The Physiological Effects of Weight-Cycling: A Review of Current Evidence

PURPOSE OF REVIEW

There is a common perception among the public that yo-yo dieting, defined as repeated cycles of weight loss followed by weight regain, results in accumulation of fat in the body and lower metabolic rate, thus hindering subsequent attempts to lose weight. We evaluated the effects of weight-cycling on body weight and body mass index (BMI), body composition including fat mass (FM) and lean body mass (LBM), and resting metabolic rate (RMR), by systematically reviewing existing scientific literature.

RECENT FINDINGS

Twenty-three cross-sectional and cohort studies (including subjects with a history of weight-cycling compared to those without such history) and interventional studies (evaluating physiological effects during one or more cycles of weight loss and regain) were identified, conducted in generally healthy adults across various age groups, races, and both genders, who had normal weight, overweight, or obesity. Eighteen studies investigated the association between weight-cycling and body weight or BMI, and thirteen of them found no significant association. Fifteen out of twenty studies also found no increase in FM, and none of eighteen studies found a decrease in LBM. Twelve out of fourteen studies reported no adverse changes in RMR either. The overwhelming majority of evidence suggests that weight-cycling (yo-yo effect) is not associated with any adverse effects in body weight, body composition, and metabolic rate. Accordingly, healthy individuals who struggle with overweight or obesity should not be discouraged from repeated attempts to lose the excess weight.

Weight Cycling and Its Cardiometabolic Impact

Dieting has multiple meanings including "intentional weight loss" or "a specific eating pattern." Although obesity is considered a deleterious health problem worldwide, there are many problems caused by "too strict" weight control and the need for excessive leanness. Many people with normal weight want to lose weight, and they repeat losing and gaining weight multiple times through their lives. This is called "weight cycling." Recent studies report not just the negative impact of being obese, but also the danger of weight cycling for cardiometabolic health. Many experimental studies support that weight cycling might cause fluctuations in cardiovascular risk factors, such as blood pressure, heart rate, sympathetic activity, and circulating levels of glucose, lipids and insulin. These repeated overshoots above normal values during periods of weight regain put an additional stress on the cardiovascular system. This paper reviews current evidence for the effects of weight cycling on cardiometabolic health.