A recent study published in the European Journal of Preventive Cardiology shows that following a healthy diet can improve health even without losing weight. Researchers from Harvard T.H. Chan School of Public Health in the U.S. and Ben-Gurion University of the Negev in Israel analyzed data from 761 adults with abdominal obesity who took part in three long-term clinical trials.
Participants followed various healthy diets for 18 to 24 months, including the Mediterranean diet, green Mediterranean diet, low-fat, and low-carbohydrate diets. While 36% of participants achieved significant weight loss, many others experienced health benefits without shedding pounds. Nearly one-third of the group did not lose any weight, and 28% were resistant to weight loss, yet still showed improvements in health markers. These benefits included a reduced risk of type 2 diabetes, high blood pressure, and cardiovascular diseases.
“We have been taught to think that without losing weight there is no health, but this study demonstrates the opposite,” said researcher Anat Yaskolka Meir. “Real improvements can be achieved even if weight does not change.”
Weight loss was linked to improvements such as higher levels of good cholesterol (HDL), lower triglycerides, reduced insulin levels, decreased liver fat, and lower blood pressure. Each kilogram lost was associated with a 1.44% rise in HDL cholesterol, a 1.37% drop in triglycerides, a 2.46% decrease in insulin levels, and a reduction of 0.49 units in liver fat.
However, even participants who did not lose weight showed important health gains. They experienced lower blood pressure, reduced liver enzymes, and a decrease in visceral fat—the harmful fat surrounding internal organs. This was true even for those who were resistant to weight loss.
The research team also used advanced genetic tools and epigenetic analysis to identify 12 specific DNA methylation sites. These sites can predict long-term weight loss and how someone responds to a diet. This suggests that resistance to weight loss may be rooted in biology rather than a lack of 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 resistant to weight change also had lower levels of leptin, a hormone that controls hunger, which meant they felt less hungry and had less dangerous visceral fat. These findings highlight that health improvements can occur through diet changes alone, challenging the idea that weight loss must happen for dietary interventions to be successful.
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