GLP-1 Medications

What is GLP-1?

GLP-1 (Glucagon-Like Peptide-1) is a naturally occurring hormone released from your gut after you eat. It plays a key role in:

Regulating blood sugar
Controlling appetite
Slowing digestion
Supporting insulin release
Improving feelings of fullness

GLP-1 is part of the incretin hormone system, which helps your body manage glucose and appetite after meals. The challenge? Natural GLP-1 only lasts about 2 minutes in the bloodstream, which limits its effects.

What Do GLP-1 Medications Do?

GLP-1 medications (called GLP-1 receptor agonists) mimic this hormone — but last much longer in the body. Some newer medications also activate other hormones like GIP, which may enhance fat loss and reduce side effects.

Main Types (2025)

1. GLP-1 receptor agonists (single hormone):

• Liraglutide (Saxenda, Victoza) – daily injection
• Semaglutide (Ozempic, Wegovy) – weekly injection
• Dulaglutide (Trulicity) – weekly injection
• Exenatide (Byetta, Bydureon) – older agents
• Oral semaglutide (Rybelsus) – tablet (diabetes only)

2. Dual agonists (GLP-1 + GIP):

• Tirzepatide (Mounjaro, Zepbound) – currently shows the strongest weight loss results

3. Triple agonists:

• Still emerging and under clinical development

How Do GLP-1 Medications Cause Weight Loss?

These medications don’t “burn fat” — instead, they change how your brain and digestive system regulate hunger and fullness.

They work by:

1. Reducing hunger signals
   → Acting on the brain’s appetite centres so you naturally eat less, without feeling deprived.
2. Increasing fullness
   → Slowing stomach emptying so smaller portions feel satisfying.
3. Lowering food cravings and reward-driven eating
   → Less desire for ultra-processed, high-fat or high-sugar foods.
4. Improving insulin sensitivity
   → Fewer blood sugar dips and rebound cravings.
5. Improving metabolic efficiency over time
   → Reduced visceral fat and fat storage, especially around the abdomen.

Common Side Effects

Most side effects are gastrointestinal and dose-dependent, especially during the early dose increases:

Digestive symptoms:

• Nausea
• Vomiting
• Reflux
• Diarrhoea or constipation
• Bloating
• Early fullness

Nutrition-related concerns:

• Very low appetite → risk of under-eating
• Reduced protein intake → muscle loss risk
• Micronutrient deficiencies if intake drops too low

Other risks:

• Increased gallstone risk with rapid weight loss
• Rare associations with pancreatitis
• May worsen gastroparesis
• Contraindicated in those with medullary thyroid cancer or MEN2

Who Benefits Most?

GLP-1 medications are especially helpful for individuals with:

Type 2 diabetes
Obesity or insulin resistance
Emotional or binge-prone eating patterns
PCOS
Cardiometabolic risk factors
Women in peri-, pre-, or post-menopause

Important Truths About GLP-1 Medications

As a dietitian, this is the part I want people to understand most clearly:

These medications enhance physiology — they do not replace behaviour.
Without nutrition, movement, and lifestyle support, weight regain is common after stopping.
Muscle loss is a real risk if protein intake and resistance training are not prioritised.

What You Should Consider Before Starting

Before starting GLP-1 medication, it’s important to understand:

This is not a short-term fat-burning solution
These medications often require at least 6 months or longer, with slow dose increases, maintenance phases, and careful tapering. Some people need long-term or lifelong therapy to maintain results.

Cost matters
These medications are expensive and usually not covered by medical aid for weight loss alone — budgeting is essential.

Lifestyle changes are non-negotiable
To protect muscle mass, metabolism, and long-term results, focus on:

• High-protein intake
• Plenty of vegetables and fibre
• Adequate hydration
• Regular strength training

Side effects can impact daily life
Constipation, nausea, and reflux are common — and may require dietary and medication adjustments.

Not appropriate for everyone
Especially individuals with a history of eating disorders — this requires specialist oversight.

The Dietitian’s Bottom Line

GLP-1 medications can be powerful, life-changing tools for the right person — particularly when metabolic resistance makes weight loss feel impossible despite best efforts. But they work best when paired with:

Structured nutrition support
Protein-focused eating
Resistance training
Behaviour change strategies
Medical monitoring

Medication alone changes appetite — not habits. Sustainable health comes from addressing both.

If you’re considering GLP-1 therapy and want support with nutrition, muscle preservation, side effects, and long-term success, working with a dietitian alongside your doctor makes all the difference.