OBJECTIVES: To study how body mass index (BMI, kg/m2) at 14 and 31 years (y) changes in BMI between 14 and 31 y, and waist-to-hip ratio (WHR) at 31 y are associated with poor perceived working ability at 31 y. DESIGN AND SUBJECTS: A population-based cohort, originally 11637 people, born in Northern Finland in 1966 was resurveyed at 14 and 31 y. MEASUREMENTS: Perceived work ability (measured by modified work ability index, WAI), BMI, WHR, alcohol intake, smoking, basic education and work history were recorded at 31 y and BMI also at 14 y. RESULTS: Low WAI (15% of lowest values) at 31 y showed a U-shaped association with BMI at 14 y, and also with BMI at 31 y, except in obese males. Low WAI similarly had a U-shaped association with WHR, but in males only, while in females, the probability of low WAI increased almost linearly with WHR. Low WAI was more common among smokers and people with a low level of education. The pattern for alcohol intake was more equivocal, with a nonsignificant finding in males and an almost linear decrease of low WAI with increasing alcohol intake in females. CONCLUSIONS: Work ability, health habits and anthropometric measures should be evaluated regularly in young workers, and preventive measures against diseases leading to premature retirement should be taken in time, for example by the occupational health-care service.