GLP-1–based medications have evolved from diabetes drugs into therapies that impact obesity, cardiovascular disease, chronic kidney disease, fatty liver disease (MASH), and obstructive sleep apnea. At the same time, rapid weight loss can have effects on hair and muscle mass, which deserve proactive attention.

This review summarizes the benefits, risks, differences among agents, and supportive strategies, based on peer-reviewed trials and FDA approvals.

Medical Disclaimer

This article is for educational purposes only and does not constitute personal medical advice. Treatment decisions must be individualized and based on physician evaluation, laboratory testing, contraindications, and FDA-approved labeling.

What Are GLP-1 Medications?

GLP-1 (glucagon-like peptide-1) receptor agonists mimic a naturally occurring gut hormone that regulates:

• Appetite and satiety
• Gastric emptying
• Insulin and glucagon secretion
• Cardiometabolic pathways beyond glucose control (1)

Some newer medications (like tirzepatide) act on both GLP-1 and GIP receptors, producing a dual-incretin effect (2).

• Weight Loss and Obesity Treatment

Semaglutide

In the STEP-1 trial, adults with obesity receiving semaglutide 2.4 mg weekly lost 14.9% of body weight on average, compared with 2.4% in the placebo group (3).

Tirzepatide

In SURMOUNT-1, tirzepatide produced mean weight reductions of 15.0% (5 mg), 19.5% (10 mg), and 20.9% (15 mg) vs 3.1% with placebo (2).

Type 2 Diabetes

GLP-1 receptor agonists lower A1c while promoting weight loss and have lower intrinsic hypoglycemia risk when not used with insulin or sulfonylureas. They are recommended in modern ADA guidelines for patients needing glycemic control with cardiovascular or weight benefit (4).

Cardiovascular Risk Reduction

GLP-1 therapies have demonstrated reductions in major adverse cardiovascular events (MACE):

• Semaglutide (SELECT trial) reduced cardiovascular death, MI, and stroke in people with obesity and established CVD (5).
• Liraglutide (LEADER) reduced cardiovascular death and all-cause mortality in T2D (6).
• Dulaglutide (REWIND) showed MACE reduction even in lower-risk T2D populations (7).

These findings support GLP-1 agents as cardiometabolic protective therapies.

Chronic Kidney Disease in Type 2 Diabetes

The FLOW trial showed semaglutide reduced the risk of kidney disease progression, kidney failure, and cardiovascular events in patients with T2D and CKD (8).

NEW: Fatty Liver Disease / MASH

In 2025, the FDA approved semaglutide injection for metabolic-associated steatohepatitis (MASH) with moderate-to-advanced fibrosis. Clinical trials demonstrated histologic improvement in liver inflammation and fibrosis (9).

MASH is a progressive form of fatty liver disease that can lead to cirrhosis, liver failure, and hepatocellular carcinoma.

Obstructive Sleep Apnea (OSA)

Tirzepatide received FDA approval for treatment of moderate-to-severe OSA in adults with obesity, improving apnea severity along with weight loss (10).

Oral vs Injectable GLP-1

A newer oral semaglutide formulation offers a daily pill alternative. Absorption requires strict timing and fasting conditions, and GI side effects are similar to injectable forms (11).

Common Side Effects

Most occur during dose escalation and are dose-dependent:

• Nausea
• Vomiting
• Constipation or diarrhea
• Early satiety (12)

Hair Loss During GLP-1 Therapy

Hair shedding is typically due to telogen effluvium, triggered by rapid weight loss, caloric deficit, and protein or micronutrient insufficiency (13). This condition is usually temporary and resolves when nutrition stabilizes.

Muscle Loss During Weight Loss

Weight loss from any cause includes some lean mass loss. In a STEP-1 substudy, semaglutide reduced both fat and lean mass, though the majority of weight lost was fat (14). Similar findings were seen with tirzepatide (15).

Preserving lean mass is critical for metabolic health and aging.

Evidence-Based Strategies to Reduce Hair and Muscle Loss

Resistance Training

Progressive resistance exercise preserves lean mass during weight loss (16).

Adequate Protein Intake

Higher protein intake during caloric restriction supports lean mass retention, especially combined with resistance training (17).

Supplements With Supportive Evidence

(Supplements are adjuncts, not guaranteed treatments. Patients should consult a physician before use.)

Marine Collagen Peptides

Clinical studies of specific collagen peptide formulations show improvements in hair thickness and appearance (18,19).

Pumpkin Seed Oil

A randomized placebo-controlled trial showed increased hair counts in men with androgenetic alopecia using pumpkin seed oil (20).

BioSil® (choline-stabilized orthosilicic acid)

A double-blind study showed improved hair tensile strength and thickness with ch-OSA supplementation (21).

Nutrafol®

Randomized controlled trials report improved hair counts and hair quality metrics compared with placebo, though some studies involve industry sponsorship (22,23).

Supplements for Muscle Preservation

Creatine Monohydrate

Meta-analyses show creatine combined with resistance training increases lean mass and strength (24).

Protein Optimization

Adequate dietary protein remains the primary strategy for preserving lean mass (17).

Safety Considerations

GLP-1 medications are generally avoided in patients with:

• Medullary thyroid carcinoma history
• MEN2 syndrome
• Severe gastroparesis
• Prior severe pancreatitis (12)

Bottom Line

GLP-1 medications now provide:

Significant weight loss
Cardiovascular risk reduction
Kidney protection
FDA-approved treatment for MASH
Improvement in sleep apnea

When paired with adequate protein intake and resistance training, patients can protect muscle and reduce temporary hair shedding during weight loss.

These medications represent a major advancement in improving long-term healthspan when used under proper medical supervision.

References

•    Drucker DJ. Mechanisms of Action of GLP-1. Cell Metab. 2018.
•    Jastreboff AM et al. Tirzepatide Once Weekly for Obesity (SURMOUNT-1). N Engl J Med. 2022.
•    Wilding JPH et al. Once-Weekly Semaglutide in Adults with Obesity (STEP-1). N Engl J Med. 2021.
•    American Diabetes Association. Standards of Care in Diabetes 2025. Diabetes Care. 2025.
•    Lincoff AM et al. Semaglutide and Cardiovascular Outcomes in Obesity (SELECT). N Engl J Med. 2023.
•    Marso SP et al. Liraglutide and Cardiovascular Outcomes in T2D (LEADER). N Engl J Med. 2016.
•    Gerstein HC et al. Dulaglutide and Cardiovascular Outcomes (REWIND). Lancet. 2019.
•    Perkovic V et al. Semaglutide and CKD in Type 2 Diabetes (FLOW). N Engl J Med. 2024.
•    FDA. Approval of Semaglutide for MASH with Fibrosis. 2025.
•    FDA. Approval of Tirzepatide for Obstructive Sleep Apnea. 2024.
•    Oral Semaglutide Prescribing Information. FDA Label.
•    GLP-1 Receptor Agonist Prescribing Information, Safety Sections.
•    Malkud S. Telogen Effluvium Review. J Clin Diagn Res. 2015.
•    Wadden TA et al. Body Composition Changes with Semaglutide. Obesity. 2021.
•    Tirzepatide DXA Substudy, SURMOUNT-1. Obesity. 2023.
•    Peterson MD et al. Resistance Training and Lean Mass. Ageing Res Rev. 2011.
•    Morton RW et al. Protein Intake and Lean Mass Meta-analysis. Br J Sports Med. 2018.
•    Hexsel D et al. Oral Collagen Peptide Supplementation and Hair. J Cosmet Dermatol. 2017.
•    Collagen Peptides and Hair Thickness Trial. Nutrients. 2023.
•    Cho YH et al. Pumpkin Seed Oil and Hair Growth. Evid Based Complement Alternat Med. 2014.
•    Barel A et al. Choline-stabilized Orthosilicic Acid and Hair. Arch Dermatol Res. 2007.
•    Ablon G. Nutrafol RCT for Women’s Hair Growth. J Drugs Dermatol. 2018.
•    Nutrafol Clinical Study Data. Dermatol Ther. 2021.
•    Chilibeck PD et al. Creatine and Resistance Training Meta-analysis. J Strength Cond Res. 2017.