Summary: This systematic review examined the impact of low glycaemic index or load (GI/GL) diets on weight loss in overweight or obese individuals, analyzing data from 10 randomized controlled trials (RCTs), with 1,210 participants. The main outcomes included changes in body weight, body mass index (BMI), adverse events, health-related quality of life, and mortality. The study showed that low GI/GL diets probably result in little to no difference in body weight and BMI changes compared to higher GI/GL diets or other diets. The evidence suggests a lack of effect on all main outcomes and the possible positive influence on mood remains uncertain.
The studies included in this review had a small sample size with a moderate to very low certainty of evidence. This suggests more well-structured studies with larger sample sizes are needed for firmer conclusions. Limitations of this review included the risk of bias, as many of the studies did not adopt objective outcome measurements and some had a high degree of loss to follow-up. Furthermore, the researchers recommend that future studies focus on diverse demographic groups and include participants from low- and middle-income countries.