Objective: To examine the relationship between waist circumference and cardiovascular risk factors during weight loss, and to consider possible waist reduction targets for weight management.
Design: Single strand six month weight loss study on food based diets in 110 women aged 18-68 y, and body mass index > or = 25 kg/m2 set at an outpatient clinic.
Main outcome measures: Waist circumference, weight, body mass index (BMI), total plasma cholesterol, low (LDL) and high density lipoprotein (HDL) cholesterol, triglyceride, and blood pressure.
Results: Anthropometric and metabolic measurements improved with mean weight loss of 4.9 (s.e.m. +/- 0.4) kg at three months and 6.2 (s.e.m. +/- 0.4) kg at six months. Weight loss closely related to waist reduction (% Weight loss = 0.85 x Waist reduction (cm)-2.09; r = 0.79). The proportion of subjects with waist circumference below Action Level 1 (< 80 cm) or above Action Level 2 (> or = 88 cm) were 9 and 60% at baseline, 29 and 38% at three months and 36 and 33% at six months. Waist reduction (adjusted for age, smoking, alcohol consumption, diet treatment and baseline dependent and independent variables) correlated significantly with falls in total cholesterol (r = 0.31; P < 0.01), LDL cholesterol (r = 0.35; P < 0.01) and diastolic blood pressure (r = 0.32; P < 0.01), but not significantly with HDL cholesterol, triglyceride or systolic blood pressure. BMI showed similar correlations, whereas waist to hip ratio changes were not associated with changes in any cardiovascular risk factors. Amongst those whose waist fell by > or = 5 cm, 45 at three months and 43 at six months, there were > or = 10% improvements in at least one risk factor for 71 and 84% respectively. Amongst those whose waist fell by 5-10 cm, 40 women at three months and 30 at six months, at least one risk factor improved by > or = 10% in 70% and in 83% respectively.
Conclusions: Waist reduction of 5-10 cm in Caucasian women, across a range of baseline BMI 25-50 kg/m2 or waist circumference 72-133 cm, may be used as guideline to encourage overweight women to achieve a realistic target with a high probability of health benefits.