Engaging in 3,000 kilocalories of aerobic exercise per week leads to reductions in body fat percentage and fat mass in overweight adults, without changing resting metabolic rate or overall daily...
Mechanism
Synthesis from 1 study
People who did a lot of aerobic exercise burned more calories, but their bodies didn’t slow down or make them eat more to make up for it. Because they kept burning more than they consumed, their bodies had to use stored fat for energy, which led to less body fat. The changes in hunger hormones...
Most probable mechanism
When a person does a lot of aerobic exercise, they burn more calories than usual. Their body doesn’t slow down how much energy it uses at rest or overall during the day, and they don’t eat significantly more. So the extra calories burned from exercise aren’t made up for — this creates a calorie shortfall, and the body uses stored fat to make up the difference, leading to less body fat.
Aerobic exercise increases total energy expenditure, creating a transient energy deficit
Resting metabolic rate remains unchanged despite the increased energy expenditure
Total daily energy expenditure does not increase proportionally to offset the exercise-induced deficit due to lack of compensatory non-exercise activity changes
Energy intake does not increase sufficiently to match the energy deficit created by exercise
The persistent energy deficit leads to mobilization of stored triglycerides from adipose tissue for fuel
Mobilized fatty acids are oxidized in muscle and liver tissues, resulting in net loss of fat mass and reduced body fat percentage
Less supported by current evidence, but not ruled out
Exercise can change hormones that make you feel hungrier or less full, which might make you want to eat more, but in this case, those changes aren’t strong enough to make people eat enough to cancel out the calories burned.
Aerobic exercise increases circulating levels of acylated ghrelin, a hormone that stimulates hunger
Aerobic exercise decreases circulating levels of glucagon-like peptide-1, a hormone that promotes satiety
These hormonal changes act on hypothalamic appetite centers to increase hunger drive
Increased hunger drive does not result in sufficient energy intake to fully compensate for the exercise-induced deficit
Exercise might make food feel less rewarding, which could help prevent overeating — but this effect is unclear and may not be the main reason fat is lost.
Aerobic exercise reduces the reinforcing value of food in behavioral assays
Reduced food reinforcement may decrease food-seeking behavior and voluntary intake
This reduction in food motivation may contribute to insufficient energy intake to offset exercise expenditure
Evidence from Studies
Supporting (1)
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Energy compensation in response to aerobic exercise training in overweight adults.
Contradicting (0)
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