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Yoyo effect

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Written by Kenneth Nwosu
| · 18 min read time

The Yo-Yo Effect: Gaining weight again after you have lost weight, causing you to end up at the same weight. What are the causes and consequences of this effect?

Table of Contents

What is the yo-yo effect?

The yo-yo effect is a well known principle: people first lose a lot of weight, but then quickly climb back to their original weight or even higher.

Although the result is familiar, there is still plenty of uncertainty about the cause. In general, however, it is assumed that two important factors play a role:

  • Stopping the temporary effort that led to the weight loss
  • Overcompensation by the body in response to the earlier weight loss

Unfortunately, people often see a diet as a temporary effort. Eating less or healthier for a while to lose weight is fine. But if you then return to your old eating pattern, it is logical that the result of that diet is only temporary as well.

In addition, the increase in weight can now happen even faster. The less food comes in, the more effort your body makes to handle energy economically. Your metabolism slows down and remains slowed for some time when you start eating more again.

Afraid of the yo-yo

I regularly get asked why I have never participated in a bodybuilding competition. After all, I am a fan of the sport and like going to competitions to watch and report on them. Still, I have several reasons not to compete myself. One of them is the principle "If it ain't broke, don't fix it". I am very aware that I am very lucky with my natural body fat percentage. I am afraid of disrupting an apparently favorable metabolism with an objectively extreme diet.

The idea behind this is that I am afraid of giving my body a reason to store more fat. For example, by giving my body the idea that there is a shortage of available food. A recent study in which multiple animal species were observed strengthens this thought. However, I would not dare call it real confirmation.

"Brains interpret dieting as a brief famine"

Researchers from the universities of Exeter and Bristol published their findings in the journal Evolution, Medicine and Public Health[1]. According to their findings, repeated dieting would lead to extra weight because the brain interprets the diet as a brief famine. Especially repeated dieting or yo-yoing would give the body incorrect information about the availability of food.

Our work therefore proposes a potential cause of the association between weight cycling and weight gain: that dieting attempts cause weight gain via providing (misleading) information about the environment to the subconscious systems that control body mass

A.D. Higginson, University of Exeter

Theoretical model of the Yo-Yo Effect

First of all, it is important to mention that the study is based on a theoretical animal model. The researchers developed a formula intended to represent how animals respond to their environment. Here you should mainly think of applying knowledge from evolutionary theory and how animals increase their chances of survival.

In the formula, that environment is represented by 4 variables:

  1. The animal's current energy reserves, especially body fat
  2. The current amount of available food
  3. The current state of the world. Is there often a shortage of food or does this occur often
  4. The current estimate the animal makes of the current state of the world

Based on these variables, the researchers drew up several formulas. Formulas that calculate how much energy is used under which situations and how much energy it costs to store fat. But also to what extent the chance of survival is increased when more fat is stored and under which circumstances.

Their model shows that the animal with the greatest chance of passing on its genes stores extra body fat between periods of food shortage.

Yo-Yo Effect in practice

According to Higginson, their model predicts that the average weight of people who diet regularly is higher than the average weight of people who never diet. This would happen because people who do not diet tell their body that there is a reliable source of food and therefore less reason to store fat.

Our simple model shows that weight gain does not mean that people's physiology is malfunctioning or that they are being overwhelmed by unnaturally sweet tastes.

Professor John McNamara, University of Bristol's School of Mathematics.

For many bloggers who picked up the news worldwide, it was enough to share only the press release and the nicely clear conclusion:

The best thing for weight loss is to take it steady. Our work suggests that eating only slightly less than you should, all the time, and doing physical exercise is much more likely to help you reach a healthy weight than going on low-calorie diets

A.D. Higginson, University of Exeter

"Simple models"

Of course, I wanted to study the research itself critically. What kind of "simple models"? How should I imagine this? What did you test and how solid is the data? Two hours of headaches later, I gave up. To give you an idea:

Let me put it this way: I did not drop advanced math at school as early as possible for nothing.

More practical research into the Yo-Yo effect?

So I quickly gave that up and looked for research that I could understand and assess for value. Earlier today I wrote in response to a Finnish study [2]. That showed recovery in the hormonal system of female fitness athletes in about 4 months when they start eating more again after a competition[2]. However, this was after one competition. What happens if you do this again and again? Not much good, according to a 2006 study, coincidentally from Finland again[3]:

Repeated cycles of weight loss and regain appear to enhance subsequent weight gain and may predispose to obesity. Chronic dieting with weight cycling may be harmful for permanent weight control.

They followed former athletes from sports for which they regularly had to lose weight to compete in a weight class. Think especially of boxers, wrestlers, weightlifters and similar athletes. They came from a cohort of 1838 Finnish athletes who had taken part in competitions between 1920 and 1965. The men were followed into older age with measurement moments in 19985, 1995 and 2001. At that first measurement moment, obesity appeared to occur three times as often as in other former athletes who did not have to yo-yo. Compared with non athletes, the chance was twice as high.

That last point is pretty shocking. A lifetime of fanatically doing sports, including deliberate weight fluctuation, would give you a higher chance of obesity than not doing sports. In 2001, by the way, there was no longer any difference between the "fluctuating athletes" and the non sporting control group. It is some small consolation that things would apparently return to normal after a few decades.

Various studies compared

However, that is only one study. In 2015, researchers compared the results of multiple studies in this area [4]. They selected relevant studies between September 2008 and September 2013. The studies mentioned above were therefore not included. In addition, they had a broader area of focus. They looked not only at the effect on weight over the long term, but also at other matters that can have a negative effect on health, such as cardiovascular health, cancer risk, risk of death and so on.

After applying various selection criteria, they were left with 20 of the 42 studies. These were studies with human subjects that they considered relevant. They also looked at 7 studies with laboratory animals.

Regarding the animal studies that show a negative influence, they point out that this could have been a direct effect of the changed diet the animals received [5,6,7].

More interesting are the studies with humans. Unfortunately, however, the three relevant studies that specifically looked at the effect on weight did not have athletes as their target group, but mainly people with overweight and older adults.

Yo-yo effect studies in humans

Two of those studies showed a negative effect of yo-yoing on weight. For one of those studies, people with overweight at an "obesity fair" were asked about their past and were weighed and measured [8]. In this way, two groups of about 600 people were created. The division was based on whether people had lost 5 kilos or more more than 5 times, followed by a rapid increase back to the original weight. In this way, a rough division was made between yo-yoers and people who did not meet that criterion.

Body fat and waist circumference were then compared between both groups. The group that regularly yo-yoed turned out to have, on average, more fat mass, a higher weight and a larger waist circumference. However, this is not necessarily a causal relationship. Maybe the yo-yo effect was caused by the higher weight and not the other way around.

Lean mass decreases through yo-yoing

Another study showed that during weight regain, the ratio of lean mass to fat mass was negatively affected. However, this concerned older adults between 70 and 80 years old [9]. Not exactly people who started with a fitness diet aimed at recovery and a training schedule.

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The outcome was comparable in a third study with people with overweight who were followed for another 6 months after losing weight [10]. After 6 months they were not entirely back at their original weight, so not even one complete "yo-yo". Lean mass had decreased and resting metabolism had dropped.

What is the right definition of the yo-yo effect?

It is actually an impossible question to answer: "What are the effects of yo-yoing?"

First, what is the yo-yo effect? Completely different target groups are used in the various studies. How much do you have to lose and regain to fall under this? How often?

Perhaps even more important is the difference between a conscious weight cycle, such as that of a fitness athlete who gets leaner for a competition, and the yo-yoing of someone with overweight who cannot maintain the result of his or her diet.

The studies that look at different situations, a partial, complete or multiple cycles, still do not seem able to provide a clear answer.

Yo-yo effect and risk of heart disease in women

Women who regularly lose weight and then regain the same weight, the 'yo-yo effect', have a higher chance of heart disease.

At least, that is the preliminary conclusion of a study that was recently presented. This happened during the Epidemiology and Prevention | Lifestyle and Cardiometabolic Health Scientific Sessions of the American Heart Association's. This year is the first edition of this global exchange of the latest developments in cardiology.

Brooke Aggarwal, senior author of the study, reported the preliminary findings during the meeting. She and colleagues studied 485 women, average age 37, with an average BMI of 26. At the lower end of the 'overweight' category. The women recorded how often they had lost more than 10 pounds, 4.54 kg, and regained that same weight within a year. Pregnancies were not counted by the researchers.

Life's Simple 7

To determine cardiovascular health, the women were assessed using the American Heart Association's 'Life's Simple 7':

  1. BMI
  2. Cholesterol
  3. Blood pressure
  4. Blood sugar
  5. Smoking
  6. Physical activity
  7. Diet

Results

Almost three quarters of the women had experienced the yo-yo effect at least once. The number of times they fluctuated in weight this way varied from 0 to 20 times. The researchers saw that women for whom this happened once or more had a lower chance of an optimal BMI. This chance was 82 percent lower, while the chance of an optimal score according to the 'Life's Simple 7' was 65 percent lower.

The more often the women had experienced the yo-yo effect, the lower the scores on the Life's Simple 7. It was striking that this effect was strongest for women who had never been pregnant.

The women without a pregnancy history were likely younger and might be those who started weight-cycling at an earlier age. We need to identify critical periods for the effect of weight fluctuation on heart disease risk over the life course to find out whether it is worse when women start on a dieting roller-coaster at an early age

Follow-up research into the yo-yo effect

The researchers want to extend the study by 5 to 10 years to confirm the current results and look at the long term effects.

A limitation of the study is that no distinction was made between intentional weight loss and unintentional weight loss. In addition, the study is based on self reported data from the participants and measurements performed only once.

It also cannot be assumed that there is a causal relationship. The yo-yo effect could possibly also be a result of a lower score on the mentioned 7 point scale instead of the other way around.

Finally, the current study says nothing about a link between the yo-yo effect and the risk of heart disease in men. Earlier research, however, has shown similar results in men. Men who often fluctuated in weight turned out to have twice as high a chance of dying in middle age from cardiovascular disease.

Yo-Yo Effect cause

Our body is masterful at maintaining the status quo. Preferably, your body keeps everything the same. Major changes are often considered undesirable, as a possible reaction to a hostile environment. The body then creates a counterreaction to find balance again.

A strict diet can be an example of such a 'hostile environment'. The body recognizes the shortage of food and, as it were, puts itself into energy saving mode. The energy that comes in is stored faster and burned less quickly. A very efficient way to postpone starvation for as long as possible. After all, your body has no idea that you are deliberately starving yourself. Consequence: the same shortage of food leads to less and less weight loss. So you have to eat even less, after which your body responds again by lowering energy expenditure further.

It would be useful if we could tell our body that there is no scarcity. That there is enough food available, but that we are deliberately creating a shortage. That we are trying to make up for the result of a previous surplus.

"Yo-yo effect caused by the brain"

Losing weight would then become a lot easier, since your body would not be actively working against you. But possibly more important: the chance that you regain all the lost weight in a short time would also become a lot smaller.

Now, after a diet, people often find out what happens when your body is still in energy saving mode while 'the scarcity is over'. When you decide to eat a bit more again while energy expenditure is still reduced. The kilos come back on, often much faster than you lost them. Fine if you wanted to take some nice photos once or had to lose a few kilos for an acting job. In most cases, however, we never want to see those lost kilos again.

Preventing the yo-yo effect

There is hope on the horizon. Researchers at Monash University have found a molecular switch in the brain that regulates the burning of fats. They suspect that this 'switch' drives the extra storage of fats during long periods of energy shortage. Being able to control this switch should make weight loss easier. This would make metabolic diseases such as diabetes easier to treat and/or prevent.

The researchers from the Monash Biomedicine Discovery Institute identified a protein in mice called carnitine acetyltransferase. This was found in the brain cells that regulate fat storage in times of hunger. In mice in which this protein is disabled, fat reserves are used more quickly, both during fasting and afterward when eating resumes. The findings were published in Cell Reports [1].

This would show for the first time exactly where the instruction is given to store more fat to compensate for lost weight.

Manipulating this protein offers the opportunity to trick the brain and not replace the lost weight through increased appetite and storage of fat. By regulating this protein we can ensure that diet-induced weight loss stays off rather than sneaking back on.

Shane Andrews, Monash Biomedicine Discovery Institute

Stopping the yo-yo effect in the future

Science is discovering more and more about the exact processes that determine how our body handles energy. Last year we wrote about the discovery of another "button". Researchers had discovered a group of neurons in the brain that stimulate binge eating.

Of course, it will take years before such discoveries can lead to actual medication and treatment methods in practice. We regularly write about these kinds of discoveries, where you can always wonder whether and when this can really make your life easier. However, the possible implications of these kinds of discoveries are worth the patience. Let us hope that from now on you will only hear 'yo-yo' when people are talking about toys or rappers.

Conclusion: Only if necessary

In any case, there do not seem to be any studies showing a favorable effect of yo-yoing.

When it comes to losing excess weight, my advice is therefore to prevent yo-yoing, which is of course easier said than done. Less drastic reductions in food intake can help with this. It is better to move toward a target weight in smaller steps and then learn what is needed for maintenance than to lose weight as fast as possible. Fast crash diets prove difficult to maintain. You then have to eat much less than you are used to, your body responds by slowing your metabolism and mentally the idea takes hold that dieting is hell.

For athletes?

For competitive athletes, that is different. They have no choice but to fluctuate in weight and body fat percentage, simply because stage shape should not be maintained for too long. Many fluctuate between a normal weight and a much lower weight with an abnormally low body fat percentage. This is for aesthetic reasons and not health reasons.

To return to my personal motivation, you can therefore ask why you would consciously want to fluctuate in weight if the direct goal is more harmful to health than beneficial. It is easy for me to talk, however. I am always lean without dieting. That natural state is not available to everyone. For many people who would still like to see a washboard stomach once, this means a diet that may not be desirable in the long term. The yo-yo effect is then unavoidable, although of course there is still a difference between a washboard stomach that is just visible and stage shape.

References

  1. A. D. Higginson and J. M. McNamara. An adaptive response to uncertainty can lead to weight gain during dieting attempts. Evolution, Medicine and Public Health, December 2016 DOI
  2. fitsociety.nl/bodybuilding/hormonale-huishouding-vrouwen-goed-herstellen-wedstrijd/
  3. Saarni, S. E., Rissanen, A., Sarna, S., Koskenvuo, M., and Kaprio, J. (2006). Weight cycling of athletes and subsequent weight gain in middleage. Int. J. Obes. (Lond). 30, 1639–1644. doi: 10.1038/sj.ijo.0803325
  4. Mehta, T., Smith, D. L. Jr., Muhammad, J., and Casazza, K. (2014). Impact of weight cycling on risk of morbidity and mortality. Obes. Rev. 15, 870–881. doi: 10.1111/obr.12222
  5. Bogden JD, Kemp FW, Huang AE, et al. Bone mineral density and content during weight cycling in female rats: effects of dietary amylase-resistant starch. Nutr Metab (Lond) 2008;5:34. [PMC free article] [PubMed]
  6. Anderson EK, Gutierrez DA, Kennedy A, Hasty AH. Weight cycling increases T-cell accumulation in adipose tissue and impairs systemic glucose tolerance. Diabetes. 2013;62:3180–8. [PMC free article] [PubMed]
  7. Barbosa-da-Silva S, Fraulob-Aquino JC, Lopes JR, Mandarim-de-Lacerda CA, Aguila MB. Weight cycling enhances adipose tissue inflammatory responses in male mice. PLoS One. 2012;7:e39837. [PMC free article] [PubMed
  8. Cereda E, Malavazos AE, Caccialanza R, Rondanelli M, Fatati G, Barichella M. Weight cycling is associated with body weight excess and abdominal fat accumulation: a cross-sectional study. Clin Nutr. 2011;30:718–23
  9. Lee JS, Visser M, Tylavsky FA, Kritchevsky SB, Schwartz AV, Sahyoun N, Harris TB, Newman AB, Health ABC Study.Weight loss and regain and effects on body composition: the Health, Aging, and Body Composition Study. J Gerontol A Biol Sci Med Sci. 2010 Jan; 65(1):78-83
  10. Bosy-Westphal A, Schautz B, Lagerpusch M, Pourhassan M, Braun W, Goele K, Heller M, Glüer CC, Müller MJEffect of weight loss and regain on adipose tissue distribution, composition of lean mass and resting energy expenditure in young overweight and obese adults. Int J Obes (Lond). 2013 Oct; 37(10):1371-7.
  11. Alex Reichenbach, Romana Stark, Mathieu Mequinion, Raphael R.G. Denis, Jeferson F. Goularte, Rachel E. Clarke, Sarah H. Lockie, Moyra B. Lemus, Greg M. Kowalski, Clinton R. Bruce, Cheng Huang, Ralf B. Schittenhelm, Randall L. Mynatt, Brian J. Oldfield, Matthew J. Watt, Serge Luquet, Zane B. Andrews. AgRP Neurons Require Carnitine Acetyltransferase to Regulate Metabolic Flexibility and Peripheral Nutrient Partitioning. Cell Reports, 2018; 22 (7): 1745 DOI: 10.1016/j.celrep.2018.01.067

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