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Why Post-Diet Weight Regain Happens & How To Avoid It

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Dieting is hard. Keeping the weight off after you stop dieting is even more difficult. In fact, some research suggests that almost 90% of people who lose weight actually gain it back and then some extra too.

This unfortunate truth is one that many experience when dieting, leaving them in a worse position than before they even decided to diet. For this reason, I decided to address the issue.

So in this article, I’ll be discussing why most people regain the weight they’ve lost and then give some tips to help you avoid post-diet weight regain yourself.

How The Body Adapts To Dieting

When it comes to losing body weight, almost everyone who is actually successful to some extent will regain the weight that they lost, and then probably some more besides. Unfortunately, this phenomenon actually has its own term known as body fat overshooting.

Typically, the scenario goes like this: the individual loses a couple of pounds and then falls off the wagon. Fast forward a month or two and the individual has regained all of the weight they lost, and then also ends up gaining a few extra pounds, leaving them in a worse position than when they started.

In fact, some studies estimate almost 90% of individuals who diet, return to their previous weight range. That’s quite incredible and initiates the need to combat this issue.

The primary reason for this occurring is down to the phenomenon termed “adaptive thermogenesis”, which essentially describes how the body adapts to a reduced calorie intake (1).

When you first begin dieting, you must consider that the amount of calories you’re consuming is allowing your body to maintain a certain weight. Upon reducing those calories from your diet, the body essentially makes up for the missing calories by using your body tissues for energy. As a result, you begin to lose weight.

Eventually however, your body adapts to this lower calorie intake by reducing the amount of calories your body uses for any given activity or bodily function. In essence, the body becomes more efficient so that you don’t continue to waste away. Despite this being a survival mechanism, it’s not great for weight loss or keeping it off (1).

Adaptive Thermogenesis And Weight Regain

As mentioned previously, one of the main issues with weight loss is adaptive thermogenesis, where energy expenditure decreases as a result of reduced body weight and, of course, reduced calorie intake.

Most people in this situation simply don’t understand that the body begins to change in ways that go much deeper than simply dropping a few pounds. As a result, after success with their diet, many people immediately begin eating more calories, which results in this post-diet weight regain (2, 3, 4).

The problem is that as a result of adaptive thermogenesis, the amount of calories that you burn is reduced. Thus, when the diet ends and you immediately begin eating larger amounts of food again, the body simply can’t keep up as your metabolism has reduced.

Let’s say that, over the course of months dieting, your body has adapted to accommodate a daily 1400-calorie intake. If, after you decide the diet is over, you increase calories back up to 2400-calories immediately, what happens?

Well, in this situation, the body simply doesn’t know what to do with the extra calorie intake and shuttles these nutrients to be stored in the body. Certainly one day of excess calorie intake won’t cause major weight gain, but if calories are increased drastically after dieting, over the course of a month then serious weight gain may occur.

While increased calorie intake is a necessity post dieting, the increase needs to be controlled in a way that will reduce excessive weight regain.

Steps To Take During The Diet

Before getting into how to deal with the post-diet period, we first need to ensure that the appropriate steps are taken during the diet to avoid immense desire to stop dieting. This unfortunately, is one of the biggest reasons people gain weight back: their diet simply isn’t sustainable.

One of the most important points I make to clients is to ensure that your diet is sustainable. For most people dieting, they’re looking to make a lifestyle change. In this case, you need to make sure that the steps you took to lose the weight are things that you’ll be able to do when you aren’t restricting calories.

Things like immense calorie restriction, restricting foods you love and never giving yourself a break from dieting, are the three most obvious issues I see on a regular basis.

In the first scenario, many people restrict calories far too drastically in the hope of losing weight. After a few months or even sooner, most realize that they’re miserable, hungry and feel terrible leading to bingeing once the diet ends.

Additionally, many people mistakenly restrict their favorite foods entirely because “they aren’t healthy.” So what happens when you want to indulge? Do you go off the deep end, absconding from the diet entirely? Do you guilt yourself for slipping all the time?

I suggest rather than eliminating foods you enjoy entirely, opt for either reducing consumption slightly or opting for lower calorie versions. Either is more sustainable than saying you’ll never drink pop again, even though you’ve been drinking it for the past 10 years.

Lastly, it’s okay and even suggested to occasionally take breaks from dieting. Doing so gives both your mind and metabolism a break from restriction, which can really go a long way. Further, it will ensure that once you’re done dieting, you won’t binge.

Reverse Dieting

Reverse dieting is a concept which has come into the public eye only relatively recently, but is easily one of the best methods to avoid post-diet weight regain. Essentially, you’re attempting to sequentially increase calories in a controlled manner to avoid excessive weight regain.

To use a reverse diet, you’ll need to have a clearly defined end point to the diet. Simply deciding to abandon the diet is a surefire way to accidentally regain weight. Once you’ve decided on an end point, you can plan how you’ll steadily increase calories.

Once you begin your reverse diet, I suggest increasing calories by around 20% from your current intake. For example, if you were consuming 1400 calories at the end of the diet, you’d want to increase to around 1700 calories for the first week.

Keep in mind that it is best to weigh yourself daily when using this method. By weighing yourself every morning, you’ll be able to first control your weight gain. Regular weighing will enable you to notice any weight fluctuations on a daily basis and adjust intake accordingly.

Second, by weighing yourself daily, you’ll see how your body responds to the amount of extra calories; from there you can adjust future increases of calories based on this weight fluctuation.

After a week or so, evaluate how your weight has changed with the new calorie amount. If weight has remained the same, consider increasing by an additional 20%. If you’ve gained a small amount of weight, you can either stick with the 20% increase or reduce by a small amount.

If you’ve gained a substantial amount of weight, there’s a good chance you ate much more than 20% additional calories. In this case, you should reevaluate just how many calories you’re consuming.

While you may not increase calories by an additional 100%, I suggest continuing this process until you reach around a 50-60% increase of calories and then reevaluate. Just remember, the higher you can get your calories without excessive weight regain, the easier future weight loss attempts will be.

dieting success

Why Post-Diet Weight Regain Happens & How To Avoid It

Dieting can be difficult but keeping the weight off can be even harder. Unfortunately, many people don’t understand why this can happen to them.

With this information and these tips for avoiding weight regain, you should find yourself prepared for issues that plague the post-diet period and understand the appropriate steps to take to avoid this happening in the first place.


  1. Rosenbaum, M., & Leibel, R. L. (2010). Adaptive thermogenesis in humans. International Journal of Obesity, 34, S47-S55.
  2. Dulloo, A. G., Jacquet, J., & Girardier, L. (1997). Poststarvation hyperphagia and body fat overshooting in humans: a role for feedback signals from lean and fat tissues. The American journal of clinical nutrition, 65(3), 717-723.
  3. Swinburn, B., & Egger, G. (2004). The runaway weight gain train: too many accelerators, not enough brakes. BMJ: British Medical Journal, 329(7468), 736.
  4. Dulloo, A. G., Jacquet, J., Montani, J. P., & Schutz, Y. (2015). How dieting makes the lean fatter: from a perspective of body composition autoregulation through adipostats and proteinstats awaiting discovery. Obesity reviews, 16(S1), 25-35.


About the author

Rudy Mawer, MSc, CISSN

Rudy has a 1st class BSc in Exercise, Nutrition & Health and a Masters in Exercise & Nutrition Science from the University of Tampa. Rudy currently works as a Human Performance Researcher, Sports Nutritionist and Physique Coach. Over 7 years he has helped over 500 people around the world achieve long last physique transformations.

He now works closely with a variety of professional athletes and teams, including the NBA, USA Athletics, World Triathlon Gold Medalists, Hollywood Celebrities and IFBB Pro Bodybuilders. If you would like to get in contact or work with Rudy please contact him on social media.

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