A healthy diet improves metabolism even without weight loss

A healthy diet improves metabolism even without weight loss

Nearly a third of people who adopted and stuck to a healthy diet didn't lose weight but still achieved many health benefits, according to a new study conducted by researchers at the Harvard Th Chan School of Public Health and Ben Gurion University, Israel. Regardless of weight loss, study participants showed significant improvements in cardiometabolic markers, including higher levels of HDL cholesterol (the healthy type of cholesterol), lower levels of leptin (the hormone that signals hunger), and less visceral fat (belly fat found deep in the abdominal cavity, sometimes around organs).

We have been conditioned to equate weight loss with health, and it is often labeled as failure. Our results will reset how we define clinical success. People who don't lose weight can improve their metabolism and reduce their long-term risk of disease. This is a message of hope, not failure. “

Anat Yaskolka Meir, senior author, postdoctoral fellow, Department of Epidemiology at Harvard Chan School

The study will be published on June 5th in theEuropean Journal of Preventive Cardiology.

Researchers analyzed changes in weight and health in 761 people with abdominal obesity in Israel who participated in three workplace mitigation clinical nutrition trials (Direct, Central and Direct) with high adherence rates and comprehensive metabolic profiles. In each study, participants were randomly assigned to adopt and adhere to healthy diets and adhere to low-fat, low-carbohydrate, Mediterranean, and green-Mediterranean diets between 18 and 24 months.

The study found that across all clinical trials and all diets, 36% of participants achieved clinically significant weight loss (defined as losing more than 5% of their initial body weight); 36% achieved moderate weight loss (up to 5% of their initial body weight); and 28% were resistant to weight loss, not losing weight or gaining weight. The weight loss was associated with a variety of health improvements: The researchers calculated that each kilogram lost was associated with a 1.44% increase in HDL cholesterol, a 1.37% decrease in triglycerides, a 2.46% drop in insulin, a 2.79% drop in leptin and a 0.49% drop in leptin, as well as a reduction in blood pressure Liver fat in the bleeding and a reduction in liver fat and the liver-liver fat in the bleeding and liver enzymes was associated.

However, the study also found that participants who were resistant to weight change were older and/or women attributed many of the same improvements. They had more good cholesterol; lower leptin levels, leading to less hunger; and less harmful visceral fat.

“These are deep metabolic changes with real cardiometabolic consequences,” said Yaskolka Meir. “Our study showed that a healthy diet works, even if your weight doesn’t shift.”

The researchers also used cutting-edge OMICS tools and discovered 12 specific DNA methylation sites that strongly predict long-term weight loss.

“This novel finding shows that some people are biologically wired to respond differently to the same diet,” said corresponding author Iris Shai, director of nutritional experiments and adjunct professor of nutrition at Harvard Chan School. "This isn't just about willpower or discipline-it about biology. And now we're getting closer to understanding it."

The study had some limitations, namely that the majority of participants were men. The researchers noted that future similar studies should focus on women.

Harvard Chan's other co-authors were Lu Qi, Dong Wang, Liming Liang, Frank Hu and Meir Stampfer.

The study was funded by the German Research Foundation (project 209933838).

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