Men who were thin during early adulthood exhibited greater weight gain‐associated visceral fat accumulation in a study of middle‐aged Japanese men

OBJECTIVE: This study aimed to assess the relationship between weight gain from early adulthood and visceral fat accumulation. METHODS: The participants were 549 men aged 42 to 64 years who were randomly selected from the local resident registry for the National Institute for Longevity Sciences' neighbourhood. They were asked to recall their weight at 18 years of age, and then, post‐18 weight‐change values were calculated for each participant (their current weight minus their weight at 18). The participants were divided according to their median body mass index (BMI) at 18 years of age (initial BMI) (<20.14 and ≥20.14 kg m(−2)). Visceral fat area (VFA) and subcutaneous fat area (SFA) were measured on computed tomography scans. RESULTS: The participants with initial BMI of <20.14 kg m(−2) exhibited greater post‐18 weight changes than those with initial BMI of ≥20.14 kg m(−2). The participants' post‐18 weight‐change values were negatively correlated with their initial BMI and positively correlated with both VFA and SFA. The slope of the regression line for the relationship between post‐18 weight change and VFA was steeper in the participants with initial BMI of <20.14 kg m(−2) (β = 4.36) than in those with initial BMI of ≥20.14 kg m(−2) (β = 3.23). CONCLUSIONS: Visceral fat accumulation is affected not only by an individual's post‐18 weight gain but also by their initial BMI. Men who were thin in early adulthood experienced greater weight gain‐associated VFA increases, but the same was not true for SFA.