Research

Hormonal

In obese humans, circulating leptin levels are elevated while ghrelin levels are decreased, and the body exhibits leptin resistance, meaning high leptin fails to suppress food intake or increase energy expenditure as it does in lean individuals.

If you are obese, your body likely has high levels of leptin (the 'stop eating' hormone) and low levels of ghrelin (the 'start eating' hormone), but your brain has become resistant to these signals. This is why standard dieting often fails; your body fights back by ignoring the satiety signals. Understanding this resistance explains why simply 'trying harder' is physiologically difficult and why treatments must address the signaling pathway, not just hormone levels.

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In obese subjects the circulating level of the anorexigenic hormone leptin is increased, whereas surprisingly, the level of the orexigenic hormone ghrelin is decreased. It is now established that obese patients are leptin-resistant.
Melanie D. Klok et al. · Obesity Reviews · 2006

Why this rating

The paper is a comprehensive review citing multiple studies establishing these correlations and the concept of resistance.

Source

The role of leptin and ghrelin in the regulation of food intake and body weight in humans: a review

Melanie D. Klok et al. · Obesity Reviews · 2006

DOI 10.1111/j.1467-789x.2006.00270.x

narrative_reviewCited 1,434×
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DOI resolved against Crossref · corpus check 2026-06-10

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