A Beginner’s Guide to Fat

by Trinh Le, MPH, RD
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A Beginner’s Guide to Fat

Are you (still) afraid of fat? Don’t be. For decades, we’ve been advised to steer clear from fat because it was thought to cause weight gain. Luckily, the nutrition world is waking up and realizing that fat plays an important role in every healthy, balanced diet. Learn about the basics of fat, and find out how fat affects your weight goals.

fat basics subhead

A gram-for-gram comparison of fat versus carbs and protein shows: At 9 calories per gram, fat is the most calorie-dense of all the macronutrients. It makes sense, since one of the biggest roles of fat is energy storage (just in case we need it). It’s hard for most of us to appreciate, but fat actually helps our bodies function correctly in several ways:


Fat plays a protective role for cells because it’s an important component of every cell’s membrane or “wall,” which protects against invaders. Fat protects your organs by cushioning them from the impact of everyday living. You also need certain fats to build and maintain a healthy brain, which is about 60% fat in composition!


For day-to-day activities, fat is the main type of fuel our bodies burn for energy. Generally, during activity where your heart rate is less than 70% of its maximal rate, fat serves as your body’s primary source of fuel. Interested in learning more? Check out how to use heart rate training.


Fat aids the release of CCK, a gut hormone that helps you feel more satiated after a meal. Pairing high-fat foods with high-carb foods helps prevent a rapid spike in blood sugar. How? Fat slows down digestion and the rate at which sugars from carbs enter the bloodstream.

For more basic facts on fat, check out Nutrition 101: Fats.

determine fat needs subhead

The Institute of Medicine (IOM) suggests that fat make up 20-35% of total calories in your diet, but you can certainly eat more or less depending on your goals. The MyFitnessPal app automatically allots 30% of calories to fat—of course, you can tailor this to meet your needs.

To determine your fat needs in grams:

  • Step 1: Decide what percentage of your calories you want to come from fat. Choose a 20%, 25%, 30% or 35% fat diet. Convert this number into a decimal (for example, 30% is 0.3).
  • Step 2: Multiply your “Total Calorie Goal” (your calorie goal given by the MyFitnessPal app) by the decimal value. This gives you the number of calories from fat.
  • Step 3: Divide the number of calories from fat by 9 to get the grams of fat.

Does this match your fat goal in the app?

tip 1 fat

understanding fat subhead

Fat is found in a wide variety of foods, either as naturally occurring or as added fat during processing and cooking. Naturally occurring fats tend to be found in dairy (think cheese, yogurt, milk), meat and fish, nuts and seeds, oil and fatty fruits (think avocado, olive). Added fats tend to be found in processed and packaged goods. Of course, not all fats are created equal when it comes to health, so here’s a brief run-down of the common fats found in food:


It’s solid at room temperature and mostly comes from animal sources like meat, particularly red meat, and dairy. Certain plants and their oil are high in saturated fat, such as coconut and palm. Virtually all major health organizations advise us to eat less saturated fat since it raises LDL cholesterol, a risk factor for heart disease. This is why the MyFitnessPal app sets your saturated fat limit at less than 10% of total calories.


Most trans fat found in food are synthetically made by taking liquid unsaturated fat and blasting it with hydrogen so that it resembles solid saturated fat. Why? Because this makes it more shelf stable, easier to cook with, and allows manufacturers to replace saturated fat in their products. Sadly, this backfired, as evidence revealed that trans fat are one of the worst things for your ticker. Not only did trans fat increase LDL (bad) cholesterol, but it also decreased HDL (good) cholesterol. For this transgression, the MyFitnessPal app sets your trans fat goal at 0 grams per day.

tip 2 fat


They’re what we think of when we say “healthy” fats because they don’t carry the same risk for heart disease as saturated and trans fat. Generally, MUFA and PUFA are found in high-fat, plant-based foods (avocado, nuts, seeds, olives) and fatty fish (salmon, tuna, mackerel). The fat in these foods are liquid at room temperature, and we’re advised to eat them in place of saturated fat.


While they’re technically polyunsaturated fats, the omegas deserve a separate call-out since our bodies cannot produce them. Both omega-6 and omega-3 fats play important roles in regulating our immune systems. Omega-3 fat plays an essential role in developing our vision and nervous systems. Adequate intake for adults range from 12-17 grams per day for omega-6 fats and 1.1-1.6 grams per day for omega-3 fats. We easily get enough omega-6 fats from the foods we eat because soybean, safflower and corn oil are abundant in our food supply. Omega-3 fats are harder to come by since they’re mostly found in fatty fish; this is partly why we’re advised to eat more seafood by the 2010 Dietary Guidelines for Americans.

enjoy fats subhead


Meat and dairy can certainly have a role in any balanced diet, but they shouldn’t make up the majority of your intake. Enjoy them in moderation along with plenty of whole grains, veggies and fruits.


Eating fats along with foods that are rich in fat-soluble vitamins and minerals allows your body to better absorb them. A good example: Use high-fat salad dressing to maximize your absorption of the vitamins and minerals from the veggies in your salad.


Most of the fat in our diets supply us with plenty of omega-6 fats, but we should be getting a better balance between omega-6 and omega-3. Both fats play a role in keeping inflammation in check, so it’s important that we get a good ratio of the two.


Different cooking oils provide varying amounts of saturated fat, MUFA and PUFA, plus they impart different flavors and aroma to your food. To get the maximum benefit in a budget-savvy way, purchase olive oil (for low-heat cooking) and canola oil (for high-heat cooking. Olive oil provides valuable MUFA and omega-6 fats, but canola also has a decent amount of omega-3 fats. Learn more by reading cooking oils decoded.



List of healthy fats you can grab quickly at the grocery store.
Food (per serving)CaloriesTotal Fat (g)MUFA (g)PUFA (g)
Almond (1oz)1641494
Cashew (1oz)1571272
Walnut (1oz)18518313
Peanut Butter (2tbsp)1881674
Cheese (1oz)1151020
Yogurt (170g)104310
Dark Chocolate (1oz)1641130
Avocado (1/2 fruit)16014102


Quick list of foods naturally high in omega-3 fatty acids.
Food (per serving)CaloriesTotal Fat (g)Omega-3 Fats (g)
Flaxseed oil (1tbsp)120147.3
Chia seeds (1oz)13895.1
Walnuts (1oz)185182.6
Salmon (4oz)203122
Ground flaxseed (2 tbsp)6093.2
Sardines (4oz)236131.6
Tofu (1/2 cup)7830.6

how body uses fat subhead

Having a certain amount of fat on board is crucial for life—so much so that our bodies have figured out a way to make fat even if we eat almost no fat at all! Excess carbs and protein can both be converted into fat and stored as energy, or used in some of the important functions we mentioned above in Fat Basics.

Not surprisingly, significant fat breakdown occurs when your body runs on a calorie deficit. In a healthy adult, calorie deficits occur mainly by restricting calories consumed or by undergoing a tough workout. When this happens, your body taps into its own fat stores, breaking them down for energy through a process called “beta oxidation.” This process requires glucose, which can come from carbohydrates or protein, and is most efficient when you’re mildly restricting calories. Not only does the body burn fat during calorie deficits, but it also burns fat during normal day-to-day activities. Fat is the primary source of fuel when you engage in low-intensity movements, from sitting in front of the computer to walking the dog. The body does this so it can spare glucose (the good stuff!) for your brain and red blood cells.

fat tip 3

fat myths subhead


Your body stores fat mainly from excess calories. If a calorie excess is available, even if those calories are from carbs or protein, your body is fully capable of turning them into fat for storage.


Your body burns a combination of carbs, fat and protein. At rest and during low-intensity exercise (e.g. exercising at less than 70% maximal heart rate), fat is the fuel of choice. Your body’s fuel of choice shifts to carbs when you exercise harder—at a moderately intense pace and beyond.


Contrary to what the label might tell you, low-fat and nonfat versions of foods tend to contain more fillers and additives to make up for missing flavor. A common additive is, unsurprisingly, sugar (or any one of its 44 cousins).

How do you fit fat into your weight-loss or gain routine? Share your comments below.


  • Ryan

    most of us who join this site are considered ‘advanced’ when it comes to the topic of fat…am i right?

  • james pogrebetsky

    I came on here to post about how this article was all wrong. Turns out, I’m very biased and was expecting yet another hatchet job against fat. What can I say, I jumped the gun, based on the 95% of articles I see that fear fat in all forms. Congrats on actually putting the truth out there!

  • Northwoods Dan

    Pretty solid article. Nice to see fat not demonized. I do wish the “non-link” between saturated fat and mortality was discussed a bit more. Just because saturated fat raises LDL does not mean that we should choose canola, a very modern oil.

    Even so, I think this article was well balanced and a welcome departure from 1980s think.

  • Russ the Muss

    Love your articles Trinh Le I have learnt a lot since I started reading them. I now better understand how my body functions and what you explained is exactly my own experience with my body weight. Don’t know about the lower intensity workout being a better fat burner though as HIIT works well too.

  • Ingrid Rampton

    Hi, my name is Ingrid, I have been overweight before and managed to loose 65 kg back in 2006, I felt really great, my son had beaten brain cancer in 2005 and my reasoning was, if he can beat cancer I can beat my weight issues. And I did. Until his relapse in 2009, and then his passing in 2011, left me devastated, as I am an emotional eater I didn’t care. I thought what’s the point. If I join him all the better. This needless to say is not working for me anymore, nor would Jordan want me to. I’ve just been diagnosed with fatty filtrated liver and gastritis, I need to loose weight and excersize, due to my chronic degenerative disease in my lower back and severe arthritis in my right foot excersize is not an option at the moment. I am 130 kg and wondered if I can loose some weight first then excersize when I’m a little lighter. And due to fatty liver do I need to reduce all fats? Please help me to help myself. I’ve done this to myself but wish to reverse it, if at all possible. Thank you in advance.

    • nikki

      I’m truly sorry for your loss, I just lost my close father in law to the same thing 3 weeks ago.
      One thing is yes you can lose weight at first with diet alone, but its going to take a while… So be prepared for that. Starting with diet (not fad diet, a lifetime diet) is a great place to start to get back into things. Besides, you can’t out exercise a bad diet! However, there are exercises you can do right now even with pain and physical limitations.
      Go on YouTube and look for videos for seated exercise for beginners. You really should do at least some exercise as it will make you feel better quickly and help JumpStart your weight loss! I hope this helps and good luck on your journey!

  • B1ue52

    As others have mentioned, it is refreshing to see an article not demonising fat. Nothing winds me up more than hearing people talk about how fat makes you fat and they choose all the low fat options rammed full of sugar. I enjoyed the article and it’s message. However, I too would also like to see saturated fats talked about a little more in an exercise context. Whilst we know that saturated fats are a precursor to cholesterol, we also know that cholesterol, in turn, is a precursor to testosterone production. So when saturated fat is combined with resistance based exercise, not only to we largely negate the adverse effects of fat = cholesterol, we achieve a natural increase in something we all, men and women alike, need in spades when trying to alter our body compositions. I would like to see this explained more for the masses.
    I personally am currently on a long term cutting cycle after 2 years off training due to injury. My fat intake is 45% of my macro profile and I avoid only trans fats. Whilst running a 600Kcal deficit based on 45% fat, 40% protein and 15% carbs and training hard 4 times per week I am making great fat loss gains and retaining muscle without an issue.
    Fats for me are a godsend – My dietary intake of all foods is very regimented on a weekly basis as I find it easier this way. I bulk make my lunches and dinners for an entire week. I inject my fat content by making sauces, usually dairy based to liven up my heavily protein based recipes. It makes everything so much more tasty and palatable when you are eating the same thing day on day.
    If you exercise hard, then I don’t think the 35% cap advice should be adhered to.
    Great article and breath of fresh air – Hopefully bit by bit articles like this can begin to undo the world of BS the various agencies, manufacturers and governments have created over recent decades. I am a firm believer that the low fat, high fruit recommendations that have been touted in that time are a huge contributory factor in todays obesity epidemic. Please follow up this article with more on the dangers of low fat foods, high sugar content, the sugar alternatives that let manufacturers get away with lying about sugar content and evils of fructose and BS products like Special K!! 🙂

  • Nice to read a beginner’s guide – a lot of people still don’t understand that our body needs fat!

  • Bruce Spencer

    Well, it depends. Plenty of people see a rise of LDL and HDL with a diet high in saturated fat. What most people see is “OMG, MY LDL AND TOTAL CHOLESTEROL IS OFF THE CHARTS!” . what they fail to realize is their Triglycerides have went down and their HDL have went up. So their HDL to Triglyceride ratio has improved. Next they don’t know what the partical breakdown of their LDL is. Eating high amounts of saturated fat typically causes a rise in large fluffy LDL particles which have been shown to not be a problem with clogging arteries like the small dense LDL particles are.

    So it is true for some (maybe even most) humans that eating a lot of saturated fat will raise your LDL, but its not necessarily a bad thing.