What Nutrients Are You Lacking When Taking GLP-1s?

abWeight Loss
Written By Lisa Hanlon

GLP-1 medications such as Ozempic, Wegovy and Mounjaro have transformed the way we manage obesity, insulin resistance, and metabolic health. For many people, they are life-changing. But as their use grows, so does something I see every week in clinic that is often overlooked - nutritional inadequacy.

These medications suppress appetite and slow digestion. This helps with weight loss and blood sugar control. However, it can also mean people eat significantly less food overall, which increases the risk of nutrient deficiencies if diet quality is not prioritised.

For women in perimenopause, menopause, or cancer survivorship, people I commonly support in clinic, this matters even more. Nutritional gaps can affect bone health, muscle mass, metabolic function, energy, and long-term health outcomes.

I’d like to explore here what the latest research is showing.

Why Nutrient Deficiencies Can Occur on GLP-1 Medications

GLP-1 medications work by:

  • Reducing appetite

  • Slowing gastric emptying

  • Increasing feelings of fullness

  • Reducing ‘food noise’

While this can improve metabolic health, it often results in smaller meal sizes and reduced food variety. If not carefully managed, this can lead to inadequate intake of both macro and micronutrients.

Researcher and health experts are increasingly concerned that without structured nutrition support, we may ‘replace one set of health problems with another’ (Spreckley et al, 2026).

This is particularly relevant for individuals already at risk of deficiency, including:

  • Women over 40

  • People with metabolic disease

  • Cancer survivors

  • Individuals with a history of dieting or restrictive eating

The Most Common Nutrient Deficiencies in GLP-1 Users

A recent dietary analysis of people using GLP-1 medications found that most participants were not meeting recommended intakes for vitamin D, iron, calcium, and protein (Urbina et al, 2026).

Here are the key areas of concern that have been found:

1. Protein

Protein is one of the most important nutrients to prioritise when using GLP-1 medications because:

  • Appetite suppression can reduce protein intake.

  • Rapid weight loss increases the risk of lean muscle loss.

  • Muscle is essential for metabolic health, longevity and glucose regulation.

Low protein intake can lead to:

  • Fatigue

  • Reduced metabolic rate, leading to rebound weight gain if you stop taking GLP-1s

  • Loss of strength

  • Increased frailty risk later in life

For women in menopause or anyone in cancer recovery, preserving muscle mass is critical.

2. Vitamin D and Calcium

Vitamin D deficiency appears particularly common in GLP-1 users. In some reports, almost all users fall short of recommended intake (Spreckley et. al, 2026; Urbina et. al, 2026)

This matters because:

  • Vitamin D and calcium work together for bone health

  • Weight loss without adequate intake can accelerate bone loss

  • This risk is already elevated in menopause and breast cancer survivorship

Over time, this can increase the risk of osteopenia, osteoporosis and fractures.

3. Iron

Iron deficiency is another concern, especially for women.

Reduced intake of red meat, legumes and wholegrains, combined with smaller portions may contribute to fatigue, low energy, and reduced exercise capacity.

For cancer survivors or active women, iron status is essential for quality of life and recovery. Iron deficiency increases the risk of all-cause mortality (Cannon et. al, 2024).

4. Fibre and Gut Health

Many people on GLP-1 medications consume far less fibre than recommended, which may worsen constipation and impact gut microbiome health (Urbina et. al, 2026).

Fibre plays a role in:

  • Blood sugar control

  • Hormone balance

  • Gut health

  • Satiety

  • Cardiometabolic health

This is particularly important in women navigating perimenopause and metabolic changes or anyone with gut health issues. It is recommended for adults to consume at least 25gm-30gm of fibre every day.

5. Magnesium, Potassium and Other Micronutrients

Reduced food volume can also affect intake of:

  • Magnesium

  • Potassium

  • Antioxidant vitamins

  • Trace minerals

These nutrients are essential for:

  • Energy production

  • Muscle and nerve function

  • Heart health

  • Stress resilience

Why This Matters for Long-Term Health

GLP-1 medications are not a standalone solution. They are most effective when combined with a personalised nutrition and lifestyle strategy.

Without this support, potential consequences include:

  • Loss of muscle mass

  • Reduced metabolic flexibility

  • Bone density loss

  • Nutrient deficiencies

  • Weight regain after stopping GLP-1 medication

This is why nutritional screening and monitoring should be part of any GLP-1 treatment plan.

A Food-First, Personalised Approach

As a clinical nutritionist, my approach is always:

  • Food first (supplements where required)

  • Personalised and strategic

  • Evidence-based

  • Focused on long-term health

For many clients, this includes:

  • Protein targets to preserve muscle and achieve satiety

  • Nutrient-dense meal planning

  • Blood testing and monitoring

  • Gut and metabolic support

  • Targeted supplementation when needed

  • Extra support during menopause or cancer recovery

Every mouthful matters when appetite is reduced. Nutrient density becomes the priority.

The Bottom Line

GLP-1 medications can be powerful tools for metabolic health and weight management. But they should never replace good nutrition. Instead, they should be supported by a structured, personalised plan that protects muscle, supports bone and metabolic health, and builds sustainable long-term outcomes.

Real health isn’t just about weight loss, it’s about resilience, strength, and setting you up for success long after the GLP-1 medication stops.

Would You Like Support While Using GLP-1 Medications?

If you are currently using, or considering, GLP-1 medications and want to:

  • Preserve muscle

  • Prevent nutrient deficiencies

  • Support menopause or survivorship health

  • Create a realistic long-term strategy

You can book a 15-minute discovery call to see how we can work together.

Book here

References

Cannon, E. J., Misialek, J. R., Buckley, L. F., Aboelsaad, I. A. F., Ballantyne, C. M., Leister, J., Pankow, J. S., & Lutsey, P. L. (2024). Anemia, Iron Deficiency, and Cause-Specific Mortality: The Atherosclerosis Risk in Communities Study. Gerontology, 70(10). https://doi.org/10.1159/000539973

Spreckley, M., Ruggiero, C.F. and Brown, A. (2026). Nutrition Strategies for Next-Generation Incretin Therapies: A Systematic Scoping Review of the Current Evidence. Obesity Review, Jan 7. https://pubmed.ncbi.nlm.nih.gov/41500509/

Urbina, J., Salinas-Ruiz, L.E., Valenciano, C. and Clapp, B. (2026). Micronutrient and Nutritional Deficiencies Associated With GLP-1 Receptor Agonist Therapy: A Narrative Review. Clinical Obesity,16(1). https://pubmed.ncbi.nlm.nih.gov/41549912/

Lisa Hanlon
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