Short-term weight gain is associated with accumulation of multimorbidity in mid-aged women: a 20-year cohort study.

BACKGROUND/OBJECTIVES: Although weight change has been studied in relation to many individual chronic conditions, limited studies have focused on weight change and multimorbidity. This study examines the relationship between short-term weight change and the accumulation of multimorbidity in midlife. METHODS: We used data from 7357 women aged 45-50 years without a history of any chronic conditions. The women were surveyed approximately every 3 years from 1996 to 2016. Associations between short-term weight change and accumulation of multimorbidity (two or more of nine chronic conditions) over each 3-year period, adjusting for baseline body mass index (BMI) or time-varying BMI (3-year period), were examined using repeated measures models. Short-term weight change was categorised into seven groups of annual weight change from high weight loss ( ≤ -5%) to high weight gain (> + 5%). RESULTS: Over 20 years, 60.4% (n = 4442) of women developed multimorbidity. Baseline BMI, time-varying BMI and short-term weight gain were all associated with the accumulation of multimorbidity. After controlling for sociodemographic, lifestyle factors and menopausal status, high weight gain was associated with a 25% increased odds of multimorbidity (odds ratio (OR) 1.25, 95% confidence interval (CI) 1.08-1.45) compared with maintaining a stable weight. The results were consistent among models adjusting for baseline BMI (OR 1.24, 95% CI 1.07-1.44) or time-varying BMI (OR 1.34, 95% CI 1.16-1.54). Weight loss was associated with increased odds of multimorbidity in women with normal BMI (baseline or time-varying). CONCLUSIONS: Short-term weight gain is associated with significantly increased odds of multimorbidity in mid-aged women. This association is independent from baseline BMI (at 45-50 years) and time-varying BMI. These findings support a persistent weight management regime and prevention of weight gain throughout women's midlife.