Lose Weight Without Counting Calories? Study Points to Food Choice

By Tahani Elghazaly
Published September 6, 2026

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A recent study suggests that weight loss may not always require daily calorie counting. Researchers found that people following a low-fat vegan diet rich in low-energy-density foods naturally consumed fewer calories even though they were not instructed to restrict their calorie intake or reduce the amount of food they ate. The analysis was published in JAMA Network Open in August 2026.

The research used data from a randomized clinical trial involving 244 adults with overweight. Half were assigned to a low-fat vegan diet based largely on fruits, vegetables, grains and legumes for 16 weeks, while the other half continued their usual diets. Neither group was given a prescribed calorie limit.

Among the 223 participants who completed the study, the overall weight of food consumed did not significantly decrease. However, energy intake fell substantially more in the vegan group, with a between-group difference of about 357 calories per day.

Researchers linked the change to dietary "energy density," the number of calories contained in each gram of food. Energy density fell by approximately 30% in the vegan group while remaining largely unchanged in the control group.

Foods that contain more water and fiber, including many vegetables, fruits, legumes and grains, can provide a larger volume of food for fewer calories than many high-fat foods. Lower energy density was associated with greater weight loss in the study.

The original clinical trial found that participants assigned to the low-fat vegan diet lost an average of about 5.9 kilograms over 16 weeks and also showed improvements in insulin sensitivity and other metabolic measures.

The findings do not mean calories are irrelevant or that every plant-based food promotes weight loss. The researchers also noted limitations, including the use of self-reported food records and a volunteer population that may not represent the wider public.