GLP-1 Receptor Agonists
Common brand names: Semaglutide (Ozempic/Wegovy), Tirzepatide (Mounjaro/Zepbound), Liraglutide (Victoza)
Three nutrients listed against this medication. The most severe is marked critical.
One of the three is marked well documented. The other two carry their own evidence levels.
At a glance
- Muscle Mass (Lean Body Mass)Critical · Well documented
- Vitamin B12Mild · Traditionally cited, limited evidence
- Vitamin D & CalciumMild · Traditionally cited, limited evidence
Color shows how serious each listed effect is. The label beside it shows how strong the evidence is. The cards below explain each one and show its evidence.
Mechanism, GLP-1 agonists cause rapid weight loss, and a substantial share of the weight lost is lean muscle mass rather than fat. Background figure, not from a trial cited on this record. This accelerates sarcopenia Age-related loss of muscle mass and strength. (age-related muscle loss), which is already the primary driver of frailty and mortality in aging. Inadequate protein intake during GLP-1 therapy dramatically worsens this.
Common signs, Weakness, reduced strength metrics, fatigue, loss of functional capacity, worsened body composition despite weight loss
Wilding et al. (N Engl J Med, 2021; PMID PubMed ID: the permanent number the US National Library of Medicine gives a published paper. Each one links to that paper's record on PubMed. 33567185): in the STEP-1 semaglutide trial, substantial weight loss included significant loss of lean body mass.
Protein intake in studies was at least 1.2–1.6 g/kg/day, ideally from complete sources (whey, eggs, meat). Creatine monohydrate 5 g/day is among the most evidence-supported interventions for preserving lean mass during caloric restriction, and resistance training is strongly emphasized.
Mechanism, GLP-1 agonists slow gastric emptying and reduce food intake, and B12 absorption depends on gastric acid and intrinsic factor. The documented drug-related B12 depletion belongs to metformin, not to this class; the gastric-emptying route is a theoretical concern that has not been measured on GLP-1 therapy.
Common signs, Fatigue, neuropathy, cognitive impairment, macrocytic anemia (often slow to develop)
B12 depletion is documented for metformin, not GLP-1 agonists; slowed gastric emptying is a theoretical, unproven concern.
Methylcobalamin 1,000 mcg daily is a figure in common use, not from a trial cited on this row, and the row's own evidence states that B12 depletion is documented for metformin rather than for GLP-1 agonists. Sublingual and injectable routes bypass gastric absorption, which is why they are chosen in practice.
Mechanism, Appetite suppression on GLP-1 agonists can cut total caloric intake sharply, and any large reduction in food intake reduces micronutrient intake with it. The concern is extrapolated from very-low-calorie and bariatric populations; no GLP-1 trial has measured vitamin D or calcium status.
Common signs, Bone density loss, compounding muscle weakness, immune impairment
Extrapolated from very-low-calorie and bariatric analogies; there are no GLP-1 depletion data. Protein and nutritional adequacy during rapid weight loss is the open question.
Vitamin D3 2,000–5,000 IU/day with K2 (MK-7) 100–200 mcg daily, and calcium from food, is the pattern in common use, not from a trial cited on this row. A total calcium intake of 1,000–1,200 mg/day is a general population figure, not a GLP-1 finding; the row's own evidence states there are no GLP-1 depletion data.
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These statements have not been evaluated by the Food and Drug Administration. Any grade on this page describes the strength of published human trial evidence in the populations studied. It is not a recommendation for any individual and is not medical advice. Starting, stopping or changing any supplement or medication is a decision for your physician.
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