How GLP-1 Drugs Affect Appetite, Stomach Emptying, and Food Preferences: A Systematic Review | Research

The takeaway

A systematic review of 12 RCTs found that GLP-1 analogs suppress appetite, slow stomach emptying, and alter food preferences and taste in adults with obesity.

12 RCTs, 445 participants
Systematic review evidence showing GLP-1 analogs affect multiple appetite and eating behavior parameters simultaneously

What the researchers found

Across 12 randomized controlled trials involving 445 participants, GLP-1 analogs consistently demonstrated effects on multiple appetite-related parameters:

- **Appetite suppression**: Most studies showed reduced hunger and increased fullness

- **Delayed gastric emptying**: Food stayed in the stomach longer, prolonging satiety

- **Food preference changes**: Shifts away from high-fat and high-calorie foods

- **Taste alterations**: Changes in taste sensitivity and perception

The review found that GLP-1 drugs work through these multiple, complementary mechanisms rather than a single pathway — helping explain their superior weight loss efficacy compared to earlier anti-obesity medications that typically targeted only one mechanism.

Why it matters

Understanding how GLP-1 drugs change eating behavior goes beyond academic interest — it has practical implications for patient counseling and treatment optimization. Knowing that these drugs alter food preferences and taste can help doctors prepare patients for what to expect. It also explains why patients on GLP-1 drugs often report that their relationship with food fundamentally changes, not just that they eat less. This multi-mechanism approach may be key to the long-term weight management success of these drugs.

How the study worked

The researchers conducted a systematic literature search across PubMed, Scopus, and ScienceDirect from October to December 2021. Only randomized controlled trials were included. Studies had to test GLP-1 analogs of any dosage and duration in adults with obesity without other chronic diseases, measuring appetite, gastric emptying, food preferences, or taste as outcomes. Risk of bias was assessed using the Cochrane RoB2 tool. Twelve studies met the inclusion criteria.

What this study cannot tell us

The review included only 12 studies with a combined 445 participants — a relatively small evidence base. The literature search ended in December 2021, missing more recent studies including large semaglutide and tirzepatide trials. Studies varied in which GLP-1 analog was used, dosage, and duration, making direct comparisons difficult. Longer-term studies are needed to determine whether these appetite and taste effects persist over time or if tolerance develops.

How to read the evidence

This is a systematic review of randomized controlled trials, representing a high level of evidence synthesis. However, the small number of included studies (12) and total participants (445) limit the strength of conclusions. The review methodology was rigorous, using Cochrane risk-of-bias assessment.

When this study was published

Published in 2023 with a literature search ending in 2021, this review captures the evidence base before the most recent large semaglutide and tirzepatide trials. The core findings about appetite mechanisms remain relevant, though newer data would strengthen the conclusions.

The bigger picture

The finding that GLP-1 drugs affect food preferences and taste perception — not just hunger — helps explain the anecdotal reports from patients who say they lose interest in foods they previously craved. This connects to emerging research on how GLP-1 receptors in the brain influence reward processing, potentially explaining why these drugs also seem to reduce interest in alcohol and other addictive behaviors. The multi-mechanism approach also sets GLP-1 drugs apart from earlier anti-obesity medications that typically only suppressed appetite without changing food preferences.

Questions still open

Do the changes in food preferences and taste persist after stopping GLP-1 drugs, or do they revert?
Which specific brain GLP-1 receptor pathways mediate the changes in food preferences versus the changes in hunger?
Are the taste and food preference effects dose-dependent, or do they occur even at lower doses?

Common questions

How do GLP-1 drugs change your appetite?

GLP-1 drugs work on multiple levels: they signal the brain to reduce hunger, slow down stomach emptying so food stays in your stomach longer, and actually change what foods you find appealing and how they taste. This combination means patients don't just eat less — many report that they genuinely lose interest in foods they used to crave, especially high-fat and high-calorie options.

Do GLP-1 drugs change how food tastes?

Yes — this review found evidence that GLP-1 drugs alter taste sensitivity and perception. Some patients report that foods taste different or less appealing than before treatment. The exact mechanism isn't fully understood, but GLP-1 receptors are found in taste-processing areas of the brain, which may explain how these drugs can change the sensory experience of eating.

Read the original research

The Efficacy of GLP-1 Analogues on Appetite Parameters, Gastric Emptying, Food Preference and Taste Among Adults with Obesity: Systematic Review of Randomized Controlled Trials.

Diabetes, metabolic syndrome and obesity : targets and therapy, 16, 575-595

View on PubMed ↗Publisher’s paper ↗

Citation

Aldawsari, Malikah; Almadani, Fatima A; Almuhammadi, Nujud; Algabsani, Sarah; Alamro, Yara; Aldhwayan, Madhawi. (2023). The Efficacy of GLP-1 Analogues on Appetite Parameters, Gastric Emptying, Food Preference and Taste Among Adults with Obesity: Systematic Review of Randomized Controlled Trials.. Diabetes, metabolic syndrome and obesity : targets and therapy, 16, 575-595. https://doi.org/10.2147/DMSO.S387116