Objective: To examine how thinness is associated with indicators of socio-economic disadvantage, health-related behaviours, and health indicators including mortality.
Design: Independent risk factor surveys carried out in four geographic areas in Finland in 1982, 1987, 1992, and 1997, with mortality follow-up to the end of the year 2001.
Subjects: A total of 13 389 men and 14 770 women aged 25-64 y at baseline, and 2077 deaths during the follow-up when subjects who have died during the first 5 y were excluded.
Methods: A self-administrative questionnaire data on socio-economic status, health behaviour, and perceived health, together with measured height, weight, and metabolic indicators using standardised protocol. Mortality data by Statistics Finland were linked to the baseline surveys.
Results: Thin men (BMI</=20 kg/m(2)) were the socio-economically disadvantaged group engaged in adverse health behaviours. They also reported poorer perceived health despite having better metabolic indicators. Thin women reported more adverse behaviours than other women and had better metabolic profile than their obese counterparts. Thin subjects had higher mortality, but results become nonsignificant among men when first 5 y of follow-up were excluded, and nonsignificant among women when health behaviours were adjusted for.
Conclusion: Thinness is associated with good metabolic profile but increased mortality, explained partly by underlying diseases or adverse behaviours. Thinness in men is associated with socio-economic disadvantage.