How They Work Together for Weight Loss

As GLP-1 medications reshape the weight-loss landscape, peptides are becoming part of the conversation around optimizing results. If you’re unfamiliar with what that means, you’re in the right place. Ahead, a registered dietitian and nutritionist breaks down what peptides are and how they may work alongside GLP-1 medications to support weight management.

Featured Experts

• Sahar Berjis is a registered dietitian and the founder of Inner Health and Wellness
• Jennifer Hanway is a holistic nutritionist

GLP-1s vs. Peptides

Although GLP-1s are technically peptides, they function very differently in the body than non-GLP-1 peptides. “Peptides are short chains of amino acids, designed to support the body by functioning like tiny messengers,” says Sahar Berjis, a registered dietitian and the founder of Inner Health and Wellness. “They play roles in nearly every system in the body, including metabolism, muscle preservation, gut health, hormone balance, inflammation and recovery.”

In practice, peptides are prescribed and administered under the care of a medical provider and span a wide range of wellness categories. One familiar example is copper peptides, which have been used in dermatology for years to support skin health and repair.

When it comes to weight management, peptides work in a similarly supportive way. While peptides don’t directly cause weight loss, they may support weight management in more indirect ways. As holistic nutritionist Jennifer Hanway explains, peptides don’t burn fat on their own. Instead, they influence processes that affect body weight, such as appetite regulation, insulin sensitivity, inflammation, muscle maintenance and gut health.

GLP-1s work differently. They’re an outlier in how directly they act on appetite and blood sugar regulation. “They slow gastric emptying and improve glucose-dependent insulin secretion, allowing the majority of weight loss to come from a sustained reduction in caloric intake rather than direct correction of underlying metabolic dysfunction,” Hanway explains.

Do Peptides Have Side Effects?

Like all medications and supplements, peptides can come with side effects, which vary based on several factors. The type of peptide, dosage, method of administration and an individual’s physiology can all influence how the body responds. “Side effects tend to show up when the body is pushed too hard or given something it doesn’t need—which is why individualized guidance matters,” says Berjis.

Common side effects are typically mild and may include nausea, headaches, temporary fatigue, changes in sleep quality or irritation at the injection site for injectable peptides. According to Hanway, more serious adverse effects are often linked to non-clinical use, such as stacking multiple peptides without proper monitoring or using supraphysiologic doses, rather than the peptides themselves. She adds that issues can also stem from lifestyle factors, including under-eating, inadequate protein or calorie intake and lack of regular exercise.

Can Peptides & GLP-1s Be Used Together?

The experts agree the two can be used together when approached thoughtfully and under medical guidance. “A combination approach helps address common challenges associated with GLP-1 use, including loss of lean mass, reduced metabolic rate, gastrointestinal discomfort and slower tissue repair,” says Hanway. Berjis adds that the goal isn’t rapid weight loss at all costs. When used appropriately, GLP-1s and peptides can support weight loss without compromising energy, strength or overall well-being.

What to Expect When Using GLP-1s & Peptides

You may wonder whether combining GLP-1s and peptides increases the risk of side effects. In some cases, the opposite may be true. GLP-1s are commonly associated with nausea, constipation, fatigue and under-eating. Berjis says that certain supportive peptides may help offset these effects by aiding digestion, supporting hydration and recovery and reducing burnout. More often than not, adverse effects stem from inadequate nutrition, insufficient protein intake or pushing the body too aggressively rather than from the combination itself.