Previous studies in humans and animals have focused on the short-term effects of weight loss, but a little is known about how weight loss and gain cycles (yo-yo dieting) can affect long-term health, researchers say.
For the study, the researchers divided 16 rats into two groups. One group received a normal diet throughout the study, while the other group received a yo-yo dieting of restricted diet (60% of their normal daily food intake) followed by three weeks normal diet. At the end of the study, the researchers used ultrasound to assess heart and kidney functions in rats and blood tests to assess insulin sensitivity, which is 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. They also had more insulin resistance, which can be a cause for diabetes,” said Aline M. A. de Souza, PhD, a postdoctoral fellow at Georgetown University in Washington, DC, first author of the study. “Even though the animals look to be healthy after ‘recovery’ from the diet, their heart and metabolism are not healthy.“
These findings raise questions about public health in light of the COVID-19 pandemic, which means that those who have difficulty accessing food as a result of pandemic lockdowns and economic impacts face an increased incidence of heart diseases in the coming years using long-term impacts.
“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,” said 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.“
Although more research is needed to determine the biological mechanisms behind the findings and whether the patterns found in rats are being translated into humans, researchers speculate that changes in gene expression in response to caloric control may alter the biological pathways that regulate blood pressure and insulin metabolism.