GLP-1 medications roughly double the risk of gallstones compared to placebo in clinical trials, largely because rapid weight loss itself is a known gallstone risk factor, with some additional contribution from the drug's direct effect on gallbladder motility.

Roughly 25 to 40 percent of weight lost on GLP-1 medications can come from lean mass rather than fat, according to published research, though estimates vary widely by study. Adequate protein intake and resistance exercise are the most consistently supported ways to reduce this.

Diarrhea affects roughly 30-33% of GLP-1 patients. Research suggests longer-acting GLP-1 medications tend to cause more diarrhea, while shorter-acting ones lean more toward nausea and vomiting.

Nausea is the most common side effect of GLP-1 medications, affecting roughly 40-70% of patients, most often during dose escalation. It happens because these medications slow stomach emptying and act on nausea-related receptors in the brain.

Gastroparesis means the stomach empties too slowly. Slowed gastric emptying is part of how GLP-1 medications are designed to work, but in rare cases the effect becomes severe or persists after stopping the medication. The FDA added gastroparesis and ileus warnings to GLP-1 labeling in 2023.

Hair loss on GLP-1 medications is usually telogen effluvium, a temporary shedding pattern triggered by rapid weight loss and nutritional shifts, not a direct drug effect on hair follicles. It typically resolves within 3 to 6 months once weight stabilizes.

Vomiting is a common but less frequent GLP-1 side effect than nausea, and typically follows the same dose-escalation pattern. Persistent vomiting is more likely than other GI symptoms to warrant a dose adjustment.

Dehydration is usually a downstream effect of GI side effects like vomiting and diarrhea, not a direct drug effect. In rare cases, severe or prolonged dehydration on a GLP-1 medication has been linked to acute kidney injury, which is why staying ahead of fluid losses matters.

Fatigue on GLP-1 medications is usually linked to reduced calorie intake, dehydration from GI side effects, or the body adjusting to rapid weight loss, not a direct drug effect on energy itself.

Constipation affects roughly 24-30% of GLP-1 patients and results from the same slowed digestion that drives the medication's appetite-suppressing effect. It's manageable with fiber, water, and movement in most cases.