GLP 1 receptor agonists are widely prescribed for weight loss and glycaemic control, yet a new systematic review reveals that dietary intake and diet quality are rarely assessed in randomised controlled trials evaluating these agents.
GLP 1 Receptor Agonists and Dietary Outcomes
With increasing clinical use of glucagon like peptide one and glucose dependent insulinotropic polypeptide receptor agonists, understanding their impact on dietary behaviour is increasingly relevant. This systematic review examined how randomised controlled trials prescribing liraglutide, semaglutide, or tirzepatide assessed and reported dietary intake and diet quality alongside weight loss and or glycaemic control outcomes.
Databases including Medline, Embase, Cochrane, Scopus, and CINAHL were searched from January 2008 to January 2025 for adult populations and from January 2014 to January 2025 for children and adolescents. In total, 43 articles from 41 unique randomised controlled trials were included, comprising 50,690 participants. Of these, 688 were children or adolescents and 50,002 were adults.
Limited Reporting of Dietary Intake
Only two studies, both conducted in adults, assessed or reported dietary intake or changes in diet. One of these studies was published, while the other included unpublished data from an included trial. Both reported reductions in total energy intake and alterations in macronutrient distribution in groups receiving medication plus diet. However, in one study, changes were not significantly different compared with medication alone.
The methodological quality of dietary assessment in the two studies was categorised as poor and acceptable, respectively. No additional trials evaluated diet changes secondary to glucagon like peptide one or glucose dependent insulinotropic polypeptide receptor agonist use.
Overall, just two of 41 trials, approximately 5%, incorporated dietary intake as an outcome measure.
Need for High Quality Research
These findings highlight a substantial gap in the evidence base with regard to how glucagon like peptide one receptor agonists influence diet quality, nutrient intake, and chronic disease risk. Despite large scale enrolment across trials, dietary outcomes remain largely unexamined.
The authors conclude that more high-quality research using validated dietary assessment methods as outcome measures in randomised controlled trials is urgently needed to clarify the nutritional implications of glucagon like peptide one and glucose dependent insulinotropic polypeptide receptor agonist therapy.
Reference
Jansson AK et al. A systematic review identifying critical evidence gaps in reporting dietary change in randomized controlled trials prescribing liraglutide, semaglutide, or tirzepatide. Obes Rev. 2026:e70077.
