What Yo-Yo Dieting Actually Does to Your Body (myth debunked)

Let me start by being completely transparent. When I started digging through the research on yo-yo dieting, I was quite surprised by my findings. I quickly learned many of my assumptions were actually just presumptions not supported (or disproven) by evidence. What does yo-yo dieting do to your body? How bad is it for you? What can we learn from yo-yo diets? Can you get off the weight-cycling rollercoaster? And if so, how?

If you’ve ever been on the weight-cycling rollercoaster, you’re going to want to read this. It’s a game-changer!

What is Yo-Yo Dieting?

I think most people are familiar with “yo-yo dieting,” aka weight cycling. It simply refers to a repeated pattern of recurring weight loss and weight regain. In other words, it’s a term used to describe the sways in body weight from intentional weight-loss attempts (usually involving a calorie-restricted diet) to unintentional weight regain.

In simple terms, yo-yo dieting and weight cycling are terms used to describe repeated attempts at weight loss.

Symbolically speaking, yo-yo dieting highlights the tremendous difficulty in maintaining weight loss for extended periods of time experienced by the overwhelming majority of folks. For example, it’s been reported that 80% of individuals who intentionally lose ≥10% of their body weight will regain that weight within one year. ¹

[Note: this statistic doesn’t account for folks who start a diet but fall off the wagon before they make such significant progress. After all, even though there’s no standard definition, weight cycling implies you successfully lost some weight in the first place.]

Obviously, yo-yo dieting is fairly common. Studies have estimated that some 20 – 55% of men and women have been on the weight-cycling rollercoaster. ²How about you? Have you been on the weight-cycling rollercoaster yourself?

Considering its prevalence, it’s hard to ignore the many “dangers” of yo-yo dieting according to much of the media. But what’s the truth about weight cycling? Does it really adversely affect health outcomes, increase the risk of various scary diseases, and even increase the chances of early death? Or, are the commonly held beliefs about weight cycling misguided or overstated?

Simply put, what does yo-yo dieting do to your body?

Some Common Weight Loss Myths to Debunk

I had long been of the (outspoken) belief that yo-yo dieting, also referred to healthy eating pattern cycling, was bad. But, my eyes were figuratively opened when I heard an interview with Krista Casazza, Ph.D., associate professor in the Department of Pediatrics at the University of Alabama, on Danny Lennon’s podcast Sigma Nutrition Radio. (I highly recommend this podcast, by the way.) ³

In the interview, which centered on obesity myths, Professor Casazza cited a paper she co-authored titled Myths, Presumptions, and Facts about Obesity, published in the esteemed New England Journal of Medicine. ⁴Casazza and her colleagues busted such myths as:

• Small, sustained changes in caloric intake or expenditure produce large, long-term weight changes. (Not according to the research.)
• Setting realistic goals for weight loss is important because otherwise folks will become frustrated and lose less weight. (Hmmm…not necessarily.)
• Large, rapid weight loss is associated with poorer long-term weight-loss outcomes compared to slow, gradual weight loss. (The opposite is often true.)
• It’s important to assess the stage of change or diet readiness to help folks who are looking for weight-loss help. (This can be a helpful step for a coach to take.)
• Physical education classes, in their current form, play an important role in reducing or preventing childhood obesity. (They don’t.)
• A bout of sexual activity burns 100 – 300 calories for each participant. (It doesn’t.)

Surprised that some of these long-held beliefs are actually myths? To some extent, I was too, although personal coaching experience does provide some evidence to the contrary.

Casazza and her 19 fellow co-authors went on to call out presumptions, which they defined as widely accepted beliefs that have neither been proved nor disproved. Among the six presumptions included the value of breakfast, early childhood habits and weight, the value of fruits and vegetables, snacking and weight gain, and you guessed it, weight cycling.

While observational studies had suggested that weight cycling was associated with increased mortality, there was no solid evidence that yo-yo dieting itself increases the mortality rate. Rather, any observational findings were likely confounded by health status. Casazza and another group of esteemed researchers followed up this seminal paper a couple years later with another paper that thoroughly evaluated the research and came to the same conclusion. That is, beliefs surrounding weight cycling are presumptions. ^4, 5

Common Myths About Yo-Yo Dieting

While I do my best to keep an open mind—and the conclusions of these papers were certainly eye-opening for me—I wanted to take a deeper dive. After all, if you ask your friend Google what yo-yo dieting does to your body, you’ll quickly come to the conclusion that weight cycling wreaks havoc on your health, increasing your risk of obesity, diabetes, heart disease, cancer, and more.

Sounds pretty scary, doesn’t it?

Now, if one wants to “cherry-pick” through the research, it would certainly be possible to find evidence to support the preconceived belief that yo-yo dieting is detrimental to health. However, when we look at the totality of evidence, it is inconsistent at best. And actually, the negative connotations and long-standing beliefs associated with weight cycling do not seem to be supported by research.

Myth 1: Yo-yo dieting increases mortality

One of the most pervasive (and scary) beliefs about yo-yo dieting is that it increases the rate of mortality. In other words, it’s often said that weight cycling increases the risk of death. In one very large study published in the American Journal of Epidemiology, a group of researchers set out to actually assess the association of weight cycling with death among a sample of over 120,000 men and women for 16+ years. The researchers kept tabs on weight cycles (defined as intentional weight loss of 10 or more pounds followed by regain of that weight), and of course, how many people died. ⁶

After adjusting for body mass index and other risk factors, the researchers concluded, “These results do not support an increased risk of mortality associated with weight cycling.” In fact, the study showed that even high numbers of weight cycles (we’re talking 20 or more during the time period) did not increase the risk of mortality. And perhaps surprisingly, the researchers found that low numbers of weight cycles (1 – 4) were associated with slightly lower risk of death.

In a study published in the journal Obesity Reviews, a group of researchers from the University of Alabama (including Professor Casazza) undertook the task of reviewing human and animal studies to identify the potential detrimental effects of weight cycling. Their comprehensive evaluation led them to conclude, “Although weight regain following successful weight loss remains one of the most challenging aspects of body weight regulation, evidence for an adverse effect of weight cycling appears sparse, if it exists at all.” ⁷

Myth 2: Yo-yo dieting negatively affects obesity and metabolism

As an update to a 1994 review conducted by the National Task Force on the Prevention and Treatment of Obesity (which concluded that weight cycling did not impact metabolism), a recent review study published in the journal Obesity Research & Clinical Practice set out to address the common belief among the general community that yo-yo dieting is associated with adverse effects on obesity and metabolic risk factors. ⁸

Their findings showed that yo-yo dieting had no effect on the risk of type 2 diabetes. And their analysis revealed inconclusive evidence that a history of weight cycling influences body composition (e.g., increased body fat) or predisposes one to future obesity. They concluded, “The available evidence so far suggests that there is little detrimental effect of weight cycling on current and future obesity and metabolic risk, and therefore, weight-loss efforts in individuals with overweight/obesity should continue to be encouraged.”

Of course, many people mistakenly believe yo-yo dieting “damages” metabolism and leads to unfavorable changes in body composition—resulting in disproportionately large losses in calorie-burning lean mass with subsequently higher regains in body fat. Fortunately, this does not appear to be the case. Studies have shown that weight cycling neither leads to progressive decreases in metabolic rate nor to unfavorable body composition (e.g., increased proportion of body fat, decreased proportion of lean mass). ^9,10

Myth 3: Yo-yo dieting has a long-term effect on healthy markers

In a very recent study published in the journal Nutrients, a group of researchers led by Professor Wayne Campbell (who was one of my former undergraduate professors) of Purdue University were interested in better understanding what yo-yo dieting does to your body. ¹¹ In the study, participants ate either a Mediterranean-style or DASH-style diet for 5 – 6 weeks followed by a 4-week unrestricted eating period, which was once gain followed with a 5- to 6-week period of eating a Mediterranean or DASH diet.

Basically, the researchers were looking at what happens when folks adopt, abandon, and re-adopt healthy eating patterns. In particular, they were looking at cardiovascular disease risk factors, such as lipids, blood pressure, blood glucose, and insulin. As you might imagine, most of the variables improved, worsened, and then improved again when adopting, abandoning, and readopting the healthy eating patterns.

In other words, markers of cardiometabolic health follow a similar rollercoaster as one’s eating patterns. And perhaps the most important message is that as little as a few weeks of healthy eating can result in measurable improvements in markers of cardiometabolic health. I suppose if you’re a “glass half empty” kind of person, you might also say it doesn’t take long before they worsen (i.e., return to an unhealthy state).

According to Professor Campbell, “These findings should encourage people to try again if they fail at their first attempt to adopt a healthy eating pattern. It seems your body isn’t going to become resistant to the health-promoting effects of this diet pattern just because you tried it and weren’t successful the first time. The best option is to keep the healthy pattern going, but if you slip up, try again.”

What Yo-Yo Dieting Actually Does to Your Body

Rather than the presumption that weight cycling is bad for you, maybe a better way to summarize what yo-yo dieting does to your body is to say…

• Weight loss generally improves a battery of health markers and reduces a variety of risk factors.
• Weight gain and/or sustained obesity typically increases a variety of risk factors and leads to less favorable health
  biomarkers.

In other words, the health rollercoaster typically follows closely with the weight cycling rollercoaster. (There are, of course, exceptions. For example, the obesity paradox and the concept of metabolically healthy obesity.)

Yo-Yo Dieting is Better Than None?

Believe it or not, experimental research has shown that yo-yo dieting increases longevity compared with remaining obese. And weight cycling resulted in similar benefits compared to sustaining modest weight loss (at least in mice). ¹² These fascinating and intriguing findings led one group of scientists from the National Institutes of health to conclude that “weight cycling, or yo-yo dieting, is better than no dieting at all, at least in mice!” ¹³

And along those lines, the last thing we would want to do is dissuade someone from taking one more trip on the weight-cycling rollercoaster. This is a super-salient point because messages around weight loss are often muddled with the apparent risks of weight cycling. After all, that next weight-loss attempt could be the one that sticks.

Take that to heart, especially if you have had any history as a yo-yo dieter. You should never be discouraged from taking steps to improve your health. And certainly, don’t let scare tactics about weight cycling prevent you from giving it another shot.

This is an important message for healthcare professionals also. Of course, healthcare professionals should encourage folks to consistently follow healthy eating patterns as part of an overall healthy lifestyle, but they (we) should also encourage them to try again if a first (or second, third, etc.) attempt was unsuccessful or short-lived.

An Important Word of Caution

Okay, so maybe yo-yo dieting isn’t as bad for your body as you (or I) might have thought. But even if something isn’t bad, does that make it right? In other words, weight cycling is not without peril.

Dieting and weight cycling are not limited to folks who are obese or overweight (who are most likely to benefit from improved eating behaviors and lifestyle and subsequent weight loss). Substantial proportions of various population groups with normal, healthy body weight also attempt to diet and lose weight. These include:

• Young and older adults as well as children and adolescents who perceive themselves to be too fat (often the result of media, parent, and social pressures)
• Athletes in weight-sensitive competitive sports (with mandatory weight categories, gravitational and aesthetic sports)
• Performers for whom a slim image is professionally advantageous

Beyond the obvious psychological and emotional concerns, there is emerging evidence that some of the potentially negative health consequences of yo-yo dieting are more readily seen in people of normal body weight rather than in those who are overweight or obese. Of particular concern in lean folks who weight cycle are fluctuations of cardiovascular risk variables, such as blood pressure, heart rate, sympathetic nervous system activity, blood glucose, insulin, and lipids, not to mention a propensity toward enhanced weight gain/regain.

What Can We Learn from Yo-Yo Diets?

So, what have you learned from all this? Hopefully, you are walking away with a handful of important take-aways:

• Yo-yo dieting probably isn’t nearly as detrimental as you’ve likely been led to believe.
• Weight cycling does not appear to damage metabolism nor lead to unfavorable changes in body composition.
• However, some populations (especially lean folks who don’t need to “diet”) might be particularly sensitive to the potential negative effects of weight cycling.
• Generally speaking, health variables typically follow patterns of eating. In other words, healthy eating patterns (which typically involve weight loss) beget better health. On the other hand, unhealthy eating behaviors (which typically involve weight gain) lead to unfavorable health outcomes and increased risk for disease, death, etc.

Perhaps most importantly, if you’re a yo-yo dieter and you’ve found yourself on that weight-cycling rollercoaster in the past, don’t give up and don’t get discouraged. Yo-yo dieting seems to be better than no dieting at all. The last thing I want you to do is to be dissuaded from giving healthy eating another shot because of what you’ve heard about yo-yo dieting.

And to help you do everything you can to make sure the next effort sticks, here are some tips:

• Lose the label. If you’ve been on the weight-cycling rollercoaster, chances are you (or someone you know) have labeled yourself a yo-yo dieter. That’s a self-fulfilling prophesy. As long as you wear the scarlet letter, the likelihood is high that history will repeat itself. Ditch the label and think of yourself as a healthy eater. Visualize the person you want to become and DO everything that person would do (not what a yo-yo dieter would).

• You are enough. If you take nothing else from this, I urge you to remember this one thing: You are enough. Don’t worry about anybody else—what they’re doing, what they look like, etc. You are absolutely perfect right now—who you are and what you have to give to this world. Now, if you want to ramp up what and how much you can give to the world, then do a little extra to be healthier, feel better, and take care of that body of yours.

• Life’s lessons. Everything happens for us—not to us. What can you learn from your previous experiences? In other words, what has worked for you in the past? What challenges have you faced? How can you plan better in the future given what you know about your history?

• Get support. One of the biggest challenges people face (often unknowingly) is a lack of social support and accountability. In other words, they’re not surrounded by positive, like-minded folks who encourage, inspire, and motive them; who help hold them accountable; and who share similar triumphs and challenges. If you can’t find a supportive group of friends near you, join an online community, such as our Private VIP Facebook Community.

• Take it at your own pace. Some people do better by starting a simultaneous program (involving multiple changes at once) while others do better with a sequential approach (implementing one change at a time). Find what works best for you. Chances are you have some past experience, so make sure you refer to that. For example, if very restrictive diets “worked” (you lost a lot of weight) and then “didn’t” (you gained it all back), consider a different approach. Or, if the slow and steady approach just frustrates you, try something a bit more aggressive. Overall, though, if you want this to be your last ride on the weight-cycling rollercoaster, you will need to come up with a long-term plan that works for you.

• Do it smart. Even though there’s no substantial evidence to support the notion that weight cycling damages the metabolism or leads to excessive muscle loss, I suggest doing everything you can to maintain and/or build your muscle mass, including eating a healthy amount of protein most days and doing some strength training a couple days a week.

• What’s your WHY. If you want this to be your last trip on the weight-cycling rodeo, then you need to clearly establish why this is so darn important to you. What’s the real reason you are seeking to make a change?

Mini-Yo-Yo Dieting?

One important lesson we can tease out from yo-yo dieting is the idea of micro diet cycles, or intermittent dieting. Instead of longer, periodic up-and-down weight cycles, I’m talking about periodic fasting cycles. Yes, most people simply refer to this as intermittent fasting, which basically involves longer-than-normal periods of fasting (12 – 16 hours up to multiple days) with periods of normal eating (or even relative overeating).

There’s no ignoring the emerging body of scientific evidence suggesting the potential beneficial effects of intermittent fasting. And one of the many lessons that fasting research has shown us is that intermittent caloric restriction—or, what I’m calling intermittent dieting—is just as effective (if not more so) for weight loss as the traditional method of daily/continuous energy restriction.

The reality is that it’s about your behavior, on average, over time. Some days, you can eat more; others, less.

An added bonus of intermittent dieting and periodic fasting is that the only restriction is when you eat—not what or how much (although I always urge that the what matters too).