Participants who adopted a low-fat vegan diet ate about the same total weight of food each day as before, but their calorie intake fell roughly 357 calories a day further than the control group's, because the food they were eating carried about 30% fewer calories per gram. The finding comes from a secondary analysis of a randomized clinical trial published in JAMA Network Open.
The result identifies a mechanism rather than a new diet. The researchers measured dietary energy density, calculated for each participant as total daily calories divided by total daily food weight in grams. Energy density did not change in the control group. It fell about 30% in the group following the vegan pattern, and total food weight did not change significantly in either group.
