The Study
About Unsuccessful Responders to Diet and Physical Activity Interventions: A Focus on Energy Balance and Body-Weight Loss
This article is like a teacher telling a story about different kids who didn’t lose weight even when they ate right and exercised. It says, 'Hmm, maybe it’s because of their genes or how their body works,' but it didn’t test any of that. So we can’t say for sure why it happens — just that it sometimes does.
Analysis score
Maximum 5 for a narrative review.
Where the score came from
Even when people eat much less and exercise a lot, some still don't lose weight — or even gain weight — because their bodies react differently.
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 diet and exercise don't work the same for everyone — your genes and biology can make weight loss much harder, even if you do everything right.
- 2In controlled studies, people lost between 1 and 8 kg over 100 days on the same diet and exercise plan; twins lost similar amounts; 5–20% of people gain weight or don't lose any.
Score breakdown, methodology, conflicts of interest, evidence analysis & raw study data
Publication
Journal
Nutrients
Year
2026
Authors
Angelo Tremblay, Raphaëlle Jacob, Louis Pérusse, V. Drapeau
Related Content
Claims (4)
To lose body fat, you must consume fewer calories than you expend, and the size of this calorie deficit has a greater impact on fat loss than whether you do running, weightlifting, or other forms of exercise.
In obese adults following supervised diet and exercise programs designed to create a calorie deficit, 5% to 20% do not lose weight and may even gain weight, even when they follow the plan closely, suggesting that biological differences between individuals affect how well these standard approaches work.
When people follow identical strict diet and exercise regimens with a 1000 kcal daily deficit, they lose different amounts of weight—between 1 and 8 kg over 100 days—and identical twins tend to lose similar amounts, indicating that genetics may influence how the body responds to calorie restriction.
After losing a large amount of weight, the body continues to burn fewer calories at rest than expected based on its new size, and this persistent reduction in energy expenditure may make it harder to keep the weight off over time.
Not medical advice. For informational purposes only. Always consult a qualified healthcare professional before making health decisions.