8 Sneaky Offenders that Cause Weight Fluctuations

by Julia Malacoff
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8 Sneaky Offenders that Cause Weight Fluctuations

When you’re working toward a weight-loss goal, it’s normal to be watching the number on the scale like a hawk waiting for any changes that might occur. But if you’ve been tracking your weight for even a few weeks, you’ve probably noticed fluctuations are common. Still, they can be frustrating to see when you’re working hard to get into your best shape ever.

Even for those who aren’t actively trying to lose weight, it can be unwelcome to see the scale jump up. Rest assured, weight changes from one day to the next are generally temporary and, according to experts, they don’t mean you’re not making progress.

Here, find eight explanations for why your weight can spike — straight from nutritionists who help people meet their weight-loss goals every day — that have nothing to do with gaining fat.


It’s true that staying well-hydrated is a good move if you’re trying to lose weight, but the first few days of upping your water intake could actually cause the number on the scale to creep up, too. Why? “Let’s break down what weight really is,” says Megan Ware, RDN. “It is not just the measurement of fat in the body. It is the weight of your bones, organs, muscles, fluid and waste. When you’re dehydrated, you actually weigh less, but that doesn’t mean you are healthier. Let’s say you don’t drink much fluid one day, and the next morning you wake up and your weight is down. Then you drink a ton of water and the next day it looks like you gained 2 pounds. That does not mean you gained 2 pounds of fat; it just means that your body was depleted of water the day before.”


Lifting weights can speed your progress in the long run, but it can also temporarily cause your weight to appear higher. “I’ve had so many clients tell me they had a ‘perfect’ day: They ate healthy, nutritious foods all day, packed their lunch, made dinner at home and had a really killer workout with their trainer,” Ware says. “They get up in the morning expecting the scale to tell them what a good day they had yesterday, to give them their ‘reward’ for a day well done.” When they see the scale go up instead of down, they understandably get bummed out. But here’s the thing: “Intense exercise causes inflammation,” Ware explains. “In this case, inflammation is actually a good thing. When you are in the gym lifting weights, you are creating tiny little tears in your muscle fibers. When those fibers build back up (with proper nutrition), that’s what causes a change in body shape, tone and additional muscle. Your body takes on more water to help with muscle repair, which can translate to a higher number on the scale.”


It’s no secret that certain types of foods can affect your weight, and sodium is one that can have an immediate (although temporary) impact. “Packaged foods often have high amounts of sodium or salt, which causes you to retain water in your gut,” explains Gillean Barkyoumb, MS, RD, the founder of Millennial Nutrition. “This results in a bloated belly and a higher number on the scale. The good news is that it usually goes away within a day or two.” To avoid this, Barkyoumb recommends focusing on whole foods and using herbs and spices to season your meals instead of salt.


Though carbohydrates are not the enemy of weight loss, eating an unusual amount of them over the course of one day or even a few days can make it seem like you’ve gained weight. “Carbohydrates are another type of food that can result in water weight showing up on the scale,” explains Alexia Lewis, a certified health coach and registered dietitian. “This is why people lose weight faster initially on a lower-carbohydrate diet. The body doesn’t hold onto the extra water. It’s also why people gain weight quickly when they eventually go off that lower-carbohydrate diet; that water weight comes back and the scale bounces up!”


No need to get into the nitty gritty here, but if you’re constipated, you’ll see that reflected on the scale. “If you aren’t going to the bathroom regularly and getting rid of waste, that is going to cause your weight to fluctuate,” Ware says.


Most women know their weight can be affected by their menstrual cycle, but some are surprised just how much weight they can temporarily gain because of their hormones. “About five days prior to your period, you may experience weight gain due to water retention,” Barkyoumb says. “The average woman will gain about five pounds in water weight during this time. No need to panic though; you’ll drop down to your normal weight when you start your period.”


Yup, really. “One small study in first-shift Monday to Friday workers found that people’s weights tended to go down during the workweek, hitting their lowest point on Friday morning,” Lewis says. “Weights went up over the weekends to their highest point on Monday mornings.” People who lost weight overall still followed this pattern, they just lost more weight during the week than those who remained the same or gained weight over the course of the study. “While this is one small study and it cannot be applied to the population at large, it does allow some insight into normal weight patterns,” she says. “Understand that even though the scale is going up and down, over time, overall weight can change.”


Sometimes yesterday’s weight can affect today’s weight for reasons that are all in your head. “Some people cannot get on the scale without judging themselves for the number they see,” Lewis explains. “If the number is up, they decide they have failed, feel bad and resolve to eat less and work out more. If the number is down, they decide they are a success, feel great, and decide they can eat more and work out less.” Ideally, you’d behave the same each day when dieting and over time, your weight would start to trend downward, despite the normal fluctuations, but for many people, this is easier said than done.

“If the scale makes you think this way, consider weighing yourself less often so you don’t see the natural ups and downs,” she suggests. It may also be worth considering adding some alternative methods of tracking to your routine, like weekly measurements and progress photos. That way, your weight is just one of the many ways you keep track of how you’re doing, and suddenly, the inevitable peaks and valleys don’t seem like such a big deal.


  • Jake Wilson

    If you’re strength training correctly, your weight SHOULD go up – otherwise, you’re not doing it right.

  • Klo Light

    Informative article. Thanks..

  • David Hicks

    I find this interesting. I always gain weight over the weekend (1-3 pounds usually) because I tend to eat out, and have more down time when I snack. But, that weight is usually gone by Tuesday or Wednesday and if I am trying to lose weight, I often have a net loss for the week.

    • shawnsBrain

      Yes, this is exactly me too.

    • Brian O’Neil

      Here is the underlying fact that the article fails to address: There are 3500 Calories in a pound of fat. If you’re running a 500 Cal/day deficit for weight loss, most bathroom scales can’t even detect the 1/7th of a pound of fat you’ll lose every day. Even at 1000 cal/day, your meaningful weight loss can’t be seen day-to-day as even a glass of water is more weight than you’ll lose in fat. It also means you almost certainly don’t actually gain 3 lbs over the weekend, because to do that, you’d have to consume an additional 10,500 Calories above what it would take to maintain weight. You don’t do that by eating out and snacking a little bit. That’s eating an entire week’s worth of Calories in two days. This article does kind of explain what’s going on, but missed the more important point that you should not even be thinking about your day-to-day weight loss. If you think you’re going to get rewarded for a “good day” by seeing a lower number on the scale the following day, you’ll quickly grow frustrated and fool yourself into thinking that your good habits aren’t paying off. You shouldn’t have “good days” and “bad days”, you should be consistent every day. Record your weight every day, but only look at results week-over-week.

      • Rick Smith

        Great point and further explanation!

      • Carrie

        10,500 calories is a week’s worth? Maybe if you’re starving yourself. I don’t count calories (because they’re BS), but estimate I’m around 18,000 per week. My weight is stable and appropriate for my height (23.5 BMI).

        • Brian O’Neil

          For what *should* be a typical 2000 Cal/day diet, 10,000 is 5 days, but that’s what you’d have to eat over and above, so if you add in 4000 Calories that would just maintain your weight, you gt 14,500 Calories for the weekend, which is about what a healthy adult should consume in a week.

          • Mark Baloun

            Absolutely patently FALSE!! It is not “simple physics” if you run a calorie deficit you’ll lose weight. It’s 2017 can these silly myths go away please?? They’re so off base it isn’t funny. Tell someone with a thyroid deficiency that all they have to do is run a calorie deficit. Tell a hard gainer in the gym that all they have to do is run a calorie surplus. It is patently false. It’s not black and white. Metabolism is a huge factor some people store everything as fat some people burn everything.. some people use the calories efficiently some do not. I’m a bodybuilder and have been for twenty years.. formerly a competitive bobdybuilder and there are just some silly myths that just drive us nuts. Just run a calorie deficit and you’ll lose weight is one of the most pervasive and painfully false myths around.

          • Brian O’Neil

            Yes, Metabolism is a HUGE factor. Most of a normal person’s daily Calorie burn is base metabolism. This is part of a body’s total energy balance though. If a thyroid condition keeps your base metabolic rate low, it may be difficult or impossible to eat little enough to lose weight while still getting adequate nutrition. However, it is still the case that if you consume less energy than you metabolize, you’ll lose weight. All systems in the universe obey conservation of mass, momentum, and energy, including the human body. And for a normal, reasonably healthy adult, these physics can be used to keep weight under control while also maintaining overall health. To call this “Absolutely, Patently false” implies that the human body is exempt from the laws of physics, and also makes people vulnerable to all kinds of fads and magic pills that profit substantially off of pretending that there is some magical way to lose weight without dieting and/or exercise.

          • robinbishop34

            If you aren’t in a deficit, you aren’t going to lose fat. Someone who claims they aren’t losing while in a deficit are simply not in a deficit.

            I’m not saying there aren’t physiological factors that can/do impact metabolism somewhat, but for a majority of people who frequent this site (very overweight), all they need to do is figure TDEE and eat below that level to drop.

          • SuperBoppy

            I agree. Genetics play a huge role in what a person’s weight will be regardless of what they eat or don’t eat. Around 20 years ago or so, I went on a calorie deficit program and lost 60 pounds. It was one of the most difficult things I have ever done, to constantly measure everything, hunger pangs (not always, but often enough). I lost weight alright, but I lost a lot of muscle as well. Trying to keep the weight off was impossible, even though I was still monitoring my eating. Within a year, I gained all the weight back and then some. A few years ago, I determined never to do that to myself again. I still watch what I eat, but I do not restrict my diet, other than to watch carbs, especially refined ones. I have lost weight and my weight is quite stable. I am still much heavier than I would like to be, but never again will I go on that rollercoaster ride, and restricting calories to the point of making myself ill (literally). My wife is a foot shorter and over 130 pounds less than me, and I eat about the same amount as she does. If you looked at my brother and my mother’s side of the family, the majority have weight issues. Yet I have friends who eat like horses, eat all kinds of junk food as well and are skinny. Genetics and biology is so much more complicated than the “just eat less” crowd will admit.

      • Fischer Bacher


    • Elliott D. Kraus

      Hi, I have stage 4 CKD. Kidney disease.
      I drink 42 oz water daily.
      I drives me crazy when I gain 2 lbs 3 hours later I’m 2 lbs less.

      • Cynthiac LunaRising

        I’m no specialist regarding kidney disease by any means. I am Yoga Instructor, Health/Fitness trainer ~ by trade and life choice 30+ years. How much daily h2o intake do your Drs recommend? My impression is that it is widely held belief & practice to drink a minimum of 1 gallon (128oz) h2o daily just to give your body what it needs to maintain proper level of hydration, even if you are not sweating.

      • James A Tillman

        Elliot, you may want to consider reading the Plant Paradox Program by Dr. Stephen Gundry. By significantly altering your diet you may correct this condition. You can purchase the book on Amazon for about $16.00. By following this program and switching out foods I was able to correct my kidney condition.

        • Katrina Samuel Garrison

          You were able to cure stage 4 kidney disease by eating plants???

          • James A Tillman

            I will not get into particulars or try to explain it because I am not a medical doctor. What I will say is the book is written by one of the top Medical Doctors in the world. If Eliot is willing to read 285 pages he will learn how and why this program works and that the body already has the ability to cure itself. The solution is balancing his gut microbes, drastically reducing the poisons that are getting into his body curing his leaky gut which will eliminate the toxic substances that are invading his system. His body will literally regenerate itself. Cells in most of the body are replaced every 90 days if they get the right fuel along with eliminating the poisons that are bombarding his system and hindering there growth.

  • Glenn Nelson

    I weigh in everyday first thing in the morning and I keep a daily track of my weight. I too have noticed that my weight can be +/- 2% and I realize that this is normal. I also noticed my weigh goes down during the week and then goes up on the weekend. While I try to maintain consistent eating habits and am a monotonous eater during the week, my diet changes somewhat on the weekends (restaurant, friend’s) so I to not freak out as long as I can maintain that */-2%.

    • James A Tillman

      Glenn, I do the same thing. By weighing every day and recording it on a free online calorie/weight counter I see trends which helps tells me if I am gaining unwanted weight and thus can adjust my diet. Every person is different but like you I find keeping track really helps.

  • cherylridgeway

    Funny that I should get this today! I got on the scale today after weeks of not and was not happy so, I decided that today I start doing what I’m suppose to do.

  • Carrie

    “Though carbohydrates are not the enemy of weight loss” is probably the most misleading information here. They are a frontrunner in the list of weight loss enemies, and should be minimized in a healthy diet.

    Weight loss (and weight gain) is always going to have fluctuations. Our bodies are not machines and we do not perform the same activities or eat the same things each day. Look for the longer term changes.

    • MH

      It’s not misleading it factual. Carbs are good, you should be eating carbs, just the right amount. If you deprive yourself of carbs, your body has nothing the burn off when you train so it will got to you next dense source which is muscle. That is how people get skinny fat. YOU should never deprive yourself of carbs, they are you friend. Unless you like being slow and tired all day? Think of carbs as fuel, that is fuel to keep your body moving.

      • Trisha Blann

        You must correct yourself when you speak about carbs. HEALTHY carbs, such as fresh fruits and vegetables, are good for you. UNHEALTHY carbs, such as potato chips, cookies, ice cream and the likes, are NOT good for you, can and will cause weight gain as well as other problems when eaten in excess or as the only carbs a person eats. IF a person chooses to eat these carbs, MODERATION and PORTION CONTROL is AN ABSOLUTE MUST in order to remain healthy and allow room in a healthy diet for healthy carbs, healthy fat, and protein. It’s called a balanced diet for a reason.

        • robinbishop34

          True, but high glycemic carbs are important post (strenuous) workout. They quickly nourish a beaten central nervous system and muscles, while stemming the production of cortisol.

          Its not uncommon for weight lifters, and those who engage in high intensity cardio to have ice cream, or sugary cereal post workout.

          • Trisha Blann

            Also true, but for someone trying to lose weight, not as a weightlifter or high intensity cardio, there needs to be regulation of those type of carbs. Someone who is does not have that type of exercise on a regular basis can not and should not eat high glycemic carbs, but should focus on the low glycemic carbs. There needs to be a differentiation made because there are a lot of people who don’t understand the difference between carbs, or even what portion control is.

          • robinbishop34

            Fair enough.

  • Mark Baloun

    Stop looking at the scale folks.. doesn’t tell you anything productive day to day. I recommend you step on a scale once a month. Day to day? The mirror or bodyfat measurements are where the truth is.

  • Fischer Bacher

    Yes, carbohydrates are not the enemy of weight loss.