BACKGROUND: Weight gain in perimenopausal women results in increased visceral adipose tissue, leading to metabolic syndrome and associated comorbidities. Despite a high prevalence of weight gain at this life stage, interventions to prevent menopausal obesity are lacking. AIM: To test the effectiveness of an intervention delivered by health professionals using a motivational interviewing (MI) counselling style in preventing weight gain in non-obese (body mass index (BMI) 18.5 and 29.9 kgm -2) women in late premenopause. METHODS: In a randomised controlled trial, 54 women (mean (s.d.) age 47.3 (1.8) years; BMI 25.1 (2.4) kgm -2) who had menstruated within the preceding 3 months were randomly assigned to an MI intervention (n=28) (five health professional MI counselling sessions) or a self-directed intervention (SDI) (print materials only) (n=26). The primary outcome, body weight (kg) and secondary outcomes (blood lipids, glucose, body fat %, lean mass % and waist circumference) were measured at baseline and postintervention (12 months), and intention-to-treat analysis was conducted. RESULTS: Forty women completed all measures and adhered to all protocols. The weight at 12 months for the MI group of 65.6 kg (95% CI: 64.5; 66.8) was significantly different (P=0.034) from the SDI group of 67.4 kg (95% CI: 66.2; 68.6). When stratified by baseline BMI category, the MI group lost significantly more weight (-2.6 kg; 95% CI: -3.9; -1.2) than the SDI group (-0.1 kg; 95% CI: -1.2; 1.0, P=0.002) for the healthy weight women. The overweight women lost weight regardless of the intervention group, with no between-group difference (-3.5 kg; 95% CI: -6.1, -1.0 and -2.3; 95% CI: -4.1, -0.5, P=0.467). CONCLUSION: This relatively low-intensity intervention, incorporating MI into health professional counselling, not only effectively prevented weight gain but also achieved significant weight loss and decreased diastolic blood pressure. Further refinements are required to optimise outcomes for overweight women.