Personalised Nutrition Support for Weight Loss Medications (GLP-1 Therapy)

What are GLP-1 medications?

GLP-1 receptor agonists are medications that mimic a hormone called glucagon-like peptide-1, which helps regulate blood sugar and appetite. These medications stimulate insulin release, suppress glucagon, slow stomach emptying, and act on the brain to increase satiety [1,2]. Common agents include Ozempic (semaglutide), Wegovy (semaglutide), Mounjaro (tirzepatide), and Saxenda (liraglutide), which have demonstrated significant benefits for both type 2 diabetes and obesity management [3,4].

How do they help with weight loss?

GLP-1 medications promote weight loss by:

• Suppressing appetite through central nervous system pathways that increase fullness and reduce hunger [2,4].

• Slowing gastric emptying, leading to longer satiety and smaller meal portions [1,3].

• Improving insulin sensitivity and stabilising blood glucose, which can reduce cravings and fat accumulation [2,5].

Clinical trials show average weight reductions of 10–20% in people using GLP-1 receptor agonists compared with placebo [4,6]. These results are strongest when medication is combined with a healthy diet and lifestyle.

Do I need to change my diet if I start a GLP-1 medication?

Yes. Nutrition plays a key role in achieving sustainable results and preventing deficiencies. GLP-1 medications can reduce appetite so much that some people struggle to meet their nutrient needs. Working with a dietitian helps ensure:

• Adequate protein intake (1.2–2.0 g/kg body weight) to preserve lean mass [7,8].

• Sufficient fibre and hydration to reduce constipation and support gut health [9].

• Balanced, nutrient-dense meals to maintain vitamins and minerals as total intake decreases [8,10].

Structured meal planning helps avoid muscle loss and supports long-term metabolic health [7,9].

Can GLP-1 medications help me maintain weight loss?

Medication can assist with maintenance when paired with sustainable habits. Long-term success depends on:

• Consistent meal planning and protein intake to protect lean tissue and metabolism [7,9].

• Regular resistance and aerobic exercise to maintain energy expenditure [11].

• Behavioural strategies that address emotional eating and lifestyle balance [12].

When GLP-1 therapy is discontinued, weight regain is common unless lifestyle changes are well established [6,11].

What side effects should I expect and how can I manage them?

The most common side effects are nausea, constipation, and reduced appetite [3,4]. These are often temporary and can be managed with:

• Small, frequent meals rather than large portions.

• Gradual fibre increases and consistent hydration.

• Eating slowly and avoiding high-fat, greasy foods.

• Monitoring nutrients such as iron, B12, and folate to prevent deficiencies [8,10].

Your dietitian can tailor strategies to your tolerance and nutritional needs.

Will I lose muscle while on GLP-1 medications?

Some lean mass loss is expected during weight reduction, but it can be minimised. Studies show that about 20–35% of total weight loss from GLP-1 therapy may come from lean tissue [7,13]. To counteract this:

• Include enough protein at each meal.

• Engage in resistance training at least twice per week [11].

• Monitor body composition rather than just body weight.

Research emphasises that combining medication with strength-focused nutrition and exercise preserves muscle and improves long-term outcomes [7,13,14].

What if I want to stop medication or switch to maintenance?

Transitioning off GLP-1 therapy should be gradual and supported by your healthcare team. Key strategies include:

• Gradually reducing medication dose while reinforcing nutrition habits.

• Tracking hunger and fullness cues to guide portion control.

• Maintaining regular activity and meal structure to prevent rebound weight gain [6,11].

• Continuing dietitian support to adjust intake and maintain metabolic stability.

Sustainable weight maintenance is possible when healthy behaviours are embedded before medication withdrawal [12,15].

References

1. Müller TD, et al. “Mechanisms of GLP-1 Receptor Agonist–Induced Weight Loss.” Nature Reviews Endocrinology. 2022.

2. Knudsen LB, Lau J. “The Discovery and Development of Liraglutide and Semaglutide.” Frontiers in Endocrinology. 2019.

3. Kushner RF, Calanna S, Davies M, et al. “Clinical Characteristics and Outcomes Associated with GLP-1 Receptor Agonists.” Diabetes, Obesity and Metabolism. 2020.

4. Wilding JPH, et al. “Once-Weekly Semaglutide in Adults with Overweight or Obesity (STEP 1 Trial).” New England Journal of Medicine. 2021.

5. Nauck MA, Meier JJ. “The Incretin Effect in Healthy Individuals and Those with Type 2 Diabetes.” Diabetologia. 2018.

6. Rubino DM, et al. “Effect of Continued Treatment with Semaglutide vs Withdrawal on Weight Maintenance.” JAMA. 2021.

7. Hurren KM, et al. “Preserving Lean Body Mass in Patients Taking GLP-1 for Weight Loss.” Current Developments in Nutrition. 2024.

8. Yabe D, Seino Y. “Defining Optimal Nutrition for GLP-1-Based Therapy.” Diabetes Research and Clinical Practice. 2023.

9. Brown L, et al. “Dietary Fibre and Gut Health During GLP-1 Therapy.” Nutrients. 2022.

10. Madsbad S. “Nutritional Considerations with GLP-1 Receptor Agonists.” Diabetes Therapy. 2023.

11. Wolfe RR. “The Role of Exercise and Protein in Maintaining Muscle During Weight Loss.” American Journal of Clinical Nutrition. 2018.

12. Wadden TA, Tronieri JS, et al. “Lifestyle Modification for Sustained Weight Loss.” Obesity Reviews. 2020.

13. Blundell J, et al. “Body Composition Changes with GLP-1 Agonists.” Diabetes, Obesity and Metabolism. 2022.

14. Andersen A, Lund A, et al. “GLP-1 Receptor Agonists and Muscle Health.” Frontiers in Endocrinology. 2023.

15. Perreault L, et al. “Weight Maintenance After GLP-1 Therapy: Behavioural and Metabolic Strategies.” Obesity Science & Practice. 2024.