After losing weight through dieting, the body continues to use less energy during daily activities than expected, mainly because muscles become more efficient at performing work and the nervous...
Mechanism
Synthesis from 1 study
After losing weight, lower levels of leptin and thyroid hormone reduce nervous system activity, making muscles more efficient at doing everyday tasks like walking — so they burn fewer calories during movement than when resting (10.1002/oby.23703). This is why it’s harder to keep weight off: the...
Most probable mechanism
After losing weight, levels of leptin and thyroid hormone drop, which reduces signals from the nervous system that normally make muscles work harder during movement. This lets muscles do the same tasks — like walking — using less energy, so the body burns fewer calories during daily activity. This effect is stronger than the drop in calorie burn at rest, helping the body hold onto energy and making weight loss hard to maintain (10.1002/oby.23703).
Weight loss reduces plasma leptin and triiodothyronine (T3) levels, which are key signals of energy sufficiency (10.1002/oby.23703).
Low leptin and T3 decrease sympathetic nervous system activity, reducing neural drive to skeletal muscle (10.1002/oby.23703).
Reduced sympathetic tone improves skeletal muscle mechanical efficiency during submaximal physical activity, lowering the energy cost of movement (10.1002/oby.23703).
Improved muscle work efficiency causes a greater reduction in nonresting energy expenditure than in resting energy expenditure during weight maintenance, creating a persistent energy conservation state (10.1002/oby.23703).
Less supported by current evidence, but not ruled out
In the first days of dieting, the body burns through stored sugar and loses water bound to it, which reduces the energy needed just to keep basic body functions running (10.1002/oby.23703).
Caloric restriction lowers insulin and raises glucagon, triggering glycogen breakdown (10.1002/oby.23703).
Glycogen loss causes water to leave cells, reducing tissue mass and metabolic demand (10.1002/oby.23703).
This leads to an early drop in resting energy expenditure independent of fat or muscle loss (10.1002/oby.23703).
After prolonged dieting, the body shifts to burning fat and slows down the metabolism of key organs like the liver and kidneys, which lowers the energy needed for basic functions even after weight stabilizes (10.1002/oby.23703).
Glycogen stores are depleted, shifting energy use to fat mobilization (10.1002/oby.23703).
Metabolic activity in organs such as the liver, kidneys, and heart declines, measured by reduced urea production, glomerular filtration, and heart rate (10.1002/oby.23703).
Lower core body temperature and organ-specific metabolic rates contribute to sustained reductions in resting energy expenditure (10.1002/oby.23703).
Evidence from Studies
Supporting (1)
Community contributions welcome
Changes in body composition and homeostatic control of resting energy expenditure during dietary weight loss
Contradicting (0)
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Gold Standard Evidence Needed
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