Healthy habits were linked to less disease, even without weight loss.

Cohort study. 142,041 people. average follow-up 17 years (3 million person-years); baseline 1990 (NHS, HPFS) / 1997 (NHSII), follow-up to June 2016/2017.

People were watched for years. Nobody was told what to do. A clue, not proof.

Who: US female nurses and male health professionals, 80% women, 96% non-Hispanic White, mean age 50 at baseline, free of chronic disease at start

• Adult-life habits-46%top vs bottom 10%
• Taken up in midlife-34%linked, not proven
• After weight change-26%midlife habits

More to know, from our read of the paper:

• Observational: linked, not proven. Residual confounding possible; sleep, finer socioeconomic data, stress and depression were not adjusted for (authors: for diabetes and heart disease these would tend to inflate the protective link)
• Habits were self-reported (questionnaires on recreational activity every 2 years, 130-item food frequency questionnaire every 4 years); BMI from self-reported height and weight
• Population: mostly non-Hispanic White health professionals with higher health literacy than average; preventable fractions assume the risk ratios transfer to the whole US population
• Main comparison is extreme deciles (top 10% vs bottom 10% of BOTH activity and diet). 'Optimal' activity = 47 MET-h/week, about 600 min/week of moderate activity, far above guidelines
• Part of the benefit ran through weight: cumulative BMI 'mediated' about 52% of the combined adult-habit effect and weight change about 27% of the midlife effect (approximation, difference-in-coefficients method). So: not 'weight doesn't matter', but 'benefit beyond weight'

Researchers followed 142,041 US nurses and health professionals (80% women, 96% white, average age 50) for about 17 years. People with the highest self-reported exercise and diet-quality scores had 46% lower risk of type 2 diabetes, heart attack, stroke or cancer than those with the lowest. Habits taken up in midlife were linked to 34% lower risk, and still 26% lower after accounting for weight change. Each extra 30 minutes a day of moderate activity was linked to 10% lower risk. This is observational: linked, not proven.

We read the abstract and the full text of this paper and checked every number on this page against it (16 facts, checked on 2026-10-29). The study design is named above. Cohort and other observational studies are described as linked, not proven. Found an error? Email theis@onestudyaday.com.