The Single Biggest Nutrition Mistake My Patients Make on GLP-1’s

By: Kevin Huffman, D.O.

The single biggest mistake I see patients make while taking GLP-1 medications is failing to protect their muscle mass.

These medications are extremely effective at reducing appetite and accelerating weight loss. Patients eat less, lose weight quickly, and see encouraging changes on the scale.

But the scale does not tell the whole story.

A significant portion of that weight loss can come from muscle, not fat, if proper nutrition and resistance training are not in place.

This is a serious metabolic problem.

Why Muscle Loss Happens on GLP-1 Medications

GLP-1 medications create a substantial calorie deficit by suppressing appetite. When calorie intake drops sharply, the body looks for alternative sources of energy.

It does not use fat exclusively. It also breaks down muscle tissue.

Muscle is metabolically active and easier for the body to convert into energy than stored fat. Without adequate protein intake and muscle stimulus, muscle loss becomes inevitable.

Research shows that up to 40 percent of weight lost during calorie restriction can come from lean muscle mass if preventative measures are not taken (Blundell et al., 2017).

This condition is known as sarcopenia.

Patients may reach a lower body weight, but their metabolic health worsens. Their metabolism slows, their strength declines, and their risk of weight gain increases.

Clinical evidence also shows that weight regain commonly occurs after discontinuation of GLP-1 therapy, largely due to metabolic adaptation and reduced energy expenditure (Wilding et al., 2022).

Why Muscle Loss Makes Weight Regain More Likely

Muscle regulates metabolic rate.

The more muscle you have, the more calories your body burns even at rest. When you lose muscle, your metabolic rate drops.

This creates a dangerous situation.

Patients finish treatment with a slower metabolism than when they started. When normal eating resumes, their body burns fewer calories, making weight regain highly likely.

This is why many patients regain weight after stopping GLP-1 medications.

They did not just lose fat. They lost their metabolic engine.

How to Prevent Muscle Loss While Taking GLP-1 Medications

Preventing muscle loss requires intentional action. There are three non-negotiable steps.

1. Consume Adequate Protein Every Day

Most patients need approximately 100 grams of protein per day to preserve muscle mass during active weight loss.

This is difficult to achieve through food alone because appetite is reduced.

Protein supplementation is often necessary. High quality, medical grade protein provides essential amino acids in a small volume, making it easier to meet daily requirements.

Without sufficient protein, muscle loss accelerates.

2. Eat Protein First at Every Meal

GLP-1 medications limit how much you can eat.

This makes food order critical.

Protein must be consumed first. If fullness occurs quickly, protein intake has already been secured.

If patients fill their stomach with carbohydrates first, they will not consume enough protein to protect muscle.

This is a simple but essential behavioral adjustment.

3. Perform Resistance Training Weekly

Muscle must be stimulated to be preserved.

Resistance training signals the body that muscle tissue is necessary. Without this signal, the body will break muscle down.

Patients should perform resistance training at least two to three times per week.

Walking alone is not sufficient.

Resistance training has been shown to significantly preserve lean muscle mass during weight loss interventions and is essential for maintaining metabolic health (Wewege et al., 2024).

The Real Goal Is Metabolic Protection

GLP-1 medications are powerful tools. They help patients lose weight effectively.

But weight loss without muscle preservation creates long term metabolic consequences.

The objective is not simply to weigh less.

The objective is to preserve muscle, maintain metabolic rate, and create sustainable metabolic health.

Patients who prioritize protein intake and resistance training achieve better long term outcomes.

Patients who do not often regain weight.

Protecting muscle is not optional.

It is essential.

References

Blundell, J., Finlayson, G., Axelsen, M., Flint, A., Gibbons, C., Kvist, T., Hjerpsted, J. B., & Caixas, A. (2017). Effects of once-weekly semaglutide on appetite, energy intake, control of eating, food preference and body weight in subjects with obesity. Diabetes, Obesity and Metabolism, 19(9), 1242–1251. https://repository.lboro.ac.uk/articles/journal_contribution/A_review_of_the_effects_of_glucagon-like_peptide-1_receptor_agonists_and_sodium-glucose_cotransporter_2_inhibitors_on_lean_body_mass_in_humans/10120382

Wilding, J. P. H., Batterham, R. L., Davies, M., Van Gaal, L. F., Kandler, K., Konakli, K., Lingvay, I., & le Roux, C. W. (2022). Weight regain and cardiometabolic effects after withdrawal of semaglutide: The STEP 1 trial extension. Diabetes, Obesity and Metabolism, 24(8), 1553–1564. https://discovery.ucl.ac.uk/id/eprint/10149199/1/Diabetes%20Obesity%20Metabolism%20-%202022%20-%20Wilding%20-%20Weight%20regain%20and%20cardiometabolic%20effects%20after%20withdrawal%20of%20semaglutide%20.pdf

Wewege, M. A., Thom, J. M., Rye, K. A., & Parmenter, B. J. (2024). Resistance training prevents muscle loss during weight loss interventions: A systematic review and meta-analysis. Sports Medicine. https://pubmed.ncbi.nlm.nih.gov/38078578/

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Contributed by: 

Kevin Huffman, D.O., is a board‑certified bariatric physician and the Medical Director of AmBari Nutrition. With over 10,000 patients treated and more than three decades of experience in bariatric medicine, Dr. Huffman is recognized nationwide for his expertise in obesity treatment, medical weight loss, and practitioner training.