This article is for you if you’re exploring GLP-1 receptor agonist medications or are currently using them. The goal is to help you make informed choices, understand how these medications work, and recognise the kind of support you might need along the way.

What Are GLP-1 Receptor Agonists?

Glucagon-like peptide-1 (GLP-1) receptor agonists are medications that mimic hormones naturally produced by the gut (incretins). They work by promoting insulin secretion, delaying stomach emptying, and enhancing satiety (the feeling of fullness). These effects help regulate blood sugar levels and reduce appetite.

Originally developed to manage type 2 diabetes, certain GLP-1 medications are now also licensed for weight management:

• Liraglutide (Saxenda) – daily injection
• Semaglutide (Wegovy) – weekly injection
• Tirzepatide (Mounjaro) – weekly injection

Note: Semaglutide is also available as Ozempic (injection) and Rybelsus (oral), which are approved for type 2 diabetes treatment, not weight loss. However, Ozempic is frequently used off-label for weight management. Use of Ozempic for weight loss should only be done under medical supervision.

Wegovy and Mounjaro are currently labelled as “black triangle” drugs in the UK, under enhanced safety monitoring due to their recent approval for weight loss.

Who Are They For?

When used for weight loss, GLP-1 receptor agonists are typically prescribed for:

• Individuals with a body mass index (BMI) over 30 kg/m²
• Those with a BMI over 27 kg/m² who also have at least one weight-related health condition such as hypertension, dyslipidaemia, or cardiovascular disease

These are prescription-only medications and should always be used under medical supervision. Obtaining them from unreliable sources poses serious risks, including receiving unsafe products, incorrect dosing, and lack of proper medical monitoring.

How Do GLP-1 Agonists Work?

GLP-1 medications work by:

• Suppressing appetite
• Delaying stomach emptying and enhancing the sensation of fullness
• Regulating blood sugar levels and energy use

These combined effects can reduce energy intake and cause metabolic adaptations that lead to weight loss.

Are They Effective? (Updated Data 2025)

Clinical trials show that GLP-1 receptor agonists can lead to significant weight loss. A recent meta-analysis of 47 randomised controlled trials with 23,244 participants (Wong et al., 2025) found:

Average weight loss:

• Semaglutide: 7.2 kg (most effective medication)
• Liraglutide: 3.8 kg
• Overall (all medications): 4.6 kg

Important observations:

• Medications are much more effective in people without diabetes (average loss 9.2 kg) compared to those with diabetes (average loss 2.7 kg)
• The longer the treatment duration, the greater the weight loss
• Treatment >1 year lead to average loss of 8.0 kg, while treatment ≤1 year lead to 3.2 kg

However, it’s important to note:

• Discontinuation often leads to rapid weight regain. A 2025 meta-analysis (Berg et al., 2025) showed that those who took liraglutide regained an average of 2.2 kg, while those taking semaglutide/tirzepatide regained 9.7 kg.
• Long-term safety and effectiveness data remain limited
• Real-world data suggests medications are less effective than in trials, due to reduced adherence, lower dosing, and many users discontinuing within one year due to side effects or high cost

What Is “Food Noise” and How Do These Medications Affect It?

“Food noise” refers to persistent, intrusive thoughts about food, or heightened sensitivity to food cues. It can contribute to emotional eating or difficulty regulating eating behaviours.

GLP-1 medications may reduce food noise for some, but this can also mask underlying issues such as emotional distress or a disordered relationship with food. In some cases, hunger suppression may disconnect individuals from natural hunger and fullness cues, increasing the risk of nutritional deficiencies and malnutrition.

It’s worth noting that many people confuse food noise with preoccupation with food arising from restricted intake or strict dietary rules—a natural bodily response that subsides once adequate eating resumes and rigid food rules are challenged.

Side Effects to Be Aware Of

Common side effects:

• Nausea
• Vomiting
• Diarrhoea
• Constipation

Less common but serious side effects:

• Hypoglycaemia (even in people without diabetes)
• Gallstones
• Pancreatitis
• Allergic reactions
• Optic neuropathy (a type of vision loss)

Muscle Loss: A Significant Problem (New Data 2024-2025)

Recent research highlights a critical issue: muscle mass loss with GLP-1 medications can reach 15-40% of total weight loss. Studies from 2025 show that:

• Loss of fat-free mass may include a significant proportion of muscle mass
• This can lead to sarcopenia (significant loss of muscle mass and strength)
• Risk is greater in older adults, people with chronic kidney disease, liver disease, inflammatory bowel disease, and those who don’t exercise
• Can affect functionality, metabolism, and increase risk of falls and fractures

Other concerns:

• Loss of interest in food
• Disordered eating
• Nutritional deficiencies (protein, vitamins, minerals)
• Feelings of shame around medication use (“cheating” for weight loss)
• Physical and psychological effects from weight regain after stopping
• Limited availability for those who genuinely need them due to increased demand

What If You Have a Difficult Relationship with Food?

Research indicates that individuals most interested in GLP-1 medications often experience greater body dissatisfaction, weight stigma, disordered eating, and heightened focus on weight loss. This highlights the importance of carefully assessing treatment suitability and providing tailored support for these complex emotional and psychological needs.

For those with a history of eating disorders or a difficult relationship with food, GLP-1 medications may complicate the situation. Appetite suppression may feel rewarding at first but can lead to dangerous restriction and disconnection from intuitive hunger and fullness cues. It’s essential to assess for eating disorders or disordered eating before making decisions about weight loss medication as the treatment of choice.

The Role of the Dietitian

If you choose to use GLP-1 medications, working with a dietitian can provide vital support. A dietitian’s role during GLP-1 treatment includes:

1. Conducting a thorough nutritional assessment

Gaining a comprehensive understanding of individual needs before making treatment decisions and determining required support.

2. Optimising nutrition for muscle preservation and preventing nutritional deficiencies

The significant reduction in caloric intake with GLP-1 medications increases risk of nutritional deficiencies, particularly iron, calcium, magnesium, zinc, and vitamins A, D, E, K, B1, B12, and C.

Recent research shows that:

• Protein intake of 1.2-1.6 g/kg body weight daily helps preserve muscle mass
• Distributing protein across all meals is more effective
• Plant protein sources (legumes, nuts), fish, eggs, dairy, and lean poultry are good choice to support meeting protein needs
• Preventive supplementation for specific micronutrients (e.g., multivitamin, vitamin D, B12) may be necessary

Important: Increased protein intake alone is insufficient for muscle preservation—resistance training at least 3 times weekly is also required (as research suggests).

3. Preventing and managing side effects

Recommendations include smaller, more regular meals, guidance on meal composition, and individualised strategies for preventing and managing gastrointestinal issues.

4. Incorporating exercise programmes

Resistance training 2-3 times weekly combined with adequate dietary protein can reduce muscle mass loss by 30-50%.

5. Adopting sustainable habits

Supporting long-term health and weight maintenance after medication discontinuation.

6. Improving relationship with food

Working with a dietitian trained in this area can make a tremendous difference in your experience and provide substantial, targeted support.

All the above are very important, especially given that people starting GLP-1 medications often experience significant and unexpected changes in their daily life.

How Can I Help You?

I offer personalised nutritional support for those using or considering GLP-1 medications. My programmes include:

PCOS Nutrition Programme

For women with PCOS considering or using GLP-1 medications. Focus on hormonal balance, insulin resistance management, and muscle preservation.

Perimenopause & Menopause Support Programme

For women experiencing hormonal changes and considering GLP-1 medication. Support for symptom management and maintaining bone and muscle health.

Greek Mediterranean Lifestyle Programme

For weight management focusing on the Greek Mediterranean Diet. Sustainable approach without restriction.

Free Consultation

For more information, I’d be happy to speak with you in a free discovery call.

In Summary

GLP-1 receptor agonists may be a helpful tool for some, but should always be used under medical supervision with appropriate support. They are not a “magic solution”. For lasting health improvements, these medications must be combined with personalised nutritional guidance, psychological support, and sustainable, long-term lifestyle changes.

Key Points to Remember:

• GLP-1 medications are effective for weight loss
• Significant weight regain often occurs after discontinuation
• Muscle mass loss can reach 15-40% of total weight loss
• Nutritional support with adequate protein (1.2-1.6 g/kg) and resistance exercise is essential
• Those with eating disorder history need careful assessment
• Working with a dietitian can optimise outcomes and reduce side effects

References (Updated with Recent Studies from 2024-2025)

1. Drug safety update: GLP-1 receptor agonists. MHRA, UK. 2024.
2. GLP-1 Agonist Medications: Informed Consent Resource. Size Inclusive Medicine Society, 2023.
3. Ghusn W, Hurtado MD. Glucagon-like Receptor-1 agonists for obesity: Weight loss outcomes, tolerability, side effects, and risks. Obes Pillars. 2024 Aug 31;12:100127. doi: 10.1016/j.obpill.2024.100127. PMID: 39286601; PMCID: PMC11404059.
4. Hayashi D, Edwards C, Emond JA, Gilbert-Diamond D, Butt M, Rigby A, Masterson TD. What Is Food Noise? A Conceptual Model of Food Cue Reactivity. Nutrients. 2023 Nov 17;15(22):4809. doi: 10.3390/nu15224809. PMID: 38004203; PMCID: PMC10674813.
5. Markey CH, August KJ, Malik D, Richeson A. Body image and interest in GLP-1 weight loss medications. Body Image. 2025 Jun;53:101890. doi: 10.1016/j.bodyim.2025.101890. Epub 2025 Apr 22. PMID: 40267815.
6. Moiz A, Filion KB, Toutounchi H, et al. Efficacy and Safety of Glucagon-Like Peptide-1 Receptor Agonists for Weight Loss Among Adults Without Diabetes: A Systematic Review of Randomized Controlled Trials. Ann Intern Med. 2025 Feb;178(2):199-217. doi: 10.7326/ANNALS-24-01590.
7. Wong HJ, Sim B, Teo YH, et al. Efficacy of GLP-1 Receptor Agonists on Weight Loss, BMI, and Waist Circumference for Patients With Obesity or Overweight: A Systematic Review, Meta-analysis, and Meta-regression of 47 Randomized Controlled Trials. Diabetes Care. 2025 Feb;48(2):292-300. doi: 10.2337/dc24-1678.
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10. Mechanick JI, Butsch WS, Christensen SM, et al. Strategies for minimizing muscle loss during use of incretin-mimetic drugs for treatment of obesity. Obes Rev. 2025;26(1):e13841. doi: 10.1111/obr.13841.
11. Pantazopoulos D, Gouveri E, Papazoglou D, Papanas N. GLP-1 receptor agonists and sarcopenia: Weight loss at a cost? A brief narrative review. Diabetes Metab Syndr. 2025 Sep;19(10):103177. doi: 10.1016/j.dsx.2025.103177.
12. Chavez AM, Carrasco Barria R, León-Sanz M. Nutrition support whilst on glucagon-like peptide-1 based therapy. Is it necessary? Curr Opin Clin Nutr Metab Care. 2025 Jul;28(4):351-357. doi: 10.1097/MCO.0000000000001130.
13. Mozaffarian D, Agarwal M, Aggarwal M, Alexander L, Apovian CM, Bindlish S, Bonnet J, Butsch WS, Christensen S, Gianos E, Gulati M, Gupta A, Horn D, Kane RM, Saluja J, Sannidhi D, Stanford FC, Callahan EA. 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. Obesity (Silver Spring). 2025 May 30;33(8):1475–1503. doi: 10.1002/oby.24336. PMID: 40445127; PMCID: PMC12304835.
14. Neeland IJ, Linge J, Birkenfeld AL. Changes in lean body mass with glucagon-like peptide-1-based therapies and mitigation strategies. Diabetes Obes Metab. 2024;26:16-27. doi: 10.1111/dom.15728.
15. Ilias I, Zabuliene L, Rizzo M. GLP-1 receptor agonists in diabetes and weight loss: the double-edged sword of innovation and risks. Front Clin Diabetes Healthc. 2025;5:1530811. doi: 10.3389/fcdhc.2024.1530811.
16. Thomsen RW, Mailhac A, Løhde JB, Pottegård A. Real-world evidence on the utilization, clinical and comparative effectiveness, and adverse effects of newer GLP-1RA-based weight-loss therapies. Diabetes Obes Metab. 2025 Apr;27 Suppl 2:66-88. doi: 10.1111/dom.16364.