Why some people can't lose weight even when they eat less and exercise
About Unsuccessful Responders to Diet and Physical Activity Interventions: A Focus on Energy Balance and Body-Weight Loss
Not medical advice. For informational purposes only. Always consult a healthcare professional. Terms
Surprising Findings
People can gain weight while in a strict 1000-calorie daily deficit under lab-controlled conditions.
Common belief is that a calorie deficit always leads to weight loss—this study proves biology can override physics in some individuals.
Practical Takeaways
Stop blaming yourself if you're not losing weight—try working with a specialist who tests for metabolic adaptation, thyroid function, or genetic markers.
Not medical advice. For informational purposes only. Always consult a healthcare professional. Terms
Surprising Findings
People can gain weight while in a strict 1000-calorie daily deficit under lab-controlled conditions.
Common belief is that a calorie deficit always leads to weight loss—this study proves biology can override physics in some individuals.
Practical Takeaways
Stop blaming yourself if you're not losing weight—try working with a specialist who tests for metabolic adaptation, thyroid function, or genetic markers.
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.