Nutritional Deficiencies on GLP-1 Medications: What You're Missing and How to Fill the Gaps
GLP-1 medications like semaglutide and tirzepatide have changed weight management and metabolic health. But as prescriptions rise, so does an important question: what happens to your nutrition along the way? A 2026 narrative review published in Clinical Obesity, analyzing data from 461,382 adults, found that 22% of GLP-1 users developed a nutritional deficiency within 12 months of starting treatment (Urbina et al., 2026). Understanding which nutritional deficiencies on GLP-1 medications are most common, and why they happen, is a practical first step toward protecting your health during treatment.
The good news: these gaps are manageable. With the right awareness, food choices, and targeted support, you can stay nourished while benefiting from your medication.
Why GLP-1 Medications Create Nutritional Gaps
GLP-1 receptor agonists work by suppressing appetite and slowing gastric emptying. That helps with weight management, but it also means you eat less overall. When total calorie intake drops significantly, so does your intake of essential vitamins and minerals.
Delayed gastric emptying can also alter how efficiently your body absorbs certain nutrients. Food sits in the stomach longer, which may affect nutrient uptake in the small intestine.
Rapid weight loss compounds the issue. Losing weight quickly increases your body's demand for protein, B vitamins, and minerals involved in bone and muscle maintenance. If intake is already low, that increased demand widens existing gaps.
Many adults also enter GLP-1 therapy with suboptimal nutrition to begin with. Pre-existing shortfalls in vitamin D, iron, or B12 can worsen once calorie intake declines. A 2025 Joint Advisory from the American College of Lifestyle Medicine, the American Society for Nutrition, the Obesity Medicine Association, and the Obesity Society highlighted nutritional monitoring as a priority for patients on GLP-1 therapy.
The Most Common Nutritional Deficiencies on GLP-1 Medications
Not all nutrients are equally affected. Here is what the data shows about GLP-1 vitamin deficiency patterns and the nutrients most at risk.
Vitamin D
Vitamin D is the most commonly reported deficiency among GLP-1 users. In the Urbina et al. review, 13.6% of users were deficient in vitamin D by the 12-month mark. A separate analysis within the same review (Salvatore et al., cited in Urbina et al., 2026) found that GLP-1 users had a 49% higher risk of vitamin D deficiency compared to SGLT2 users and a 32% higher risk compared to DPP-4 users.
Vitamin D plays a role in calcium absorption, bone health, and immune function. Because it is partly obtained through dietary sources like fatty fish, fortified dairy, and eggs, reduced food intake can meaningfully lower your levels.
Iron
Iron is another nutrient that deserves attention during GLP-1 therapy. Registry-level data shows that GLP-1 users had a 54% greater risk of low ferritin (an indicator of iron stores) compared to SGLT2 users. A prospective pilot study of 51 adults found that intestinal iron absorption dropped markedly after just 10 weeks of semaglutide treatment.
Low iron can contribute to fatigue, weakness, and difficulty concentrating. Because iron absorption depends on stomach acid and transit time, the gastric changes GLP-1 medications produce may reduce how much iron your body takes in from food.
B Vitamins
The B vitamin family, including B12, B1 (thiamine), and folate, is particularly vulnerable when calorie intake drops. These vitamins are water-soluble, meaning your body does not store large reserves. You need a consistent dietary supply.
B12 is found primarily in animal products, so anyone eating substantially less meat, dairy, or eggs may see levels decline. Thiamine and folate, found in whole grains, legumes, and leafy greens, can also fall short when overall food volume decreases. B vitamins support energy metabolism, nerve function, and red blood cell production.
Calcium, Magnesium, and Zinc
These three minerals often receive less attention, but each one matters during weight loss.
Calcium is critical for bone density, which can be affected during rapid weight loss. Adequate calcium intake, alongside vitamin D, supports bone health during periods of significant body composition change.
Magnesium supports muscle function, sleep quality, and hundreds of enzymatic reactions. Many adults already fall short of recommended intake even before starting GLP-1 therapy.
Zinc plays a role in immune function, wound healing, and the health of skin and hair. Reduced food intake, particularly of zinc-rich foods like red meat, shellfish, and seeds, can lower levels over time.
Muscle Loss: The Hidden Cost of Nutrient Gaps
Weight loss is the goal of GLP-1 therapy for many users, but not all weight loss is equal. Research suggests that up to 40% of the weight lost on GLP-1 medications can be lean muscle mass rather than fat (Neeland et al., 2024, as reviewed in Urbina et al., 2026), with real consequences for metabolism, strength, and long-term health.
Muscle loss during rapid weight loss is driven by insufficient protein intake, reduced physical activity, and shortfalls in nutrients that support muscle maintenance. When calorie intake drops sharply, the body can break down muscle tissue for energy.
HMB (beta-hydroxy beta-methylbutyrate), a metabolite of the amino acid leucine, has been studied for its role in supporting lean muscle preservation. Collagen peptides provide amino acids that support connective tissue, skin elasticity, and hair health, areas that can be affected during rapid weight change.
Prioritizing protein at every meal, staying active with resistance training, and addressing GLP-1 nutrient deficiency patterns through targeted support can all help protect lean body mass during treatment.
How to Support Your Nutrition on GLP-1 Medications
Maintaining good nutrition on GLP-1 therapy requires intentionality. Here are practical strategies aligned with recommendations from leading medical and nutrition organizations.
Prioritize nutrient-dense foods. When you are eating less overall, every bite counts. Focus on foods that deliver a high concentration of vitamins, minerals, and protein per calorie: leafy greens, lean proteins, eggs, nuts, seeds, and whole grains.
Make protein a priority at every meal. Protein supports muscle retention, satiety, and recovery. Many clinicians recommend 1.0 to 1.2 grams of protein per kilogram of body weight daily during GLP-1 therapy, though individual needs vary.
Consider targeted supplementation. Given the specific deficiency patterns associated with GLP-1 use, look for vitamins for GLP-1 therapy that address the nutrients most at risk: vitamin D, iron, B vitamins, magnesium, zinc, and calcium. A general multivitamin may not provide adequate amounts of each.
Stay on top of hydration and electrolytes. Reduced food intake also means reduced intake of electrolytes like sodium, potassium, and magnesium. Dehydration and electrolyte imbalances can contribute to fatigue, headaches, and muscle cramps. Consistent water intake and electrolyte-rich foods or supplements support hydration.
Get regular bloodwork. Routine lab monitoring helps catch deficiencies early. Ask about checking vitamin D, B12, ferritin, and a comprehensive metabolic panel at baseline and at regular intervals during treatment.
How Alula Helps Fill Nutritional Gaps for GLP-1 Users
Alula is a daily nutritional support product designed for adults, including those on GLP-1 medications. Rather than piecing together individual supplements, Alula addresses multiple common gaps in one daily serving.
Here is what Alula includes and why each component matters for GLP-1 users:
Full vitamin and mineral panel — including vitamin D, B vitamins, zinc, and other nutrients frequently depleted during GLP-1 therapy. This helps fill nutritional gaps that reduced calorie intake can create.
Electrolytes — sodium, potassium, and magnesium to support hydration, which can be harder to maintain when food intake is lower.
1,500 mg calcium HMB monohydrate — HMB supports muscle retention, an important consideration when up to 40% of weight lost on GLP-1s can be lean mass.
2g collagen peptides — supports skin and hair health, areas that can be affected during periods of rapid weight change.
2g fiber from partially hydrolyzed guar gum — supports digestive comfort, which many GLP-1 users find valuable given the gastrointestinal changes these medications can produce.
Bacillus coagulans probiotic (approximately 2 billion CFU) — supports gut health and digestive balance.
250mg ginger root extract (5% gingerols) — supports digestive comfort, a common concern for adults on GLP-1 therapy.
Alula was built with the nutritional landscape of GLP-1 therapy in mind.
Learn more about Alula and how it supports your nutrition during GLP-1 treatment.
Frequently Asked Questions
What vitamin deficiencies are common with GLP-1 medications?
The most commonly reported deficiency is vitamin D, followed by iron, B12, thiamine, folate, calcium, magnesium, and zinc. A 2026 review of over 461,000 adults found that 22% of GLP-1 users developed at least one nutritional deficiency within 12 months. These gaps are driven by reduced calorie intake, altered nutrient absorption, and the increased demands that accompany rapid weight loss.
Can GLP-1 medications cause iron deficiency?
Research suggests they can contribute to it. GLP-1 users have a 54% greater risk of low ferritin compared to users of other diabetes medications. A pilot study found that intestinal iron absorption dropped notably after 10 weeks of semaglutide. Reduced food intake, combined with changes in gastric function, may limit how much dietary iron the body absorbs. Ask your healthcare provider about monitoring your ferritin levels.
How can I prevent muscle loss while taking GLP-1 medications?
Three strategies matter most: adequate protein intake (aim for 1.0 to 1.2 grams per kilogram of body weight daily), regular resistance or strength training, and targeted nutritional support. Research indicates up to 40% of weight lost on GLP-1 medications can be lean muscle mass (Neeland et al., 2024). Compounds like HMB have been studied for their role in supporting muscle retention during weight loss.
Should I take a multivitamin while on Ozempic or Wegovy?
A standard multivitamin may not provide enough of the specific nutrients most affected by GLP-1 therapy. Look for a product that delivers meaningful amounts of vitamin D, B12, iron, magnesium, zinc, and calcium, and that also addresses muscle retention, hydration, and digestive comfort. Alula, for example, was designed for adults on GLP-1 medications and combines a full vitamin and mineral panel with HMB, electrolytes, fiber, collagen, and digestive support in one daily serving.
How does Alula support GLP-1 users?
Alula is designed for adults, including those on GLP-1 medications. It helps fill nutritional gaps with a comprehensive vitamin and mineral panel, supports hydration with electrolytes, supports muscle retention with 1,500 mg calcium HMB monohydrate, supports skin and hair health with collagen peptides, and supports digestive comfort with fiber, a probiotic, and ginger root extract. One daily serving covers multiple areas of nutritional support.
Take Care of the Nutrition Your Medication Cannot
GLP-1 medications are a meaningful tool for weight management and metabolic health. But they were not designed to manage your nutrition, and the data makes clear that GLP-1 malnutrition is a real and measurable risk. Being proactive about your diet, monitoring your labs, and using targeted nutritional support can help you stay nourished and energized throughout treatment.
Alula was designed to make that easier. One daily serving, built around the specific nutritional needs of adults on GLP-1 therapy.
Learn more about Alula and start filling the gaps today.