IntroductionThis study examines the background of underweight young women in Japan from multiple perspectives, focusing on whether they have ever dieted.MethodsA screening survey was administered to 5,905 underweight (BMI < 18.5 kg/m2) women aged 18–29 years, who could report their birth weight recorded in their mother-child handbook. Valid responses were obtained from 400 underweight and 189 normal-weight women. The survey collected data regarding height, weight (BMI), body image and perception of weight, dieting experience, exercise habits from elementary school age onwards, and current eating habits. Additionally, five standardized questionnaires were used (EAT-26, eHEALTH, SATAQ-3 JS, TIPI-J, and RSES). The primary analysis was a comparative analysis (t-test/χ2)—with the presence or absence of underweight and diet experience as independent variables, and each questionnaire as a dependent variable.ResultsThe screening survey revealed that approximately 24% of the total population was underweight, with a low mean BMI. Of the respondents, more than half reported their body image as skinny and a small percentage as obese. Compared with the non-diet-experienced group (NDG), the diet-experienced group (DG) had a significantly higher proportion of past to current exercise habits. There was a significantly higher percentage of disagreement responses from the DG for weight and food gain than for the NDG. The NDG weighed significantly less than the DG in terms of birth weight, and lost weight easier than the DG. Additionally, the NDG was significantly more likely to agree with increasing weight and food intake. The NDG’s exercise habits were below 40% from elementary school age to the present, predominantly owing to a dislike for exercise and a lack of opportunity to implement it. In the standardized questionnaire, the DG was significantly higher for EAT-26, eHEALTH, SATAQ-3 JS, and Conscientiousness (TIPI-J), whereas the NDG was only significantly higher for Openness (TIPI-J).DiscussionThe results suggest the need for different health education programs for underweight women who desire to lose weight and experience dieting and for those who do not. This study’s results are reflected in the development of sports opportunities optimized for each individual, and in the development of measures to ensure adequate nutritional intake.

Abstract. Physical activity helps to prevent the development of chronic non-communicable diseases. However, childbearing generally reduces parents' level of physical activity, particularly in mothers. Therefore, mothers with young children generally have lower levels of physical activity and have a higher risk of developing non-communicable diseases. The aim of the present study was to examine this risk in Japanese working mothers with young children. A cross-sectional study was conducted in four nursery schools in Nagano city, Japan. All mothers were asked to complete a questionnaire regarding abnormal findings at their proximate annual medical examination, and were asked to record their normal physical activity. A total of 182 mothers completed the questionnaires, and 36 reported having abnormal findings (ABN group). Mothers in the ABN group were significantly older than those without abnormal findings (NOR; P=0.043). No significant differences in physical activity were observed between the two groups; however, mothers in the ABN group spent a significantly longer time sitting than those in the NOR group (P= 0.028). Regarding socioeconomic characteristics, mothers in the ABN group had a significantly higher educational background (P= 0.040) and a higher annual family income (P<0.001) compared with those in the NOR group, and significantly more mothers held full-time jobs (55.9 vs. 36.0%; P= 0.005). Full-time working mothers typically had a significantly higher family income (P<0.001) and spent a significantly longer time sitting (P<0.001) compared with mothers in part-time and other work. Therefore, the results of the present study suggest that sedentary lifestyles, namely the amount of time spent sitting, may increase the risk of Japanese working mothers with young children developing non-communicable diseases.