Following a healthy diet can lead to health benefits, even without shedding pounds, according to a new study published in European Journal of Preventive Cardiology. The research, conducted by scientists from Harvard T.H. Chan School of Public Health in the United States and Ben-Gurion University of the Negev in Israel, analyzed data from 761 adults with abdominal obesity who participated in three long-term clinical trials.

Participants adhered to healthy diets for 18 to 24 months, including the Mediterranean diet, green Mediterranean diet, low-fat, and low-carbohydrate diets. The study found that across all clinical trials, 36% of participants achieved clinically significant weight loss, but many others experienced health benefits without losing weight. Nearly one-third of participants did not lose any weight at all, with 28% resistant to weight loss, yet they still reaped many health benefits, including a lower risk of diseases such as type 2 diabetes, hypertension, and cardiovascular conditions.

"We have been taught to think that without losing weight there is no health, but this study demonstrates the opposite. Real improvements can be achieved even if weight does not change," said researcher Anat Yaskolka Meir, according to a press release published on EurekAlert.

Weight loss was associated with a variety of health improvements, including increased levels of good cholesterol and decreased triglycerides, insulin levels, liver fat, and blood pressure. Each kilogram lost was associated with a 1.44% increase in HDL cholesterol, a 1.37% decrease in triglycerides, a 2.46% decrease in insulin levels, and a decrease of 0.49 units in liver fat.

However, even those who did not lose weight showed notable improvements in cardiometabolic markers. Participants who adhered to a healthy diet, including those who did not lose weight, exhibited reductions in blood pressure and liver enzymes. The amount of visceral fat, which is dangerous for organs, decreased among the participants, including those resistant to weight change.

The researchers utilized omics tools and applied epigenetic analysis, discovering 12 specific DNA methylation sites that strongly predict long-term weight loss and how an organism will respond to a diet. This finding demonstrates that some people may be biologically wired to respond differently to the same diet, indicating that resistance to weight loss may be a biological feature, not a consequence of insufficient willpower. "This isn't just about willpower or discipline—it's about biology. And now we're getting close to understanding it," said researcher Iris Shai.

Participants who were resistant to weight change had lower levels of leptin, the hunger hormone, leading to less hunger, and had less harmful visceral fat. These findings suggest that health improvements can be achieved through dietary changes even without weight loss, reshaping the understanding of clinical success in dietary interventions.

Co-authors included Lu Qi, Dong Wang, Liming Liang, Frank Hu, and Meir Stampfer.

Written with the help of a news-analysis system.