refined and highly sensitive to sugar so they don’t reach for the same unhealthy snacks they usually would have and they lead a way more healthy energy filled life.

      • steve poling says:

        Dr. Jason Fung has been practicing medicine in Toronto much more recently than centuries ago. I recommend his book, “The Obesity Code” and his several YouTube videos advocating fasting for the benefits metabolic and otherwise describe in this article. If you are in tenuous health, your doctor should advise every course of action. Conversely, healthy people commonly fast overnight for blood tests and procedures such as colonoscopies. Each night we go several hours without feeding, and if you skip breakfast you’re in intermittent fasting territory.

      • Windtalker says:

        Ridiculous.

      • Damo says:

        Centuries is not really a lot of time for evolution o have altered the human body in such a way.

      • John Furr says:

        LOL… LOTS of people are still fasting for ‘day’s NOW. No you haven’t evolved away from being able to fast. Your body thrives on it.

    • Tina says:

      Its not days, if you actually know IF and its benefits and everything that goes with it, you only fast for 16hrs and eat 8. You get all your calories in, you gotta eat less then your daily BMR to actually lose weight. A lot of countries around the world exp 3rd world ones do fasting all the time cause they can only afford to do one meal a day.

      IF has helped reverse diabetes and other health issues, check out “Six pack abs” on youtube and facebook they have a crap ton of videos that explain IF and its benefits, I have a trainer that does it 7 days a week. There is a ton of info out there, even doctors have recommended it to their patients.

      • SarahJ89 says:

        I do the 5-2 thing. IF every day would wear upon me the same way traditional weighing/measuring daily plans do.

        On my fast days I dont’ feel deprived. I feel as if I’ve made a one-day choice. Doing IF every day would quickly wear me down.

        My personality isn’t steady and regular, though. I’m a sprinter, not a marathoner. My sweetie is an accountant. He’s a real steady Eddie marathoner type. I’m guessing if he did it the daily IF would work for him in a way it wouldn’t for me.

        • Tina says:

          my husband works in a hospital for 12hrs a day so, it wouldn’t work for him since hes on his feet and needs to eat.

          I go to wrestling school and train at the gym 6 days a week every week, reason I had to stop for awhile when i was getting weak 2hrs before I got to eat. I can’t do it everyday. When i start up again i will try every other day 🙂

          • SarahJ89 says:

            Oh god yes, Tina. I’ve worked in hospitals. No way would that work for him.

            I’m a total couch potato. It’s nothing short of a miracle that I’ve managed to lose any weight at all. But I feel better enough now to consider going to a pool/fitness centre in a hotel about a mile from my home.

            Every other day might well work for you with your schedule. Different strokes…

          • Tina says:

            You can do it!
            I got made fun of in high school for being fit and doing track/sports and weight lifting. I graduated back in 2000.
            I packed on 250+lbs after highschool in 3 years.
            3 years ago for the 3rd time I got back on track working on my self esteem and confidence and getting to the gym.
            I had a lot of ups and downs but I am now down 215lbs and 70 inches in my waist.
            Never thought at 36 years old I would of got into wrestling school, but I been training doing that for 4 months now, I feel like I am 20 again =D

          • SarahJ89 says:

            Massively impressed with your whole story. Did you gain so quickly after high school because you stopped the athletics? Or was it world-class extended senior panic? I spent my last year of high school barely able to maintain 95 pounds because (I now realise) I was so anxious I couldn’t eat most of the time. Later in life I went the other way and ate when I was anxious. Neither one is good. Neither one feels good.

            I was underweight all my life until my late twenties. I think my thyroid was beginning to crash around then. I piled on 70 pounds in my early 30’s, went to WW and over time (a great deal of time) lost the 70 I’d put on. Eventually I got diagnosed with hypothyroidism.

            I put about half of the 70 back on. Over time I’ve noticed my “acceptable” (to me) weight has crept up in ten pound increments so I ended up gaining back about 2/3 of those 70. Ugh.

            I simply cannot live a lifetime of daily weighing and measuring and thinking about my intake. Just cannot do it. On the other hand, there’s no way I want to live fat. I stumbled across the 5-2 plan and have lost a stone, which is great. But I seem to be a bit stuck so I’m going to try segueing over to the IF plan you’re describing.

            I did learn the last time I was on WW that I can eat ONE serving of whole grain carbs per day. No more than that if I want to lose, just doesn’t work for me.

            Next stop is: move more.

          • Tina says:

            I did gain quickly cause I turned to fast food and got lazy.
            I would pick up 3 whoppers from Burger king with a large fry and soda and watch tv all night.
            Order a whole pizza and eat the whole thing in one sitting, or get a bucket of KFC chicken and eat that.
            That’s just the tip of eating to drown my pain of being bullied for being in shape.
            It all started after I graduated.

            When i went into high school I was only 95lbs, graduation I was at 135-140lbs, but again I put on all muscle during that time.

            So where I grew up in Canada unless you were model skinny or overweight no guys liked girls that were fit.

            Sounds like your body type is like mine, my trainers/food coaches put me on high protein (about 1g per day per lb I weigh, but i can’t get that high some days even with protein shakes) and low carb (60g or less mainly veggies) and high fats.

            Kinda like Paleo/Keto a mix of the two … seems to be working.

            Sounds like you had a tough time, i have a few friends that have thyroid issues, its not easy, even have friends that have PCOS.

            You got this! Just hang in there!

    • Damo says:

      I fast every day–not eating until noon and stopping by 8 pm. This gives me a big window where I can eat (but still count calories for that window).

      Occasionally I go on a very low calorie diet ( a few hundred calories a day for a few weeks or several days with no calories). When I do that, I am cranky for about 2 days. Than I forget all about food and have plenty of energy. Since starting this, my blood pressure is down, my A1C is down, my heart rate is normal. I feel good and full of energy.

      Also, when I come off a fast, I forget about all the foods that may have been tempting me prior to the fast. I am just happy and satisfied with a salad of greens and some fruit, because it is like I am tasting food for the first time, I don’t really need ice cream or anything else.

      I highly recommend fasting (just if you are going to do it for an extended period, have medical supervision since there can be complications).

  7. Mama loves to cook says:

    I have been intermittent fasting every day since May. All my eating is within an 8 hour timeframe. I’ve dropped 30 pounds. A ton more energy. It really does work.

    • LESLIE C. says:

      Curious, do you have coffee in the am? Thanks and great job, congrats!!

      • Carlos Danger says:

        I drink a large cup of black coffee every morning as it will not break your fast. I have been IF for a year and lost 53 pounds (mostly fat).

        • Thales Nemo says:

          Actually only instant coffee does not break a fast since it has no calories. Coffee brewed from grounds does have calories so by definition it will break a fast .

          • Tina says:

            Look into the guy that does SIX PACK ABS, he says black coffee is fine, green tea as long as your having them with NO sugar milk etc. No one drinks instant coffee anymore it tastes like butt

          • Tina says:

            see my comment from 4 days ago, all research says black coffee is fine

          • Bradley Reed says:

            Wrong. Instant coffee is processed using a number of chemicals and will cause inflammation. Black coffee does not trigger insulin so will not break your fast.

          • Stephen Hrutka says:

            Agree with Bradley

      • Tina says:

        Only thing your allowed to drink when your fasting is green tea, black coffee, sea salt water, regular water and I can’t remember the other drink. Also there is a fasting drink with apple cider vinegar, lime juice, cream of tartar, and i can’t remember what else you have 2 hours before your fast window is up. Check out “Six pack abs” on youtube and facebook, hes got a ton of videos on IF and the recipes for what you can have.

        • SarahJ89 says:

          Ah, two hours. I’ll try that tomorrow. Means I shut down the cook tent an hour or so earlier tonight, but that’s entirely doable.

          • Tina says:

            good luck, let me know how it goes!

          • SarahJ89 says:

            It’s almost 9:00 now. That will be 14 hours. Good for today.
            It certainly makes me appreciate that cup of tea!
            Thanks for your support.
            What are you doing now for sports? You mentioned getting back into wrestling. I’m an old lady so I know I need to start doing some simple weight lifting (or whatever the proper term is). I probably should be careful as my joints aren’t what they used to be.

          • Tina says:

            Your welcome!
            I am 36, never in my life at my age would I dreamed of getting into wrestling but I am lol.
            I just do wrestling and weight lifting now and very little to no cardio.
            I weigh 235lbs but my doctors and friends tell me I don’t look it, that’s because I carry more muscle =)
            High school I used to do track and sports.
            I grew up in Canada so hockey was big as well as football and other stuff 🙂
            I did it all though lol

        • Annie says:

          Again, Tina, you’re giving rules about Keto, but that is not the same as IF. The Keto diet if a form of IF, but is much more restrictive. I’m living proof that one can lose weight without going to the extremes of Keto.

          • Tina says:

            As I said if you look up IF through six pack abs on youtube his videos are about IF and what you can have during the window of IF, what I listed ARE those things, for IF, NOT KETO! Please read up and learn these things.

      • SarahJ89 says:

        I do 5-2 fasting. I have several cups of regular old black tea with milk every morning, including my fast days. I’m Irish, not about to give up my tea for anything.

        It hasn’t impeded my weight loss. Being unable to have my morning tea would greatly impede my ability to stick to the program. In the end, sticking to a program that’s working is my prime consideration.

        • Tina says:

          milk breaks ketosis and your fast, so you wont get the full results. Black Tea, Black Coffee, Green tea, sea salt water, regular water are the only things you can have during fasting hours.

          • SarahJ89 says:

            I’m more than willing to make the trade off. I’ve lost a stone so far and am quite happy with the regimen I’m on. I would not be happy at all without my morning cuppa. Not at all. Sustainability is my prime consideration, after years of plans that work but drain the life outta me.

          • Tina says:

            i get that, reason i can’t give up coffee, but i did give up creamer. I ended up losing 12lbs in 3 weeks and 4 inches off my waist. I am down a total of 215lbs now (15 stone roughly)

          • SarahJ89 says:

            Yeah, I think I could give up cream in coffee. Except I don’t drink coffee.

            I’m toying with the idea of at least having a glass of seltzer water (to which I am totally addicted) instead of tea for the first hour or so. I’m intrigued with this 12+ hour business. It definitely has taken me a looong time to lose the stone.

            You’ve inspired me now, Tina. Tomorrow will start out with seltzer water for at least an hour.

            How are you adjusting to the weight loss? It can be such an enormous change in your life. Good on you for keeping on. I’m really finding the 5-2 plan the first sustainable approach ever.

            Thanks for your encouragement and information.

          • Tina says:

            I tried to post my comment with some videos for you but MFP needs to approve it >_>

            Here is what i said though without the video links

            I drink sparkling water too, its my go to now instead of soda.
            As carbs are reduced and fat is increased, the body enters a metabolic state called ketosis.
            Which your body starts turning fats into ketones, which are molecules that can supply energy for the brain it lowers your insulin levels, and your body produces ketones and increases fat burning.
            Because it’s taking that fat and putting it into energy.
            That’s why most fast for 16hrs because that is a good window for your body to reach the peak for ketosis.
            Reason they tell you only black coffee, black tea, green tea, sea salt water and other things I mentioned (not sure on sparkling water though, never looked into that one cause I don’t drink it when I fast).
            It sucks sometimes cause you get soooo hungry.

          • Bradley Reed says:

            12 hours is NOT intermittent fasting – it is a normal nighttime. Intermittent fasting is limiting your eating to small windows of time in your day. Best results are to eat one meal per day. It is also something that must be a lifestyle change – if you stop intermittent fasting in six months your body will naturally return to it’s previous set weight. Once you’re in the habit it is VERY easy to maintain but it will take a few weeks to stop noticing pangs of hunger at your old habitual eating times. Well worth the effort – I went from 90+Kg and now easily maintain 70Kg.

          • Annie says:

            This woman has said she’s been successful on IF, doing it her way. Why argue? I did IF with no concern for time (other than a 24-hour day) and it worked fine for me. I also can tell you that the claim that once you stop IF you’ll return to your previous weight is not true. I lost 25+ pounds on IF four years ago and I’ve kept all but 5 or so off.

          • Tina says:

            you have to do things correctly to get the full benefit, she got some success from what she had done yes, but to go above and beyond to get more success she does it the 100% correct method she will get better results. Her and I already and spoke as you can see, so she is trying the correct method to see how things work better. You learn from others and take or not take the advice given.

          • Damo says:

            How long did 215 take you?

            I am at 80 lbs in 6 months but have 50 more to go and the last month saw markedly decreased loss. I am hoping that I can be at my goal within a year of my start.

          • Tina says:

            I had many set backs its been 3 years 3months I been on this journey.

            Here is why..

            I been working out since May 2015, first year I just went walking around my neighborhood 6 days a week, then invested into a treadmill once the weather got hot. August 2016 I joined Planet Fitness and got with one of their trainers (i was down about 130lbs at this point)

            I tossed the scale aside like the trainer said, my eating was good I was doing real good til I got with PF’s trainer. He was telling me to eat more, I thought hes the trainer maybe he knows something I don’t. He had me lifting weights for a hour 3 days a week with 30mins of cardio on top of it then 2 days a week 60mins of cardio.

            By Jan 2017 I had gained 60lbs back listening to him, how I found out was around Christmas I told my husband I didn’t feel any different, that I felt heavier, pulled out my scale and there it was. So I went on my own again started doing my husbands workout routine from his army days. One day chest, then back, then bi’s, then tri’s then legs and a conditioning day.. in 6 months I lost the weight I gained thanks to that trainer. Joined a new gym got a food coach and trainer for a couple months, lost more weight.

            So yeah, not all trainers know stuff lol.

          • Louise Johnson says:

            Well, according to my doctor, who you earlier claim is who I should be listening to, I cane have coffee or tea with cream in it, or bone broth, and it won’t break my fast, so I believe I’ll tske her word for it

          • Bradley Reed says:

            Cream and milk are VERY different. Heavy cream doesn’t trigger insulin to the degree elements in milk do trigger insulin. Intermittent fasting is actually all about triggering the growth hormone insulin – those small details can make a big difference.

          • Tina says:

            Waiting on MFP to approve the link to my post for the article but I copied/pasted this so you can see it is true that ANY calories will break a fast.

            In general, when fasting it is best not to consume calories of any kind, in order to stay in a fasted state. This means sticking to water, black coffee and unsweetened tea. Adding salt to your water can be beneficial as it will help you replenish your electrolytes and will not break your fast.

            Anything else – fat, heavy whipping cream, an egg, a few almonds, etc. – will break your fast, as energy in the form of food or a drink will raise your insulin (albeit minimally, if the amount is small) and will put you out of your fasted state.

          • Tina says:

            Go ahead, I had my doctor, trainer, food coach all tell me different 😛

          • Tina says:

            Waiting on MFP to approve the link to my post for the article but I copied/pasted this so you can see it is true that ANY calories will break a fast.

            In general, when fasting it is best not to consume calories of any kind, in order to stay in a fasted state. This means sticking to water, black coffee and unsweetened tea. Adding salt to your water can be beneficial as it will help you replenish your electrolytes and will not break your fast.

            Anything else – fat, heavy whipping cream, an egg, a few almonds, etc. – will break your fast, as energy in the form of food or a drink will raise your insulin (albeit minimally, if the amount is small) and will put you out of your fasted state….

          • Tina says:

            Here is something else from the article I am still waiting for MFP to approve the comment with the link but here:

            What To Eat and Drink During Intermittent Fasting
            Safe List

            Water
            Black coffee
            Green tea and other pure teas (no added sugar/fruit)
            Sparkling beverages (such as carbonated water with no calories)

            No-Go List

            Bulletproof coffee (BPC)
            MCT oil and MCT Powder
            Coffee or tea with heavy cream, creamers, butter, coconut oil or sugar added
            Bone broth and collagen powder
            BCAAs and other protein powders
            All common whole foods

          • Annie says:

            Tina, you seem to be posting about a Keto diet, but the article is about IF, which isn’t necessarily about ketosis. You say that it’s impossible to lose if you use any milk products during a fast, but I lost 25+ pounds while putting half-and-half in my coffee every morning and not paying any attention to the timing of meals, except to try to space them far enough so that I didn’t use up my calorie allotment (around 500 calories) too soon in the day. Everyone is different and a Keto diet may have worked wonders for you personally, but that doesn’t mean that nobody can lose weight using other methods.

          • Tina says:

            again look up the 6 pack abs and watch his videos on IF, what I said and wrote here are still things I got from his IF videos, go watch them for yourself.

          • Stephen Hrutka says:

            Research shows anything under 50 calories doesn’t stop ketosis….his tea is fine.

          • Thales Nemo says:

            Please post references .

          • Tina says:

            Here you go 🙂
            yes it will break fast

            Waiting on MFP to approve the link to my post for the article but I copied/pasted this so you can see it is true that ANY calories will break a fast.

            In general, when fasting it is best not to consume calories of any kind, in order to stay in a fasted state. This means sticking to water, black coffee and unsweetened tea. Adding salt to your water can be beneficial as it will help you replenish your electrolytes and will not break your fast.

            Anything else – fat, heavy whipping cream, an egg, a few almonds, etc. – will break your fast, as energy in the form of food or a drink will raise your insulin (albeit minimally, if the amount is small) and will put you out of your fasted state.

          • Bart says:

            It just depends how quickly you are going, how much you need to lose, and when you wanna get there. I’m not cutting cream or half and half from my coffee, equal too, and it probably slows me some. Big deal, Im still losing weight, and I only have about 20lbs to go. Biggest thing is, after listening to the conventional wisdom about high sugar eating (what they REALLY should call it!) I now know how to maintain my weight.

            Nobody is saying cream is gonna help, but how much is it really hurting? Just don’t use the flavored stuff with canola oil plan kernel oil, and sugar.

          • lafe harris says:

            Just switch milk for heavy whipping cream and you stay in Ketosis

      • Damo says:

        I have ied tea with lemon or lime added. It is a miniscule amount of sugar (two limes over one gallon of tea, then divided into one cup doesn’t seem like much).

        I used to drink coffee, but now I feel like the anxiety is too high since I have begun dropping the pounds.

    • Susie Lee says:

      I have recently lost a little over twenty pounds doing that. I am mostly eating healthy, but I occasionally slip up. I have found that as long as I stop the slip up, and don’t eat away the evening, it does not stop my weight loss much.

      I limit my eating to between ten am and seven pm. I used to eat most of my calories in after dinner snacking, but if I avoid that by doing the IT plan; it seems to work.

  8. bsjone says:

    This article is just one more example of why I’m considering deleting the My Fitness Pal app. The inundation of these generalized articles that do nothing more than scare the uneducated and keep them from looking into different solutions is very irresponsible. Countless studies show that IF is beneficial. Of course, with anything, if someone does something haphazardly, they will get bad results. For example, doing IF and then eating sugar and other bad foods during your eating window, you will get adverse effects. Please stop publishing these generalized articles.

    • Lori says:

      You are being unfair. This is not a scientific publication. It is geared to laypersons and therefore needs to be general in nature. There is nothing whatsoever in this article that should “scare the uneducated.” It specifically encourages investigating options. Sounds like you want MGP to practice medicine.

      • The Best LeChef Style Poster says:

        I’d like MFP to stop pretending that no one does LCHF or has success with it. I’d like them to look at carb reduction without dietitians, who were trained in curricula funded by cereal companies.

        MFP works for me, jankily, but I don’t do any fasting beyond as 13/11 cycle, with the bulk of the 13 being asleep. It’s passive aggressive to LCHF dieters, treating fat like a ceiling and scolding anytime you have ten grams of saturated fat at a meal.

        The program is hostile to people who do OMAD and EF protocols.

        It does what I need it to, as long as I ignore its jibes and complaints. The continual parade of nutrition articles that are either hostile to LCHF or pretend it doesn’t exist… not serving my needs.

      • Susie Lee says:

        True, it is why they offer warning that they are not medical folks. Fact is for some diabetics IF could be dangerous. So they will of course cover themselves.

    • Mia Wright says:

      Agreeed!

    • Tina says:

      You want great sources of info on IF, go to youtube or facebook and look up “Six Pack Abs” that guy knows his stuff 🙂

    • SarahJ89 says:

      I use MFP to chart my weight. Also, sometimes I use it to track my 600 calories on my fast days.

      It’s a gas to look at my report, see the jig-jags going up and down–but over time decline steadily.

      So I still find it useful. I just ignore their gasps of dismay on the days I’m tracking my 600 calories. I don’t use it on non-fast days since the point of my approach is to stop with the daily obsession. Fasting gives my body a louder voice so I’m now able to pay better attention to what it needs (rather than what my brain or mouth want) on the non-fast days. I find sugar in particular, is almost repulsive to me after a fast day.

    • SarahJ89 says:

      I use MFP to chart my weight. Also, sometimes I use it to track my 600 calories on my fast days.

      It’s a gas to look at my report, see the jig-jags going up and down–but over time decline steadily.

      So I still find it useful. I just ignore their gasps of dismay on the days I’m tracking my 600 calories. I don’t use it on non-fast days since the point of my approach is to stop with the daily obsession. Fasting gives my body a louder voice so I’m now able to pay better attention to what it needs (rather than what my brain or mouth want) on the non-fast days. I find sugar in particular, is almost repulsive to me after a fast day.

  9. Tim Del Carlo says:

    You people are argumentive, calm down. I have tried IF on 16:8 on the advice of a real dietician and do not eat sugar, carbs (complex/Bread/flour based products) I stick with above ground veggies like broccoli zucchini spinach peppers seasoned with garlic, I lost 35lbs and I am no longer pre-diabetic.. great energy feel great

  10. xGryfter says:

    I’ve been intermittent fasting for a couple months now combined with daily exercise. So far I’ve dropped 35lbs since I started fasting, gained muscle mass and I feel better than I have in over a decade. I no longer have the unhealthy cravings I used to suffer from, I don’t get nearly as hungry as I used to and it takes much, much less food to fill me up. I also started doing Keto a couple months before that and for some reason I’m finding that between Keto, fasting and exercise this “diet” has been significantly less stressful for me than anything I’ve done in the past.

    I normally fast from 9:30pm until 5:30pm or so the next day (varies slightly based on when I leave work). I’ll eat a very small, extremely low carb nutrient dense meal around 5:30 and another smaller meal around 8:00 with maybe a tiny snack (a couple pieces of salami, a few nuts etc) around 9:00pm.

    I haven’t really been counting calories but I probably should just to make sure I’m getting enough and I’m not unintentionally starving myself.

    I’m 6′ 2″ and a few years ago I weighed nearly 450lbs. I’m down to 323 as of yesterday all with diet and exercise, though sporadic, I’m getting there. Only 100lbs left to lose.

    Maybe it’s because other diets always felt like a constant battle of wills and eventually just wore me down but with Keto and fasting my body seems to actually be reprogramming itself to adapt making this “diet” feel… I don’t know… “smooth”, more natural. I still wouldn’t say it’s necessarily easy, especially that first week but it’s definitely a lot easier than anything else Iv’e done and feels so much better.

    I’ve never felt more motivation and drive than I have with the Keto/IF diet.

    • SarahJ89 says:

      “Maybe it’s because other diets always felt like a constant battle of wills and eventually just wore me down but with Keto and fasting my body seems to actually be reprogramming itself to adapt making this “diet” feel… I don’t know… “smooth”, more natural. ” Yes. I agree, especially on the ongoing battle of wills.
      I also have found I don’t eat larger meals to “make up” for the fast. I’ve learned a regular sized meal is just as satisfying and doesn’t undermine the fast day. My body neither needs nor wants that “extra” food to make up for what I would think of as a deficit. It’s become obvious to me in the past IF four months that I’ve been eating more than I need for a very long time now. I’m learning to trust my body’s ability to take care of itself with the usual amount of food instead of trying to fill the perceived IF “hole” after a fast. There is no hole. My body just takes things up where we left off. Who knew? (Hint: Definitely not me.)

  11. Kevin R. Smith says:

    I wouldn’t put Blue boxes around the titles of each section. It’s way too easy to read right past the title thinking it’s one of those pesky ads. 😉

    • SarahJ89 says:

      God yes. The article was a graphic nightmare! The boxes looked like ads and were very distracting. I almost bailed after the first one or two, glad I stuck it out.
      But whoever thought that was a good idea… nope.

  12. kjawbb says:

    I’ve been doing the time-restricted meal plan since mid June. I was a sit at my desk and snack all day eater, then go home and eat a big meal. I’ve not done any added exercise and have only lost 10-12 pounds but I’m happy with that start!!!

  13. sterlingVT says:

    Diabetics CAN do intermitent fasting

  14. Holly Brown says:

    The 2017 random study was for alternate day fasting not intermittent fasting. It also does not say anything about what they ate. Most of those doing the intermittent fasting may also have cut out all processed sugars, starches and all grains, which would be key to the intermittent fasting weight loss and feeling well. I would be willing to bet that they didn’t alter their food choices, hence the reason for the drop outs because it isn’t sustainable unless you can get your body to switch to fat burning during the fasting window.

    • SarahJ89 says:

      I really can’t eat sugar the day after a fast. If I did I’m sure my body would adjust and the cravings would re-establish themselves. It’s summer where we live and there are people eating sugary things outdoors all the time now. I look at them on the day after a fast and my gut reaction is “ugh.” The fast seems to reset my body somehow.

  15. Ken Montgomery says:

    I did the 19/5 (fast / eat window) and lost about 50 pounds in 4 months. 6 inches off my waist. I also did a lot of cardio. Importantly I didn’t “cheat” at all on the fasting so I let it take full effect. I also have a cup of coffee or two in the morning. There are days I’m not even hungry after 19, 20, 22 hours… i have to remind myself to eat. For me there are two aspects to it… Physically I feel better than I have in a long time. And 2, it feels great to have the mind / body connection thing going. There is something very holistically rewarding about it.

  16. Paul S says:

    I have been intermittent fasting for 5 years. Mostly lean gains feeding window method. All in all I’ve lost a total of 100 pounds, I have more energy than people half my age and look 15 years younger.

  17. Leslie Darwin Harrington says:

    What fasting plan are most people having success with?

    • Tina says:

      16hrs of fasting and 8hrs of eating is the normal method people do.

    • SarahJ89 says:

      I do fast days on Mondays and Fridays, eating only 600 spaced out calories on those days. That works well for me, but I’m a sprinter personality so I can get through short adversities. I feel in charge because *I* decided to do this.

      Someone with a steadier, more marathoner type personality might do better on the daily time-frame fasting. It would grind me down. I have trouble doing *anything* every day, day after day.

      Either approach works. See what works for you.

      • Tina says:

        women are not supposed to eat less then 1000-1200 calories a day, at that point your starving your body. I was told that by my trainer.

  18. Joseph Piñeiro says:

    Lol @ Time restricted eating is where “you fast anywhere from 8–20 hours per day”. 8 hours? I sleep 8 hours a day guess I do it yay for me!

  19. Tina says:

    I did it for 3 weeks, lost 12lbs and 4 inches in my waist, was doing it everyday. It does work, there is tons of stuff out there to back it up too! I had to stop doing it for a bit because I started to get lightheaded 2hrs before meal time. Hope to start it back up soon =)

  20. steve poling says:

    I used the MyFitnessPal food log for daily calorie restriction when I lost 100 pounds, but when I started doing intermittent fasting, it yelled at me on fast days saying I had not consumed enough calories. Thus I quit logging food. Has MyFitnessPal gotten wise to intermittent fasting? I see it now lets me enter feeding times, but last time I had a fast day I logged my electrolyte drink, but it still yelled at me.

    • SarahJ89 says:

      Ignore the yelling. That’s what I do on the days I track my fasting. I don’t do it often, but sometimes I feel it’s a good idea to spot check my fast days on 5-2 just to make sure I’m staying on track.

      They yell. I ignore. My body, their software. The yelling’s at the bottom of the page so it’s easy to ignore. The weight chart report showing my loss over time is in the middle of the page so it’s easy to enjoy.

      This is *your* program. Ignore their tinny, tiny, impotent yells. You’re in charge. And you’re doing a great job, too.

  21. Derelyn says:

    IF has worked really REALLY well for me. I’m 35 (about to be 36) year old female. Two kids. I’m 5’2 and I’m petite. I prefer fasting windows (today is 10-6) but my usual is anywhere between 1-9, 2-10, or 3-11. I have found that I make better food choices on IF (healthy fats – avocados, chicken, whole grains, etc. so I don’t get as hungry during my fasting periods). Everyone is different. My macro distribution is 40% fats, 40% carbs, and 20% protein. Sounds crazy I know, but this just proves that no one thing works for EVERYONE. People would always tell me my protein was too low but this works for me. I have maintained my weight. I play soccer one day a week, and I usually do about 10-15 minutes of yoga per day. I would like to add in more physical activity but my life style is presently hectic. Soccer is my saving grace. I would recommend someone give it a try. If it doesn’t work, then try something else – but stay focused on eating well as much as possible.

    • Tina says:

      You know you have to get the full 16hrs to reach ketosis for it to actually work properly right? You have to keep it consistent or eventually it will backfire, ive seen it happen, ive had trainers to tell me to keep the same time everyday or eventually it stops working

      • Derelyn says:

        Yes, my fasting windows are at least 16 hours. The time frames listed above are my eating windows. I adjust based on what activities I have planned for the day. If I change my window I adjust accordingly. I am not on IF to lose weight.

      • Bart says:

        No, you actually do not. If you eat late a few times, no big deal at all. Trainers are gonna spout stupid stuff some times, just as nutritionists do.

        • Tina says:

          Actually I have tested both ways, there is also proof out there too. 16hrs then eat for 8 then back to fast for 16, it works. I tried to eat before my 16 was up and no results. But everyones bodies are different. Im down 218lbs now… so yeah… proof it works.

  22. SarahJ89 says:

    Intermittent fasting has worked very well for me. I don’t know why writers keep harping on the fact that according to the recent study it’s “only as good as, but not better than” daily calorie restriction.
    There’s much more to weight loss than weight loss. I have done typical WW and MFP programs for 40 years. At one point I lost 70 pounds and kept it off for decades. Eventually though, I regained the weight. Over the years I’ve found I can stick with a “food plan” approach long enough to lose ten pounds. After that I want to rip my hair out at the constant weighing, measuring and obsessing about amounts. Ugh.

    I never considered the 5-2 approach because (du-uh) I didn’t realize you didn’t have to do the two days in a row. My cousin, who lost 4 stone (a stone = 14 pounds) in four months, clued me in.

    I am hypothyroid, plus I’m old. But the day after my 70th birthday I decided to give it a go. Since then I have lost a stone in a pretty steady one-pound-a-week pace. This includes a three-week trip to the US during which I had little control over my food, but didn’t gain an ounce.

    All my life I’ve been out of touch with my body. Fasting has caused me to experience what hunger feels. Now I can recognize it when it occurs on the non-fasting days. Also, it seems to somehow “reset” my body in a way that immediately rids me of any cravings for sugar. I’ve been exploring what it feels like to be hungry and not hungry in a new way.

    Monday and Friday are my fast days. My friends and family are quite used to it by now. On those days I eat about 600 calories–a banana for breakfast and a salad with tuna or two eggs for the other two meals. Yes, around 8:00 pm I’m pretty hungry. I go to bed early on those days, knowing a good breakfast awaits me.

    For me the 5-2 approach really IS better than the more traditional drip-drip-drip, willpower-eroding daily weighing and measuring to achieve the same result. I’ve been doing this for four months now, longer than I usually last, and look forward to more.

    A plan you can stick to over time is better for you. We each have to find our own path. This is mine.

  23. Gumnuts says:

    Eat less, do more. Helped me lose 25kg.

    • Tina says:

      That’s because 80% of the progress comes from the food you eat, 20% just helps it work faster. If you eat right and keep moving instead of sitting around, it helps, they say abs are earned in the kitchen and its true. Til the rest of you gets to a certain body fat % it wont fully pull from your gut. Read that in a Muscle Fitness mag.

      • Gumnuts says:

        Are you fit then?

        • Tina says:

          I was in highschool but I got bullied for it, where I grew up in Canada they frowned upon girls who lifted weights, did sports and track. When I graduated in 2000 I gained 250+lbs, I am now down 215lbs, still got some work left but I am getting so close to the finish line now. My doctor says I do carry more muscle then most and I don’t look the weight I am (235) because of it.

          It does help that I am in wrestling school and I train 6 days a week too at the gym, so its a matter of time getting to that finish line! =)

  24. Kevin Brown says:

    Thank you for posting a truthful evaluation of Intermittent Fasting. There is so much mis-information out there. I have been doing it over a year and am the healthiest I have been since I was a kid. It really does work. I lost 45 pounds in 2 months of Keto and another 20 pounds doing IF. I recommend it to everyone. But you have to be “fat-adapted” first or you will feel horrible as your body needs to transition to using fat as an energy source, and this generally takes 2-4 weeks (thus, Keto is a good start first!).

  25. Freddy says:

    What’s missed in this article is your workout schedule combined with intermittent fasting can creating bigger weight loss than not fasting. If you schedule your daily workout toward the middle or end of your fast your body will burn stored fat instead of food recently consumed.

  26. Vanessa says:

    I did some IF between the months of March and July. I had an InScan done at the end of July and found that I actually lost 2 pounds of muscle. And the only change I’d incorporated was IF. So, contrary to what the proponents say about it, it can make you lose muscle.

    • Tina says:

      If you take HMB supps you wont, and if you continue to lift weights and do a good training routine you wont. I know this cause I do this 🙂 What my trainer told me too!

  27. Theresa says:

    Intermittent fasting IS for Type 2 Diabetics. Read the work or listen to the pod casts of Dr. Jason Fung. He is reversing Type 2 with Intermittent Fasting.

  28. Pauline Pantaleo says:

    The bottom line to all his is- what works for each of you, some way you can sustain and is a lifestyle change. There really is no right or wrong method, provided it is a healthy option for your body. Sometimes delay eating but do better with calorie counting on a consistent basis. I enjoy and love the accountability, food journaling, having a set boundary and numbers. The only time I fast is for blood tests! lol I do feel good afterward and notice my tummy feels better, so it is worth thinking about.

  29. David Queen says:

    I started One Meal A Day (OMAD) in May 2017 and started logging my weight July 18th 2017 at 443 pounds as of Sept 4th 2018 I’m at 282 pounds. It seems to working for me.

  30. Paul Dymond says:

    Just to clarify that the Eat Stop Eat protocol promoted in the book of the same name by Brad Pilon is different from the Alternative Day Fasting method. Eat Stop Eat promotes one to two 24 hours fasts on non-consecutive days, with the meal that breaks the fast being a normal sized meal (as opposed to 5:2 which promotes a small meal of 500 calories or so to break your fast). With Eat Stop Eat on non-fasting days you eat at maintenance level calories, not as much as you want.

  31. HollieTx says:

    Very interesting. This probably explains why I felt so good during the 2 days I had to fast before my colonoscopy.

  32. Bart says:

    As Dr. Fung says, people have been fasting for thousands of years, in practically every culture or religion ever, for the incredible health benefits it provides. I understand the age old need to CYA, but it’s frankly ridiculous that you caution our “safety” doing it.

    If you have type 1 diabetes, cancer, heart problems, sure. Otherwise? We are conditioned to eat all the time because that sells products. Period. Three meals a day are not at all necessary. Snacking between meals is just madness, but if you follow the typical, outdated, CW, that MFP pushes with every article, good luck not snacking constantly. Carbs CAUSE that. There are zero essential carbs, the only carbs you really need are low carb vegetables. Eat twice a day, within an 8-10 hour window. You will not regret it.

    Finally, you talk about autophagy in an article on IF, while recommending against longer term fasting. The problem with that is that autophagy doesn’t kick in very much until the second or third day of longer term fasting.

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