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

BACKGROUND: 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. OBJECTIVE: To investigate how wholegrain wheat (WGW) and rye compared with refined wheat (RW) affect body weight and composition and appetite sensation. DESIGN: 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. RESULTS: 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 similar to 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. CONCLUSIONS: 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.