Lancet Reg Health Am. 2026 Jun 27;61:101540. doi: 10.1016/j.lana.2026.101540. eCollection 2026 Sep.
ABSTRACT
BACKGROUND: Body mass index (BMI) is often treated as a proxy for lifestyle, but this may discourage people with higher BMI from adopting risk-reducing behaviors and lead those with lower BMI-including individuals achieving weight reduction through pharmacotherapy-to overlook the value of lifestyle. We aimed to estimate incidence of chronic disease preventable through physical activity and diet quality, independent of BMI.
METHODS: We followed 142,041 adults (80% [113,727] female, mean baseline age 50 years, 96% [136,998] non-Hispanic White) from the Nurses' Health Study, Nurses' Health Study II, and Health Professionals Follow-up Study. Physical activity was assessed as metabolic equivalent of task (MET) hours per week, and diet quality as modified Alternative Healthy Eating Index. Chronic disease included type 2 diabetes, major atherosclerotic cardiovascular disease, and cancer. Regression models adjusted for BMI at multiple life stages allowed estimation of effects for sustained adulthood habits and midlife changes, independent of prior BMI and lifestyle.
FINDINGS: Participants in the highest deciles of physical activity and diet quality had 46% (95% confidence interval [CI], 40-52%) lower risk of chronic disease for sustained habits and 34% (95% CI, 26-41%) for midlife changes. Results were similar among women (44% lower risk [95% CI, 35-51%] sustained habits, 32% [95% CI, 20-41%] midlife changes) and men (54% lower risk [95% CI, 41-64%] sustained habits, 48% [95% CI, 33-60%] midlife changes). The proportion of cases potentially preventable was 34% (95% CI, 27-41%), or 1.1 million cases annually (95% CI, 906,000-1,376,000), for sustained habits and 26% (95% CI, 18-34%), or 873,000 cases annually (95% CI, 604,000-1,141,000), for midlife changes.
INTERPRETATION: Higher physical activity and diet quality were associated with substantially reduced chronic disease risk regardless of BMI. These findings support public health strategies that promote healthy behaviors independent of body weight.
FUNDING: US National Institutes of Health, Prevent Cancer Foundation.
PMID:42395933 | PMC:PMC13324697 | DOI:10.1016/j.lana.2026.101540