Higher BMI was linked to some cancers. At 30 and at 65.

People say: “Is there one age when extra weight matters most?” We read the study.

What they did

Meta-analysis of cohort studies. 720,210 people. median follow-up 9.85 years (men) and 10.80 years (women).

Many studies, added up. People were watched, not told what to do. A clue, not proof.

Who: 720,210 adults (43% men, 57% women) from US and European cohorts with at least 3 BMI measurements; median age at entry 60.9 (men) and 63.0 (women); mean BMI 27.2 (men) and 26.9 (women)

What they found
  • Men, BMI at age 30+32%per 5 BMI points
  • Men, BMI at age 65+28%similar to age 30
  • Women, BMI at age 65+15%+14% at age 30
The catch

More to know, from our read of the paper:

  • Observational: linked, not proven. Heavy topic: calm tone, no blame
  • BMI at ages 30-65 was PREDICTED (mixed model from observed, self-reported or recalled BMI), not measured at each age; authors say this may hide age differences
  • Could not adjust for physical activity, diet, socioeconomic status or smoking pack-years (only ever/never); covariates fixed at study entry; survivor bias (had to be alive and cancer-free at each age)
  • Small age interactions in women (ages 35, 40: HR 1.04, 1.05) and rising postmenopausal breast cancer association are the 'sensitive period' signals; the main message is that associations were similar across ages 30-65
  • Cohorts are older US/European adults recruited decades ago; BMI distributions may not match today
The verdict

The link held at every age studied.

In short

Researchers pooled data from five large US and European studies: 720,210 adults followed for about 10 years. They estimated each person's BMI at ages 30 to 65. In men, every 5 extra BMI points at age 30 was linked to 32% higher risk of obesity-related cancers (such as bowel, kidney and pancreas), and 28% at age 65. In women it was 14% at age 30 and 15% at 65. The link was similar at every age studied. This is observational, and BMI at younger ages was estimated, not measured: linked, not proven.

The video
The paper

Hawwash NK, Sperrin M, Martin GP, Sinha R, Matthews CE, Schulze MB, Hiensch A, Amiano P, Neuhouser ML, Joshu CE, Platz EA, Freisling H, Gunter MJ, Renehan AG (2026). Sensitive Period Analysis of Adulthood BMI and Cancer Risk: An Individual Participant Data Meta-Analysis of Over 720,000 Participants in the ABACus 2 Consortium. International Journal of Cancer.

Design: Meta-analysis of cohort studies · two-stage random-effects individual participant data meta-analysis of 5 prospective cohorts (EPIC, ARIC, WHI, PLCO, NIH-AARP); BMI at ages 30-65 predicted from observed, self-reported or recalled measurements; landmark (sensitive period) Cox analysis (linked, not proven)

DOI: 10.1002/ijc.70464

Goals:

Healthy old age
How we checked

We read the abstract and the full text of this paper and checked every number on this page against it (17 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.

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