GLP-1-based medications such as Wegovy and Ozempic (semaglutide) and Mounjaro (tirzepatide) are increasingly being used to support weight loss and blood sugar control. In the UK, Wegovy and Mounjaro are licensed for weight management, while Ozempic is licensed for type 2 diabetes.
As a nutritional therapist, I often see that the clients who feel best and achieve the most sustainable outcomes are those who combine GLP-1 therapy with targeted nutritional support.
Understanding What GLP-1 Medications Do
These medications work by mimicking glucagon-like peptide-1 (GLP-1), a hormone your gut releases after eating that plays a key role in appetite, digestion and blood sugar control. Mounjaro also mimics a second gut hormone, GIP, which is why it's sometimes described as a dual-action medication. For simplicity, this article uses "GLP-1 medications" to cover all three.
One of the primary effects of GLP-1 medications is slowing gastric emptying, meaning food stays in the stomach for longer. This enhances feelings of fullness and satiety after meals, often leading to smaller portion sizes and reduced snacking. While this can support calorie control and weight loss, it may also increase the likelihood of nausea, bloating, reflux or a heavy feeling after eating, particularly if meals are large or poorly balanced.
GLP-1 medications also act on appetite centres in the brain, helping to reduce hunger signals and food cravings, especially for highly palatable, ultra-processed foods. For many people this can feel like a welcome relief from constant thoughts about food. However, a significantly reduced appetite can make it more challenging to consume adequate protein, fibre and essential micronutrients, increasing the risk of fatigue, muscle loss and nutrient deficiencies over time.
In addition, GLP-1 medications help regulate blood sugar. They increase the amount of insulin your body releases after a meal and reduce how much glucose your liver releases when it isn't needed. Insulin sensitivity also tends to improve as weight comes down. Because the insulin boost only happens when blood sugar is raised, these medications rarely cause low blood sugar on their own, although the risk is higher if they're combined with certain diabetes medicines such as insulin or sulphonylureas. Food quality, meal composition and timing still matter, and eating or drinking too little can still leave you tired, dizzy or light-headed.
Although these combined effects can be highly effective for weight loss and metabolic improvement, they also increase the likelihood of unintended consequences such as reduced overall food intake, digestive discomfort, constipation, low energy and nutrient shortfalls—particularly if nutrition is not proactively addressed.
This is where personalised nutrition becomes essential. Tailored nutritional support helps ensure that even with a reduced appetite, the body receives adequate protein, key micronutrients and digestive support. It also helps minimise side effects, protect muscle mass, stabilise energy levels and support long-term metabolic health, creating a safer and more sustainable approach alongside GLP-1 therapy.
Why Nutrition Matters Alongside GLP-1 Therapy
Helps Protect Muscle Mass
Rapid weight loss without adequate protein intake significantly increases the risk of lean muscle loss, not just fat loss. Loss of muscle tissue is particularly important to avoid, as muscle plays a key role in metabolic health, strength and long-term weight regulation. When muscle mass is reduced, it can:
Slightly lower resting metabolic rate, meaning the body burns a little less energy at rest
Reduce physical strength, stamina and overall energy levels
Make it harder to stay active and maintain results long term. When medication is stopped, appetite typically returns, and research shows most people regain a significant proportion of the weight they lost. Preserving muscle and building strong eating habits during treatment puts you in a better position if that happens.
A nutrition plan that prioritises sufficient, high-quality protein, evenly distributed across meals and snacks, helps preserve lean muscle mass during weight loss. This approach also supports satiety, blood sugar stability and metabolic health, making weight loss safer, more sustainable and easier to maintain long term.
Supports Digestive Comfort and Gut Health
GLP-1 medications can commonly affect digestive function due to their impact on gastric emptying and appetite regulation. As a result, some clients experience symptoms such as:
Nausea, particularly if meals are too large or eaten too quickly
Bloating or abdominal discomfort
Constipation or sluggish digestion due to reduced food volume and slower gut motility
Acid reflux or a feeling of food sitting heavily in the stomach
Targeted nutritional support can significantly reduce these symptoms and improve day-to-day comfort. This may include:
Choosing easily digestible, nutrient-dense foods that are gentler on the digestive system
Adjusting meal size, texture and timing to suit slower digestion and reduced appetite
Supporting gut motility with appropriate fibre intake, adequate hydration and key micronutrients such as magnesium
Identifying and temporarily limiting foods that may worsen symptoms, such as high-fat, very fibrous or highly processed foods
Maintaining a healthy gut is not only important for digestive comfort but also plays a key role in appetite regulation, inflammation control and mental wellbeing, all of which support more sustainable outcomes while using GLP-1 therapy.
Avoids Nutrient Deficiencies
Because appetite is significantly reduced on GLP-1 medications, it can be easy to under-eat essential nutrients, even when food choices appear healthy. Research into exactly which nutrients run low in people on these medications is still limited, but based on reduced food intake, these are the ones most likely to be at risk:
Protein, which is critical for muscle preservation, metabolic health and satiety
Iron, needed for oxygen transport, energy levels and cognitive function
B vitamins, which support energy production, nervous system health and hormone balance
Magnesium, important for muscle function, stress regulation and digestion
Zinc, essential for immune function, wound healing and appetite regulation
Omega-3 fats, which support inflammation control, cardiovascular health and brain function
Over time, these nutrient shortfalls can contribute to a range of symptoms, including:
Persistent fatigue or low energy
Hair thinning or poor hair quality
Low mood, brain fog or reduced stress resilience
Poor recovery from exercise or daily activity
Hormonal disruption, including changes to menstrual health
Personalised nutrition ensures that every bite counts, focusing on nutrient-dense food choices and appropriate supplementation where needed. This approach helps deliver maximum nourishment, even with smaller portions, supporting overall health, energy and long-term success alongside GLP-1 therapy.
Improves Blood Sugar Stability and Energy Levels
Although GLP-1 medications help regulate blood sugar, food choices still play a crucial role. This may result in:
Blood sugar dips between meals
Dizziness or light-headedness, often linked to eating or drinking too little
Increased cravings, particularly for quick sources of energy
Low or unstable energy levels throughout the day
A nutrition plan focused on adequate protein, fibre-rich carbohydrates, healthy fats and overall micronutrient density helps promote steadier blood sugar responses. This approach supports sustained energy, improved satiety and reduced reliance on ultra-processed foods, allowing GLP-1 medications to work more effectively alongside long-term metabolic health.
Supports Long-Term Weight Maintenance
One of the biggest concerns with GLP-1 medications is weight regain after stopping treatment, particularly if rapid weight loss has occurred without addressing underlying habits, metabolic health and the relationship with food.
Ongoing nutrition support helps clients to:
Build sustainable eating habits that can be maintained beyond medication use
Improve metabolic flexibility, supporting the body’s ability to efficiently use both carbohydrates and fats for fuel
Address emotional and stress-related eating, which is often unchanged by medication alone
Reconnect with natural hunger and fullness cues, rather than relying solely on appetite suppression
Develop renewed confidence around food choices, portion sizes and meal timing
Together, these factors create a strong, supportive foundation for maintaining results long after medication is reduced or discontinued, helping weight loss feel more sustainable, empowering and health-focused rather than temporary.
Nutrition Is Not About Eating Less, it’s About Eating Smarter
GLP-1 medications can significantly change appetite and eating patterns, but they do not teach the body how to nourish itself optimally. Appetite suppression alone does not guarantee nutritional adequacy, metabolic resilience or long-term health. Nutrition bridges this gap by providing the body with the tools it needs to adapt and thrive during weight loss.
Targeted nutritional support helps to maintain:
Physical health, by preserving muscle mass and preventing nutrient deficiencies
Digestive comfort, by reducing common side effects and supporting gut function
Hormonal balance, which is closely linked to energy levels, mood and metabolic health
Mental wellbeing, by supporting brain chemistry, stress resilience and a healthier relationship with food
Long-term success, by building habits that support weight maintenance beyond medication use
When medication and nutrition work together, outcomes are not only more effective, but also safer, more comfortable and far more sustainable, supporting both short-term results and long-term wellbeing.
If you’re using a GLP-1 medication and want to feel your best while achieving lasting results, working with a nutritional therapist can make all the difference.
Book your free clarity call if you’d like more information on how a nutritionist could help you on your GLP-1 medication journey.
References
Wilding, J. P. H., et al. (2021). Once-weekly semaglutide in adults with overweight or obesity. New England Journal of Medicine, 384(11), 989–1002.
Jastreboff, A. M., et al. (2022). Tirzepatide once weekly for the treatment of obesity. New England Journal of Medicine, 387(3), 205–216.
Wilding, J. P. H., et al. (2022). Weight regain and cardiometabolic effects after withdrawal of semaglutide: the STEP 1 trial extension. Diabetes, Obesity and Metabolism, 24(8), 1553–1564.
Wharton, S., Davies, M., Dicker, D., Lingvay, I., Mosenzon, O., Rubino, D. M., & Pedersen, S. D. (2022). Managing the gastrointestinal side effects of GLP-1 receptor agonists in obesity: recommendations for clinical practice. Postgraduate Medicine, 134(1), 14–19.
Neeland, I. J., Linge, J., & Birkenfeld, A. L. (2024). Changes in lean body mass with glucagon-like peptide-1-based therapies and mitigation strategies. Diabetes, Obesity and Metabolism, 26(Suppl 4), 16–27.
Mozaffarian, D., et al. (2025). Nutritional priorities to support GLP-1 therapy for obesity: a joint advisory from the American College of Lifestyle Medicine, the American Society for Nutrition, the Obesity Medicine Association, and The Obesity Society. American Journal of Clinical Nutrition.
Written by Alison Diss Nutrition
Alison Diss is a BANT Registered Nutritional Therapist, Personal Trainer and founder of The Realign Method. She created The Realign Method after her own experience of burnout in a high-pressure career and has helped 100+ ambitious professionals achieve steady energy, a sharper mind and a stronger body. She's based in Surrey and works with clients UK-wide and online.