Repeated weight loss journeys are often referred to as “yo-yo” diets or “weight cycling” and have gained a reputation for being bad for our health, potentially making future battles with the bulge even more challenging. But a recent review of decades of evidence finds that yo-yo dieting is not responsible for greater fat accumulation, rapid muscle loss or a slower metabolism.
Review, published in The Lancet, The aim was to find out whether the old adage that yo-yo dieting is bad for our health is based on science, or merely a matter of opinion. To set the record straight, two distinguished professors looked at decades of study data, involving both humans and animals, and concluded that there was no causal evidence to show any link between weight cycles and long-term harm in people living with obesity.
“Many people struggling with weight are discouraged from trying to lose weight because they fear that ‘yo-yo dieting’ will lead to muscle loss and somehow harm their metabolism.” Professor Fedon Magakos commented. “Our review indicates that these fears are largely unsupported. In most cases, the benefits of trying to lose weight clearly outweigh the theoretical risks of weight cycling.”
Is yo-yo dieting bad for your health?
The review found no consistent evidence to show that cycling with weights causes a disproportionate loss of lean muscle or long-term suppression of metabolism. Instead, most people who gain weight after yo-yo dieting return to a similar starting point, going back to their previous body composition rather than becoming unhealthy.
Professors say that regaining weight reverses many of the benefits of weight loss, such as improvements in blood sugar, blood pressure and lipid levels. But this does not mean that a person’s condition is worse than before losing weight. “Weight regain brings people back to baseline risk — not any further,” Magakos explained. “There is an important difference between losing profit and causing harm.”
Professor Norbert Stephan said that although yo-yo diets may be to blame, other factors play a role. They concluded, “Once you properly account for pre-existing health conditions, aging, and the overall risk of obesity, the purported harmful effects of weight cycling largely disappear.”
When average body weight over time is considered, weight cycling does not predict diabetes or heart disease risk. High obesity, not weight fluctuations, appears to be the major driver of such risk.
Now that people are starting to take and stop GLP-1 medications, the effects of yo-yo dieting are of great interest. “The idea that ‘yo‑yo dieting ruins your metabolism’ is not supported by strong evidence,” is the take-home message stressed by both professors. “Trying to lose weight – and even failing – is not harmful. But giving up completely can be harmful.”
