S Tonstad, N Malik, E. Haddad
High-fibre and low-carbohydrate diets may enhance satiety and promote weight loss. We compared a diet rich in beans aiming to increase dietary fibre and promote weight loss with a low-carbohydrate diet in a randomised controlled trial to assess effect and tolerability of the high-fibre bean-rich diet.
Methods and results
One hundred and seventy-three women and men, with a mean body mass index of approximately 36 kg m−2 (one-fifth with diabetes type 2) were randomised to a high-fibre bean-rich diet that achieved mean (SD) fibre intakes of 35.5 (18.6) g day−1 for women and 42.5 (30.3) g day−1 for men, or a low-carbohydrate diet. Both diets were induced gradually over 4 weeks and included a 3-day feeding phase. Among 123 (71.1%) completers at 16 weeks, mean (SD) weight loss was 4.1 (4.0) kg in the high-fibre versus 5.2 (4.5) kg in the low-carbohydrate group [difference, 1.1 kg, 95% confidence interval (CI) = −2.6 to −0.5; P = 0.2], with results similar to the intent-to-treat population. Low-density lipoprotein (LDL)-cholesterol levels decreased with the high-fibre diet (difference in LDL-cholesterol versus low-carbohydrate diet, 0.2 mmol L−1, 95% CI = 0.01–0.44 mmol L−1; P = 0.045), as did total cholesterol (P = 0.038), whereas changes in other lipids and glucose did not differ. After 52 weeks, the low-carbohydrate (n = 24) group tended to retain weight loss better than the high-fibre group (P = 0.06), although total cholesterol remained lower with the bean-rich diet (P = 0.049).
A high-fibre bean-rich diet was as effective as a low-carbohydrate diet for weight loss, although only the bean-rich diet lowered atherogenic lipids.