In overweight adults who are inactive, doing aerobic exercise that burns 3,000 calories per week for 12 weeks leads to measurable decreases in body fat, while exercising at half that energy...
Mechanism
Synthesis from 1 study
When you exercise hard enough, your body tries to make you eat more by changing hunger hormones. If you don’t exercise much, your body’s hunger signals are weak and don’t push you to eat more — so you still lose fat. But if you exercise just a little, your body makes you hungry enough to eat back...
Most probable mechanism
When you exercise a lot, your body senses you're burning more energy and responds by making you feel hungrier and less full, so you end up eating more without realizing it. If you don't burn enough energy, this hunger signal isn't strong enough to push you to eat significantly more, so you don't lose fat. But when you burn a lot — like 3,000 calories a week — your body still tries to make you eat more, but you end up burning more than you eat, so you lose fat.
Aerobic exercise increases energy expenditure, creating a transient energy deficit
The energy deficit stimulates increased secretion of acylated ghrelin from the stomach, which signals hunger to the brain
The energy deficit reduces secretion of glucagon-like peptide-1 from the intestines, which weakens satiety signals to the brain
Elevated acylated ghrelin and reduced GLP-1 act on hypothalamic appetite centers to increase hunger perception and reduce feelings of fullness
Increased hunger and reduced satiety lead to higher energy intake, partially offsetting the exercise-induced energy deficit
At 1,500 kcal/wk energy expenditure, compensation fully offsets the deficit, preventing net fat loss; at 3,000 kcal/wk, compensation is insufficient to fully offset the deficit, enabling net fat loss
Less supported by current evidence, but not ruled out
Exercise might make food seem more rewarding or tempting, causing people to eat more without feeling hungrier. But in this study, food reward actually decreased, so this is unlikely to be the main reason for compensation.
Aerobic exercise creates an energy deficit, triggering neurobehavioral changes in brain reward circuits
The energy deficit alters dopamine signaling in reward centers, increasing the motivational value of food
Increased food reinforcement enhances food-seeking behavior and energy intake to restore energy balance
In this study, food reinforcement decreased after training, contradicting the expected direction and suggesting this pathway is not dominant
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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