You don’t have to lose weight to get healthier.
That’s the key message from a new Harvard-led study published in the European Journal of Preventive Cardiology, showing that people who adopted a healthy diet saw major improvements in heart and metabolic markers, even if the number on the scale didn’t budge.
Researchers analyzed long-term data from over 750 adults with abdominal obesity who followed low-fat, low-carb or Mediterranean-style diets. Nearly 30% of participants lost no weight but still showed signs of better cardiometabolic health: improved HDL (“good”) cholesterol, lower hunger hormone levels and reductions in deep belly fat.
“People who do not lose weight can improve their metabolism and reduce their long-term risk for disease. That’s a message of hope, not failure,” said lead author Anat Yaskolka Meir, a postdoctoral research fellow at Harvard T.H. Chan School of Public Health.
The findings challenge the idea that weight loss is the only, or most important, marker of success when it comes to diet. According to the study, people resistant to weight loss were more likely to be older or female, but they still experienced meaningful internal changes that can reduce disease risk.
Researchers also identified 12 DNA methylation sites — biological markers that help predict long-term weight loss response — suggesting that how we respond to diet may be influenced by genetics, not just willpower.
“This isn’t just about willpower or discipline — it’s about biology,” said co-author Iris Shai, principal investigator of the original trials.
While more research is needed, the takeaway is clear: healthy eating habits can make a difference, regardless of whether they show up on the scale.
This research was supported by the German Research Foundation.