The claimEvidence A · guideline-tier
You can out-exercise a bad diet
The evidence
An hour of running burns about 500 kcal; a single doughnut is about 400. Diet drives weight loss (American College of Sports Medicine position stand, Donnelly 2013); exercise's main value is keeping muscle, heart and lung fitness, and keeping the weight off.
The mechanism, in brief
Weight is a metabolic question, not an aesthetic one. What matters is not just the number on the scale but where the fat sits. At the same weight, fat wrapped around the organs (the liver, pancreas and intestines) causes far more trouble than fat under the skin: it is linked to insulin working less well, higher…
Sources (1)
- The Global BMI Mortality Collaboration. (2016). Body-mass index and all-cause mortality: Individual-participant-data meta-analysis of 239 prospective studies in four continents. The Lancet, 388(10046), 776–786. IPD from 239 prospective studies (10.6 million people); primary analyses in 3.95 million never-smokers without chronic disease who survived 5 years. All-cause mortality lowest at BMI 20.0-25.0; HR 1.13 at 18.5-20, 1.51 at 15-18.5, 1.07 at 25-27.5, 1.20 at 27.5-30, 1.45 at 30-35, 1.94 at 35-40, 2.76 at 40-60; per 5 units above 25, HR 1.39 in Europe and east Asia, 1.29 North America, 1.31 Australia/NZ; stronger in younger people and men (abstract, PMID 27423262).