The Study
Metabolic and appetitive regulation of adipocyte mass during treatment of obesity
This article is like a science teacher explaining how the body might keep weight stable, using stories from other studies. It doesn't do any new experiments, so we can't say for sure that any one thing causes weight gain or loss — it just suggests how it might work.
Analysis score
Maximum 5 for a narrative review.
Where the score came from
Your body thinks it's starving when you lose weight, so it slows your metabolism and makes you hungrier to get back to your old weight — even if that weight is too high.
Where does this study sit?
Reviews of RCTs (Meta-analyses)
Max 100Randomized Trials
Max 90Reviews of Cohort Studies
Max 85Cohort Studies
Max 72Reviews of Case-Control Studies
Max 63Case-Control Studies
Max 58Cross-Sectional & Case Series
Max 50Expert Opinion
Max 51 / 100
Quality score
Systematic reviews and meta-analyses of cohort studies. They sit above a single cohort study but below a single randomized trial, because the underlying evidence is still observational.
Key takeaways
Summary
Based on the study abstract and findings.
- 1This means most people regain weight on diets alone because their biology fights them — not because they lack willpower.
- 2After losing weight, your body burns 15%–20% fewer calories than expected, and you feel hungrier because hunger hormones go up and fullness hormones go down.
Score breakdown, methodology, conflicts of interest, evidence analysis & raw study data
Publication
Journal
Journal of Internal Medicine
Year
2025
Authors
J Q Purnell, C. L. le Roux
Related Content
Claims (6)
Calorie-restricted diets lead to increased hunger signals that prevent most people from keeping off lost weight.
In people with obesity, diet and exercise alone typically lead to only a small amount of weight loss—2% to 4% after 10 years—because the body's biological systems resist sustained reductions in fat mass.
After people with obesity lose weight, their bodies burn 15% to 20% fewer calories per day than expected based on their new lower weight, which makes it harder to maintain the weight loss without eating even fewer calories.
After people with obesity lose weight, their bodies produce less of the hormones that signal fullness and more of the hormone that signals hunger when they eat the same meal they ate before losing weight, which increases hunger and contributes to regaining weight.
In people with obesity, reduced sensitivity to the hormone leptin causes the brain to maintain a higher body weight as the normal set point, resulting in lower energy use, changes in gut hormones, and increased hunger that prevent sustained weight loss and encourage weight regain.
Obesity medications and metabolic-bariatric surgery cause lasting weight loss by changing how the brain detects fat stores, which lowers hunger and blocks the body's natural adjustments that usually restore lost weight after dieting.
Not medical advice. For informational purposes only. Always consult a qualified healthcare professional before making health decisions.