Plant-based dietary patterns are associated with lower body weight, BMI and waist circumference in older Australian women

OBJECTIVE: To investigate the association between plant-based diets (PBD) and overweight/obesity compared to regular meat eaters in older women. DESIGN: Cross-sectional analysis. SETTING: 1946–1951 birth cohort of the Australian Longitudinal Study on Women’s Health (ALSWH). PBD were categorised as vegan, lacto-ovo vegetarian, pesco-vegetarian, semi-vegetarian and regular meat eaters. Outcomes included body weight (BW), BMI and waist circumference (WC). PARTICIPANTS: Women who completed Survey 7 (n 9102) with complete FFQ data. RESULTS: Compared to regular meat eaters, BW, BMI and WC were significantly lower in pesco-vegetarians (−10·2 kg (95 % CI −5·1, −15·2); −3·8 kg/m(2) (95 % CI −2·0, −5·6); −8·4 cm (95 % CI −3·9, −12·9)) and BW and BMI lower in lacto-ovo vegetarians (−7·4 kg (95 % CI −1·2, −13·6); −2·9 kg/m(2) (95 % CI −0·6, −5·1)). In regular meat eaters, individuals consuming meat daily or multiple times/d had significantly higher BW, BMI and WC compared to those consuming meat >2 times/week but <daily or multiple times/d (2·5 kg (95 % CI 1·5, 3·5); 0·9 kg/m(2) (95 % CI 0·5, 1·3) and 2·2 cm (95 % CI 1·3, 3·1)) and those consuming meat >1 but ≤2 times/week (6·8 kg (95 % CI 1·8, 11·8); 2·1 kg/m(2) (95 % CI 0·3, 4·0) and 6·0 cm (95 % CI 1·7, 10·4)). This association was dose-dependent such that for every increase in category of weekly meat intake (i.e. >1 time/week but ≤2 times/week; >2 times/week but less than daily, and daily or multiple times/d), an associated 2·6 kg (95 % CI 1·8, 3·4) increase in BW, 0·9 kg/m(2) (95 % CI 0·6, 1·2) increase in BMI and 2·3 cm (95 % CI 1·6, 3·0) increase in WC was reported. CONCLUSIONS: BW, BMI and WC are lower in women following PBD and positively associated with increasing meat consumption. Results were robust to adjustment for confounders including physical activity levels, smoking status, habitual alcohol intake, use of supplements, and hormone replacement therapy.