Diet, lose weight, regain weight, repeat, repeat, repeat. Yo-yo dieting is an all-too-common phenomenon. More and more people are dieting — whether for weight loss or for “health” — even though most do not maintain their weight losses. This is unfortunate, because not only can yo-yo dieting lead to greater weight gain over time, but it may also put us in the path of heart disease and diabetes.
Even among people who lose a significant amount of weight — 10 percent or more — roughly 8 in 10 will regain that weight within a year. But dieting and yo-yo dieting are not limited to people at higher weights. National Health and Nutrition Examination Survey (NHANES) data shows that the percentage of dieters who weight in the normal range on the body mass index (BMI) chart is on the rise, currently almost 50 percent of women and 20 percent of men, while more than 10 percent of women with an underweight BMI report wanting to lose weight. Many adults, adolescents and children with normal or underweight BMIs diet because they feel pressure to be thinner.
Some of that external pressure may come from public health messages. “Terms like ‘war on obesity’ and obsession about slimness can backfire over the long-term,” said Abdul Dulloo, PhD, professor in the Department of Medicine/Psychology at the University of Fribourg in Switzerland. “The emphasis should not be about ‘body weight’ or ‘body fat’ per se, but about motivation for a healthy lifestyle in relation to food and physical activity.”
The very act of weight loss — especially the loss of muscle that accompanies all weight loss — triggers the body to fight back by increasing hunger, slowing metabolism and encouraging fat storage. This metabolic adaptation served our ancestors well during feast and famine, but not so much in today’s food environment, which encourages weight gain in people who are genetically predisposed to it. Repeated dieting attempts do nothing to reduce this vulnerability. Restricting food increases its appeal, which can leads to overeating, or even bingeing, and then weight regain.
Instead, what happens is fat overshooting — regaining more fat than was originally lost. The body wants to regain lost muscle, but regains fat first, so the drive to eat and slowed metabolism continue until muscle regain is complete. Overshooting after each cycle of weight loss and regain can contribute to an overall increase in weight over time. In fact, a recently published study in the journal Evolution, Medicine and Public Health proposes that the body’s uncertainty about food supply — and the body can’t tell the difference between intentional dieting and unintentional famine because of food shortages — may cause it to store more fat each time food restrictions are lifted than it would if food intake remained steady.
Other research supports this idea. A 2015 article in the journal Obesity Reviews co-authored by Dulloo suggests that lean dieters are at greater risk for fat overshooting than those who are classified as overweight or obese. The lower a dieter’s initial body fat percentage, the higher the proportion of muscle they lose and the higher the proportion of fat they gain. Over time, with continued yo-yo dieting, this may add up to a substantial increase in body fat. Two studies, in 2012 and 2013, of female twins found that the more frequent the cycles of yo-yo dieting, the greater the increase in body weight over time, especially among adolescents who start dieting at a lower BMI.
What’s more, yo-yo dieting in people who have BMIs at or below the normal range appears to increase risk of Type 2 diabetes, high blood pressure and heart disease. What about people who start dieting at a higher body weight? Research is inconclusive, in part because of varying definitions of yo-yo dieting used in studies. Some dieters may have one large loss and regain, while others may experience several smaller loss-regain cycles.
“Weight for all bodies, fat thin, normal/high BMI is not a thing that can be ‘controlled’ — it just can’t,” said Washington-area dietitian Rebecca Scritchfield, author of the book “Body Kindness.” “The only thing that can be controlled is choices, and you have to make choices that fit you best, work on meaningful habits that you can change.”
She suggests making a list of actions — or inactions — that are disappointing you and framing your goals around new actions that are in line with the person you want to be. Not sleeping enough? Skipping workouts? You can change that. Frustrated with how much alcohol you drink or how much you eat out? You can change that, too.
“Even if these things don’t lead to weight loss, if they make you happier they’re worth it,” she said. “You don’t want the only reason you’re taking on new health habits to be about weight loss. They’ll never stick. Habits should be about joy, energy and other things that help you every day.”
Dennett is a registered dietitian nutritionist and owner of Nutrition by Carrie.
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