When you’re eating significantly less than you used to, the gaps that appear in your nutrition aren’t obvious. You feel less hungry, you eat less, and the assumption is that less food equals fewer problems.
The reality is that reduced food intake creates specific nutritional vulnerabilities — and GLP-1’s effects on digestion and gut motility can make absorption less efficient on top of that. After 14 months on GLP-1 and several conversations with my provider, here’s what I actually take and why.
Non-Negotiable: Protein
Not technically a supplement, but protein intake deserves to be at the top of this list because it’s where most GLP-1 users fall short. Reduced appetite means reduced eating, and reduced eating without attention to protein composition means the body pulls from muscle to make up the deficit.
Target: 100 grams per day minimum. 120 grams if you’re doing any resistance training. A protein powder or shake is a practical tool for hitting this when appetite won’t cooperate with whole food sources.
Creatine
Creatine is the most research-backed supplement for muscle retention during caloric restriction — directly relevant to what GLP-1 users need. It supports energy production within muscle cells during resistance training and improves recovery between sessions.
5 grams daily, taken consistently regardless of training days. No loading phase required with modern forms.
I use Arq8 FullDissolve nano-creatine — dissolves completely, absorbs faster than standard powder, no gritty texture.
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Vitamin D
Vitamin D deficiency is common in the general population and significantly more common in people who are overweight or obese — Vitamin D is fat-soluble and gets sequestered in fat tissue rather than circulating where it can be used. As GLP-1 produces weight loss and fat tissue decreases, Vitamin D stored in fat cells releases into circulation, but this process takes time and the deficit is real in the interim.
Get your Vitamin D level tested. Most providers recommend a serum level above 40 ng/mL. 2,000 to 4,000 IU daily is a common supplementation range, adjusted based on your actual level.
Magnesium
Magnesium is involved in hundreds of enzymatic processes, including blood sugar regulation, muscle function, and sleep quality — all relevant on GLP-1. Dietary magnesium is often low even without caloric restriction. On reduced food intake it’s more likely to be insufficient.
Magnesium glycinate or magnesium malate are the better-absorbed forms. Magnesium oxide is cheap and widely available but poorly absorbed. 300 to 400 mg before bed supports sleep quality and muscle recovery.
Iron and Ferritin (Women Specifically)
Low iron — particularly low ferritin, the stored form — is one of the most common nutritional deficiencies in women and a direct contributor to fatigue and hair loss. Both fatigue and hair loss are already associated with GLP-1 and rapid weight loss. Low iron makes both significantly worse.
Have your ferritin level checked rather than guessing. Many providers use 50 ng/mL as the threshold for intervention even when standard iron levels look normal. If ferritin is low, an iron supplement with Vitamin C (which improves absorption) is the standard approach.
Zinc
Zinc supports immune function, hair follicle health, and protein synthesis. Reduced food intake leads to reduced zinc intake. Particularly relevant for anyone experiencing GLP-1-related hair loss.
15 to 30 mg daily. Take with food to reduce the stomach discomfort that zinc causes on an empty stomach.
Collagen
As skin elasticity changes with weight loss — particularly rapid weight loss — collagen supports skin structure and joint health. It also adds protein to your daily intake, which is useful when appetite is limited.
I add collagen peptides to my morning coffee. One scoop, unflavored, no taste change. The collagen I use is from Physician Crafted — physician-formulated, clean ingredient list.
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What I Don’t Take
A few things commonly marketed for weight loss that I’ve skipped, and why:
Fat burners and thermogenics. GLP-1 is already creating a caloric deficit through appetite suppression. Stimulant-based fat burners add heart rate and blood pressure stress without meaningful additional benefit. Not worth it.
Appetite suppressants. The medication handles this. Adding a supplement that does the same thing is redundant and introduces unnecessary variables.
Detoxes and cleanses. Not a category I find credible regardless of GLP-1 status. Nothing here changes that.
The Practical Approach
Start with the ones that address the most common GLP-1-specific vulnerabilities: protein (food first, supplement when needed), creatine, Vitamin D, and magnesium. Get ferritin tested and address it if low. Add collagen if joint support or skin elasticity is a concern.
The list doesn’t need to be long. Getting the high-impact ones consistently beats a complicated protocol you don’t follow.