Research
Energy balance
Sustained weight loss requires a permanent reduction in energy intake below the body's reduced energy expenditure, as metabolic adaptation lowers energy needs during weight loss.
To keep weight off, you must eat less than you did before you lost the weight, because your body burns fewer calories at a lower weight. This isn't a failure of willpower; it's biology. You need to permanently adjust your intake to match your new, lower energy needs.
StrongSupportsHIGH confidence
The challenge of sustainable weight loss, therefore, is to reduce food intake below the already low normal energy requirements and then to maintain a permanently lower energy intake afterwards to prevent weight regain.
Why this rating
Based on established physiological principles and meta-analyses cited in the text.
Source
Making progress on the global crisis of obesity and weight management
Michael E. J. Lean et al. · BMJ · 2018
DOI 10.1136/bmj.k2538
narrative_reviewCited 72×
Read the paper DOI resolved against Crossref · corpus check 2026-06-10
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