Effects of a low glycemic load diet versus a low-fat diet in subjects with and without the metabolic syndrome

Background and aimAlthough many studies report benefits of low glycemic diets, the clinical effects as a whole are mixed. The study aim was to compare a low glycemic load (LGL) diet versus a low-fat diet in a trial with a moderately intense dietary intervention in subjects with varying degrees of metabolic syndrome.Methods and resultsMen and women aged 30–65 years, with a BMI of 28–40 kg/m² (28–35 for women) and at least one criterion of metabolic syndrome were randomized to the two diets. A total of 202 subjects were included, of which 126 (62%) had metabolic syndrome (≥3 criteria). The completion rate was 81%. At 3 months, weight loss was greater in the LGL group (?4.8 ± 3.9 kg versus ?3.8 ± 3.5 kg; P = 0.06) compared to the low-fat group. At 1 year, however, weight loss was similar in both groups (?4.0 ± 5.5 kg versus ?4.3 ± 6.2 kg; n.s.), but waist circumference reduction was less in the LGL group (?3.9 ± 5.3 cm versus ?5.8 ± 6.8 cm; P = 0.03). In contrast, diastolic blood pressure decreased significantly more in the LGL group (?4.0 ± 8.7 mmHg versus ?1.1 ± 8.5 mmHg; P = 0.02). We also observed a significant interaction between the presence of the metabolic syndrome and the effect of the two diets on waist circumference, with a less favorable effect of the LGL diet in subjects without the syndrome (P = 0.039).ConclusionAfter 12 months, both diets reduced body weight and the metabolic disturbances similarly, but the LGL diet appeared more suitable for subjects with metabolic syndrome, and was less effective in those without it.