There was no significant difference in weight change between a healthy low-fat (HLF) diet vs a healthy low-carbohydrate (HLC) diet in overweight adults, and neither genotype pattern nor baseline insulin secretion was associated with the dietary effects on weight loss. This according to results from the DIETFITS randomized clinical trial that included 609 adults aged 18 to 50 years without diabetes with a body mass index (BMI) between 28 and 40. Participants were randomized to the 12-month HLF or HLC diet. The primary outcome was a 12-month weight change and determination of whether there were significant interactions among diet type and genotype pattern, diet and insulin secretion, and diet and weight loss. Researchers found:

• 481 of 609 randomized participants completed the trial.
• Weight change over 12 months was not significantly different for participants in the HLF diet group (−5.3 kg) vs the HLC diet group (−6.0 kg).
• There was no significant diet-genotype interaction or diet-insulin interaction with 12-month weight loss.
• There were 18 adverse events or serious adverse events that were evenly distributed across the 2 diet groups.