Motivational effects of 12-week moderately restrictive diets with or without special attention to the Glycaemic Index of foods

Low glycaemic index (GI) diets may facilitate weight loss via behavioural and/or endocrine mechanisms. This study investigated whether the outcomes of the Weight Watchers POINTS® Weight-Loss System could be improved by encouraging dieters to select low GI, high-carbohydrate foods. Ninety-six women (age 20–72 years; BMI 25–40 kg/m2) were recruited as they started the Weight Watchers POINTS® programme for 12 weeks. Weekly classes were randomized so that seven (forty-five women) followed the regular programme while seven others (fifty-one women) followed a revised programme encouraging the selection of low GI foods. Anthropometric and biochemical parameters were measured before and after the 12-week diets. Participants rated hunger and desire to eat using visual analogue scales on 1 d per week, several times per d. Attrition was the same in both groups (32 v. 30 %), as well as many benefits (5 % weight loss, decreases in insulinaemia and blood lipids, waist and hip circumferences, blood pressure). Hunger and desire to eat were rated consistently lower in the low GI group over the 12-week diet. Group differences in subjective sensations were especially large in the afternoon. The 12-week weight management yielded many significant anthropometric and biochemical benefits that were not improved by encouraging dieters to select low GI foods. The subjective benefits (lower hunger and desire to eat) of the low GI diet may be a worthwhile contribution to the motivation of dieters that might affect adherence to the diet over the long term.