WASHINGTON — Yo-yo dieting increases the risk of heart disease and diabetes, warns new research. The study conducted in rats suggests that dramatic swings in calories consumed have long-term impacts on cardiovascular health and metabolism.
Scientists at Georgetown University say that their findings offer potential insights into the long-term impacts of weight-loss diets, as well as involuntary reductions in food intake caused by food insecurity. Most previous studies in humans and animals have focused on the short-term impacts of weight loss, but less is known about how cycles of weight loss and gain may affect long-term health.
For the new study, researchers divided 16 rats into two groups. One group received a normal amount of food throughout, while the other group experienced three cycles of a restricted diet: 60 percent of their normal daily food intake, followed by three weeks of a normal diet. At the end of the study period, the research team used ultrasound to assess the rats’ cardiac and renal functioning and blood tests to assess insulin sensitivity, a measure of how the body processes sugar.
“We found that animals going through several cycles of weight loss and body weight recovery had reduced heart and kidney function at the end,” says study first author Dr. Aline de Souza, a postdoctoral fellow at the university, in a statement. “They also had more insulin resistance, which can be a cause for diabetes. Even though the animals look to be healthy after ‘recovery’ from the diet, their heart and metabolism are not healthy.”
She says the findings also raise questions about public health in light of the COVID pandemic, such as whether people who had trouble accessing food as a result of lockdowns and economic impacts face increased risk of cardiovascular problems in the years ahead.
“Our data supports the need for additional research in people to find out if individuals who do cycles of very restrictive diets to lose weight are at higher risk of developing heart problems later in life,” says de Souza. “We still need to do more studies in this field but the findings suggest the more restrictive the diet is, the worse the health outcomes may be. Weight loss diets need careful consideration of long-term health, especially if rapid weight loss is being contemplated as an option.”
The researchers believe that changes in gene expression in response to caloric restriction could alter biological pathways that regulate blood pressure and insulin metabolism.
Dr de Souza presented the findings at the American Physiological Society annual meeting in Philadelphia.
South West News Service writer Stephen Beech contributed to this report.