Desire for thinness among young Japanese women from the perspective of objective and subjective ideal body shape.

I examined the actual situation of the desire to be thin among young Japanese women from the perspective of ideal body shape and actual measured body shape. In total, 90 young Japanese women were evaluated using a questionnaire (perceived body shape and desired body composition change) and assessments of sarcopenia (muscle strength, physical ability, and muscle mass). Participants were classified into the underweight (body mass index [BMI] < 18.5 kg/m, 74%), normal-weight (18.5 ≤ BMI < 25 kg/m, 20%), or obese (25 ≤ BMI < 30 kg/m, 6%) groups. The normal-weight group needed to gain an average of 2.2 kg to reach the objective ideal weight, but participants desired to lose an average of 4.5 kg. The underweight group needed to gain an average of 10.3 kg to reach the objective ideal weight, but participants desired to maintain their current body weight. Data on muscle mass for the diagnosis of sarcopenia showed low values for the underweight group. Most participants were classified into the normal-weight and underweight groups, but these groups showed a high percentage of women with a desire to be thin. The body shape of young adult women should be carefully considered not only as a health issue of thinness during the fertile period but also as a countermeasure to sarcopenia (low skeletal muscle mass) during the aging process.