Nearly one-third of people who adopted and consistently followed a healthy diet didn’t lose any weight but still experienced significant health benefits, according to a new study led by researchers from the Harvard T.H. Chan School of Public Health and Ben-Gurion University in Israel. The study is published in the European Journal of Preventive Cardiology.
Despite no weight loss, these individuals saw measurable improvements in key cardiometabolic markers, including higher levels of HDL (“good”) cholesterol, lower levels of the hunger hormone leptin, and reduced visceral fat.
People have been conditioned to equate health with weight loss, and those who don’t lose weight are often seen as failures. However, these findings shift that narrative. Even without weight loss, people can improve their metabolic health and reduce long-term disease risk. That’s not a failure; it’s a message of hope.
Study researchers analysed data from 761 adults with abdominal obesity in Israel who took part in three landmark clinical trials (DIRECT, CENTRAL, and DIRECT-PLUS). Participants followed healthy diets—low-fat, low-carb, Mediterranean, or green-Mediterranean, for 18 to 24 months with high adherence and detailed metabolic tracking.
Across all trials and diet types, 36% of participants achieved significant weight loss (over 5% of body weight), another 36% lost a moderate amount (up to 5%), and 28% were classified as weight-loss resistant, either maintaining or gaining weight. Yet the weight-loss-resistant group, largely older individuals and women, still showed notable improvements in metabolic health. They experienced increased HDL cholesterol, lower leptin levels (which can reduce appetite), and reductions in visceral fat.
These are meaningful biological shifts that have real consequences for heart and metabolic health. The study demonstrates that a healthy diet offers benefits beyond the number on the scale.
Researchers also used advanced omics tools to identify 12 specific DNA methylation markers that strongly predict a person’s likelihood of losing weight long-term.
This breakthrough suggests that biology and not just willpower plays a major role in weight loss. That is why people respond so differently to the same diet. It’s rooted in their biology.
Source: Harvard T.H. Chan School of Public Health
Image Credit: iStock
