Wholegrain rye, but not wholegrain wheat, lowers body weight and fat mass compared with refined wheat: a 6-week randomized study

Abstract

Observational studies suggest inverse associations between wholegrain intake and body weight gain. Only few controlled intervention studies have supported this association and few compare effects of different grain varieties. To investigate how wholegrain wheat (WGW) and rye compared with refined wheat (RW) affect body weight and composition and appetite sensation. Seventy overweight/obese adults participated in this 6-week randomized parallel study, in which they replaced their habitual cereal foods with RW, WGW or wholegrain rye (WGR). Further, a 4 h postprandial test meal challenge was completed with meals corresponding to diet allocation in the beginning and after the intervention. Body weight and composition, fasted blood samples, compliance and 4-day dietary intake were obtained before and after the intervention period. Appetite and breath hydrogen excretion was assessed during the postprandial test meal challenge. Diet allocation affected body weight significantly (P=0.013) and tended also to affect fat mass (P=0.065). Both body weight and fat mass decreased more in the WGR group (-1.06±1.60 and -0.75±1.29 kg, respectively) compared with the RW group (+0.15±1.28 and -0.04±0.82 kg, respectively; P<0.01 and P<0.05, respectively). Further, the decrease in fat mass in the WGR group tended to exceed that in the WGW group (P=0.07). Overall, no effect of diet on appetite sensation was observed; however, energy intake from study products was ~200 kcal lower in the WGR group when compared with that in the RW group (P<0.05), although total energy intake did not differ between groups. Our results support a role for WGR foods in body weight regulation, when provided ad libitum. The effect may be mediated by satiation reflected in a reduction in energy intake, mainly from the wholegrain products without compensation in other parts of the diets, despite no difference in appetite.