When young healthy men consume 50% more calories than they burn, their resting metabolic rate rises, even if their physical activity levels stay the same.

When young healthy men eat fewer calories than they burn, their bodies burn slightly more energy at rest than expected based on the muscle they lose, suggesting other biological changes are contributing to this effect.

In physically trained men, a calorie deficit prevents any increase in resting metabolic rate, even when a lot of exercise is performed.

When young healthy men increase their physical activity by 50%, their total energy expenditure rises significantly, even if their food intake does not change, indicating that physical activity has a major influence on how much energy the body uses.

In trained men, resting metabolic rate increases only when both physical activity and food intake are high and balanced, not when calorie intake is higher or lower than expenditure alone.

In physically trained men, performing intense exercise for 90 minutes a day over three days while maintaining normal calorie intake is linked to a higher resting metabolic rate compared to days without exercise, even when calorie intake is unchanged.