Desire for underweight among young Japanese women: perspectives on ideal body shape and measured body shape

Abstract We 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 physical fitness and sarcopenia (muscle strength, physical ability, and muscle mass). Participants were classified into the underweight (74%), normal (20%), or obesity (6%) groups. The normal weight group needed to gain 2.2 kg to become ideal, but participants desired a 4.5 kg weight loss (p<0.01). The underweight group needed to gain 10.3 kg to become ideal, but participants desired to maintain their present body weight. There were no differences (p>0.05) among the groups regarding the other physical fitness assessments, except for knee extension strength. Data on muscle mass for the sarcopenia diagnosis showed low values for the underweight group. Most participants were classified as the normal and underweight groups, but these groups showed a high percentage of 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 sarcopenia countermeasure (low skeletal muscle mass) for the ageing period.