Even though protein makes up a small and consistent portion of most diets, it might affect how much food people eat by influencing hunger and fullness, which could contribute to or reduce obesity.

When people eat a diet with only 10% protein, they tend to consume more calories overall because they eat more savory snacks between meals, not because they eat larger meals. This suggests that lower protein levels may trigger more frequent eating starts, not reduced fullness.

When lean adults reduce their protein intake from 15% to 10% of their daily calories, they tend to eat about 12% more calories over four days, mostly by snacking more on savory foods, suggesting that lower protein levels may lead to increased overall food consumption.

When people consume a diet with only 10% protein, they may eat more total calories, but their protein intake still remains lower than on higher-protein diets, suggesting the body does not fully adjust energy intake to restore protein levels.

When the proportion of protein in the diet is lowered from 15% to 10% of total calories, people tend to eat more total food to maintain their protein intake, resulting in higher overall energy consumption.

When lean adults increase their protein intake from 15% to 25% of daily calories, they do not eat fewer total calories over four days, indicating that the body adjusts energy intake when protein is too low but not when protein is too high.