出口 香菜子

Background: Underweight status is common among young women in Japan and has been linked to impaired glucose tolerance, but its long-term association with HbA1c trajectories remains unclear. This study examined whether body size history in the twenties is associated with subsequent HbA1c trajectories across adulthood. Methods: We analyzed health check-up data from Fujita Health University, collected between 2003 and 2025. Participants were classified as normal weight in the twenties (NW20s), underweight at least once in the twenties (UW20s_ever), or overweight at least once in the twenties (OW20s_ever), excluding mixed underweight/overweight histories. Eligible individuals had at least 5 years of follow-up, at least five BMI and HbA1c measurements, and at least one BMI record between ages 20 and 29 years. HbA1c trajectories were evaluated using sex-stratified linear mixed-effects models. Kaplan-Meier and Cox regression analyses were used to assess the risk of first reaching HbA1c ≥ 5.6%. Results: A total of 2923 participants were included in the trajectory analysis. For the time-to-event analysis, 2753 participants were included after exclusion of 170 participants with HbA1c ≥ 5.6% at study entry. Body size history in the twenties was associated with distinct, sex-specific HbA1c trajectories. OW20s_ever showed persistently higher HbA1c levels in both women and men, but the local slope of HbA1c was greater at ages 35 and 45 years in women and at age 25 years in men. In contrast, UW20s_ever showed lower HbA1c levels than NW20s at ages 25 and 35 years only in women. In complementary time-to-event analyses, OW20s_ever was associated with a higher risk of HbA1c ≥ 5.6% in both women and men (women: HR 1.37, 95% CI 1.06-1.76, p = 0.016; men: HR 1.81, 95% CI 1.41-2.32, p < 0.001), whereas UW20s_ever was associated with a lower risk only in women (HR 0.81, 95% CI 0.67-0.98, p = 0.028). Conclusions: Underweight and overweight history in the twenties are not simply mirror-image exposures but rather have sex-dependent and asymmetric associations with later HbA1c regulation.

BACKGROUND: Underweight (BMI < 18.5 kg/m2) remains prevalent among young Japanese women but lacks standardized measurement approaches. We compared four analytical methods and identified discrepancies. METHODS: A retrospective analysis of 883 underweight women aged 20-29 years followed for 6.1 ± 4.2 years was performed. We compared (1) year-to-year transitions, (2) state occupancy, (3) the Aalen-Johansen estimator, and (4) Kaplan-Meier Survival Analysis. We performed bidirectional flow analysis quantifying inflow/outflow rates, BMI distribution analysis, and time-weighted classification. RESULTS: Methods 1 and 4 showed 31-point discrepancies (78.1% vs. 47.1% in women). In bidirectional flow, inflow exceeded outflow at ages 22-27 (35.7%/yr vs. 20.7%/yr, outflow/inflow ratio: 0.58), balanced at ages 27-37 (ratio: 1.02) and showed outflow-dominant pattern at ages 37-47 (ratio: 4.92). BMI clustered at 18.0-19.0 kg/m2 (42.7%); 69.4% crossed the threshold once. Time-weighted classification revealed four phenotypes: persistent (≥75% time underweight; 40.1%, BMI: 17.54 kg/m2), moderate (50-74%; 17.6%, BMI: 18.40 kg/m2), intermittent (25-49%; 17.6%, BMI: 18.97 kg/m2), and transient (<25%; 24.8%, BMI: 19.49 kg/m2). The moderate + intermittent group showed yo-yo phenotypes (35.2%). CONCLUSIONS: Underweight in young Japanese women should be viewed as a heterogeneous dynamic nutritional state. The methodological discrepancy, threshold crossing, and phenotypic classification show that BMI-defined underweight comprises distinct patterns. Cross-sectional data evaluation may lead to incorrect assessments. Future research examining relationships between longitudinal low body weight subgroups and clinical outcomes could identify at-risk populations within the underweight group.

Background: Medical nutrition therapy (MNT) is crucial for diabetes management. This study evaluated a hands-on nutrition education program that incorporated cooking demonstrations for glycemic control, anthropometrics, and dietary behavior over a 2-month period. Methods: Nineteen type 2 diabetes patients (four males and 15 females; 79% female) participated. The median [IQR] age was 70.0 [65.5–73.0] years; the duration of diabetes was 12.0 [8.5–14.0] years; the body mass index (BMI) was 24.3 [21.05–27.90] kg/m2, and the baseline HbA1c level was 6.90 [6.55–7.50%]. Approximately 20–25% of patients used injectable therapies. Pre- and post-treatment comparisons were performed via Wilcoxon signed-rank tests, while effect sizes were quantified via rank–biserial correlation (RBC). Results: In females (n = 15), carbohydrate intake decreased significantly (RBC = −0.583; p = 0.050). The protein levels per 1000 kcal exhibited a strong positive effect (RBC = 0.550; p = 0.065). HbA1c levels improved significantly (overall: RBC = −0.689 and p = 0.009; females: RBC = −0.725 and p = 0.014), and while body fat increased significantly (overall: RBC = 0.979 and p &lt; 0.001; females: RBC = 0.983 and p &lt; 0.001), the skeletal muscle index tended to decrease in females (RBC = −0.333; p = 0.268). Conclusions: Short-term hands-on nutrition education resulted in significant HbA1c improvement and dietary behavior changes but was accompanied by body composition deterioration. The findings of this study clarify the potential risks of nutritional interventions in elderly diabetic patients and provide important insights for improving future programs.

Background: Studies outside Japan have linked sugar-sweetened beverage (SSB) intake with weight gain; however, evidence in Japanese adults is scarce, and no study has examined beverage-derived energy in relation to anthropometric indices and handgrip strength. Methods: The participants were employees of Fujita Health University aged 20-39 years (n = 76; male n = 35, average age: 29.97 ± 4.67 years; female n = 41, average age: 27.29 ± 4.53 years). Energy from beverage intake was assessed via the Brief Beverage Intake Questionnaire-15, and energy from alcoholic drinks, milk, SSBs, and total beverages was calculated. The associations of energy from different beverages with nutrient intake, BMI, skeletal muscle mass index (SMI), and handgrip strength were analyzed via ordinary least squares (OLS) regression; quantile regression (QR) and the generalized additive model (GAM) were used for sensitivity analyses. Results: Increased SSB intake was associated with increased BMI (standardized β = 0.35, 95% CI 0.12-0.58, p(OLS) < 0.001; p(QR) = 0.23; p(GAM) < 0.001) and was nonlinearly associated with increased SMI (standardized β = 0.21, 95% CI 0.043-0.37, p(OLS) = 0.02; p(QR) = 0.11; p(GAM) = 0.02), even after adjustment for total energy intake. Modest milk intake was linked to higher protein intake and a higher SMI without a higher BMI (standardized β = 0.18, 95% CI 0.020-0.35, p(OLS) = 0.03; p(QR) = 0.39; p(GAM) = 0.03). Conclusions: A positive association was found between SSB intake and both BMI and SMI and between MILK intake and SMI. Clarification in larger, diverse Japanese populations will be necessary.