A few months ago, I received variations of this question from three different readers: “I get that diets usually don’t work in the long term, but does dieting actually lead to weight gain?” In other words, does dieting make you fat? (Note that I use “fat” as a neutral descriptor, like “tall” or “short.”) Research is increasingly finding that yes, it can — especially if you start dieting when you are already relatively thin but would like to be thinner.
Let’s face it, dieting in pursuit of weight loss is common among people of all body weights. Many adults, adolescents and even children with a body mass index in the “normal” or “underweight” ranges diet because they think they weigh too much or feel pressure from society, media, friends or family to be thinner. Data from the National Health and Nutrition Examination Survey shows that the percentage of people pursuing weight loss increased between 1999 and 2016, regardless of what their BMI was. And most dieters don’t maintain their losses — while estimates vary, research suggests that 80% of individuals who intentionally lose more than 10% of their body weight regain that weight within a year, and about 95% of people who lose weight gain it back within five years.
How many people do you know who go on one diet, lose weight, gain it back and decide to never diet again? Not many. That makes weight cycling — repeated cycles of intentional weight loss and regain — quite common. Also known as “yo-yo dieting,” weight cycling is characterized by metabolic adaptation to weight loss. In other words, your body deploys a combination of biological and hormonal forces to push your weight back to where it was. This adaptation benefitted our long-ago ancestors during times of feast and famine, but it predisposes modern humans to weight gain and increased risk of developing cardiovascular disease or Type 2 diabetes.
Why weight cycling happens
Dieting is essentially a semi-starvation state, and the body responds by slowing down its metabolism — burning fewer calories at rest, during exercise and for heat production (thermogenesis) — even after weight regain begins. It also increases our drive to eat — or even overeat. Psychologically, dieting and restriction increase the reward value of food. Physically, loss of lean muscle triggers the body to try to reverse course by increasing hunger and appetite levels.
All of this contributes to weight regain, but more critically, it can lead to “fat overshooting” — regain of more body fat than you originally lost. When you lose weight, you lose both body fat and muscle. When you start to regain weight, you regain body fat first, even though your body is striving to regain muscle. This means that by the time you have regained enough muscle, you’ve regained more fat than you originally lost — the “overshooting.” Weight cycling can cause “overshoot” of blood pressure, heart rate, blood sugar and cholesterol.
How weight cycling affects the body
The burning question is this: if someone weight cycles, is their risk of weight gain, diabetes and cardiovascular disease higher than it would be if they never dieted in the first place? Research has yielded mixed results, partly because the definition of weight cycling used in studies varies. For example, some dieters may experience one large weight cycle, while others may experience many smaller cycles.
A 2020 review in the International Journal of Obesity suggests that “normal” and “underweight” dieters are at the greatest risk for fat overshooting. The lower the dieter’s initial body fat percentage, the more muscle they lose and the more fat they regain. Cumulative fat overshoot over several weight cycles could add up to a substantial increase in body fat percentage. This is why dieting — especially repeat dieting — is a predictor of future weight gain, especially among younger dieters who start out relatively thin.
- A 2012 study published in the same journal followed 4,129 mostly “normal-weight” adolescent twins into young adulthood and found that the more frequent the weight cycling, the greater the increase in BMI. This association was strongest among adolescents who started dieting while in the lowest BMI category.
- A 2013 study from the University of Washington published in the journal Appetite involving 950 female twins ages 18 to 60 found that the younger age at first diet was associated with larger increase in BMI and more dieting behaviors and weight cycling episodes.
- One often-cited 1997 study in the International Journal of Sports Medicine found that healthy young men who lost 12% of body weight during a rigorous eight-week Army training course regained more weight — especially more fat — than they lost.
It’s worth noting that athletes in “weight-sensitive” sports that have strict aesthetic standards or weight categories — such as gymnastics, figure skating or wrestling — may weight cycle between seasons, starting as early as adolescence. Also concerning is that older adults who diet are not only more likely to regain fat than muscle — they may never fully regain lost muscle. Over time, especially with weight cycling, this could contribute to what’s known as “sarcopenic obesity” — low muscle mass with high fat mass — which can result in physical limitations and other health risks.
The bottom line
Even though the negative physical health effects of weight cycling appear to be more common in people who start dieting when they are already relatively thin, the psychological effects — food obsession, self-judgment, guilt and shame — are not limited to any particular body size. And repeated “failed” attempts to lose weight can drive people to pursue even more restrictive diets or other potentially risky weight loss methods. Or, they may give up on nutrition and physical activity because there’s no weight loss payoff. That’s a shame, because there are many things we can do to support physical and mental health that have nothing to do with manipulating body size. And that’s exactly what I’ll be talking about in next week’s column.
The opinions expressed in reader comments are those of the author only and do not reflect the opinions of The Seattle Times.