1. Why We’re Talking About GLP-1 Now

When your appetite is almost switched off, are you really eating “healthily”?
And do you have a Plan B for the day you stop the injection?

GLP-1 drugs make weight loss easier than ever by turning down hunger signals in the brain. But while the number on the scale is dropping, you also need to know what is disappearing from your body: muscle, bone density, micronutrients or just fat. In this article, we put under the microscope both the promises at the tip of the needle and the metabolic price tag that can come with them.

These are not vitamins; they are medical treatments with potential serious side effects and long-term consequences. Still, if you are determined to use them, we care that you at least understand what you are taking, how it works, and its limits.

Our goal here is neither to glorify nor to demonise GLP-1 medications. Instead, using current scientific evidence, we will walk through:

• How the GLP-1 hormone works,
• In which clinical situations are these drugs actually indicated,
• How much weight loss they tend to produce (and how),
• What happens to muscle mass, gut health, eating behaviour and psychology,
• Why is weight regain so common after stopping,
• and the ethical and societal questions around their use.

In December 2025, the World Health Organisation (WHO) published its first global guideline on GLP-1 and GIP/GLP-1 drugs for adults living with obesity, framing obesity as a chronic, relapsing disease and stressing that these medicines should only be used as one component of a comprehensive treatment programme (diet, activity, behavioural support).

That is exactly why we felt it was time to unpack this topic for you.

2. GLP-1 Basics: What Does This Hormone Actually Do?

GLP-1 (glucagon-like peptide-1) is an incretin hormone made in the gut after you eat. It has a very short life in the blood, but in those minutes it:

• Increases insulin release when glucose is high,
• Reduces glucagon (the hormone that raises blood sugar),
• Slows gastric emptying,
• Sends “you’re full now” signals to the brain.

In simple terms, GLP-1 helps smooth out blood sugar spikes and makes you feel satisfied with less food. It’s one of the body’s natural tools to regulate energy balance.

3. How Do GLP-1 Agonists Work?

GLP-1 receptor agonists (GLP-1 RAs) are drugs designed to mimic this hormone, but with a much longer half-life, hours to days instead of minutes. Modern agents like semaglutide and tirzepatide are given once weekly.

They act on several levels:

• Brain: In the hypothalamus and reward centres, GLP-1 RAs reduce hunger and food-seeking behaviour. Food noise quiets down.
• Stomach and gut: They slow gastric emptying, so food stays in the stomach longer, prolonging fullness and blunting glucose spikes.
• Pancreas: They enhance glucose-dependent insulin secretion and suppress glucagon, improving glycaemic control.

Put together, you spontaneously eat less, feel full sooner and for longer, and overall energy intake falls. That sustained calorie deficit is what drives weight loss, not magic fat burning.

4. GLP-1 Causes Weight Loss, Not Automatic Health

When Are GLP-1 Drugs Actually Indicated?

Guidelines and regulatory agencies currently position GLP-1/GIP-GLP-1 drugs mainly for:

• Type 2 diabetes, particularly with high cardiovascular risk or when other therapies are insufficient.
• Chronic weight management in adults with
  • BMI ≥ 30 kg/m², or
  • BMI ≥ 27 kg/m² plus at least one weight-related condition (e.g. hypertension, dyslipidaemia, obstructive sleep apnoea).

They were not developed as a casual solution for “I’d like to drop 3–4 kilos (around 7–9 lb) before summer” in otherwise metabolically healthy, lean individuals.

Rapid Weight Loss and Lean Mass

Whichever method you use, faster weight loss usually means more lean mass loss alongside fat. GLP-1 drugs are no exception.

Recent reviews suggest that although GLP-1 RAs primarily reduce fat mass, 20–40% of total weight lost can come from lean mass if diet and exercise are not optimised.

That matters because losing muscle:

• Lowers resting metabolic rate,
• May worsen strength and functional capacity,
• Increasing long-term risk of sarcopenic obesity, relatively high fat and low muscle at the same body weight.

So the key question is not just “How much weight did you lose?” but also “What did you lose?”

5. How Much Weight Loss Do GLP-1 Drugs Deliver?

Significant phase 3 trials give us a clear picture of average results.

• Semaglutide 2.4 mg (STEP 1; adults with overweight/obesity, no diabetes):
  ~15% body weight loss at 68 weeks with drug + lifestyle vs ~2–3% with lifestyle
• Liraglutide 3.0 mg (SCALE):
  ~5–8% weight loss over 56 weeks vs ~2–3% with placebo.
• Tirzepatide (SURMOUNT-1; obesity, no diabetes):
  Around 15–22% weight loss at 72 weeks, depending on dose, vs ~3% with placebo.

In people with type 2 diabetes, weight loss is generally slightly smaller (e.g. ~6–10%), but still clinically meaningful.

Body-composition sub-analyses show:

• Large reductions in total and visceral fat,
• But also non-trivial reductions in lean mass, even though the fat:lean ratio overall improves.

So in best-case scenarios, you get:

Less fat, somewhat less muscle, smaller waist, lower cardiometabolic risk, if diet and exercise are handled well.

6. Limits of GLP-1 Use: Side Effects, Risks and Who Should Avoid

Common Gastrointestinal Side Effects

Because GLP-1 RAs slow gastric emptying and act on the gut–brain axis, the most frequent adverse events are gastrointestinal:

• Nausea and vomiting,
• Early satiety,
• Abdominal pain, bloating, reflux-like symptoms,
• Constipation or diarrhoea.

Real-world analyses (e.g. NIH All of Us cohort, >10,000 users) show high rates of GI complaints, especially in the first months and at higher doses.

Gallbladder, Biliary Tract and Pancreas

A large meta-analysis of 76 randomised trials found that GLP-1 RAs are associated with an increased risk of gallbladder and biliary disease, particularly at higher doses, with longer duration and when used specifically for weight loss.

Observational data also raise signals (though not definitive proof) regarding:

• Pancreatitis,
• Gastroparesis or severe delayed gastric emptying,
• Rare but serious intestinal obstruction.

Regulators in several countries now emphasise careful monitoring of GI and biliary symptoms when using GLP-1.

Thyroid and Other Contraindications

For most GLP-1 RAs, product information lists personal or family history of medullary thyroid carcinoma or MEN2 as a contraindication, based largely on rodent data. Patients with prior pancreatitis, severe GI motility disorders, advanced renal or liver disease, or those who are pregnant or breastfeeding usually require individual specialist assessment and often should avoid these drugs.

Mental Health Signals

Regulators have also added warnings about possible mood changes or suicidal ideation, not because a clear causal link has been proven, but because of mixed signals from spontaneous reports and small studies. The current message is “monitor carefully, especially in people with a history of depression or suicidality.”

7. What Happens When You Stop? Weight Regain Explained

This is the uncomfortable part.

In the STEP 1 extension, participants who had lost ~17% of their weight on semaglutide + lifestyle regained about two-thirds of that loss within 1 year after stopping both the drug and structured support.

Key numbers:

• Average weight loss on semaglutide at week 68: –17.3%
• By week 120 (one year off drug): about 11.6 percentage points regained, leaving a net loss of ~5–6%.

Similar patterns are emerging with tirzepatide (Mounjaro): after withdrawal, many participants regain a large proportion of lost weight and see cardiometabolic improvements drift back towards baseline.

A recent pooled analysis of 11 trials (6,370 adults) presented at the European Congress on Obesity suggests that people coming off GLP-1 weight-loss drugs tend to regain most or all of the lost weight within 10–20 months if no structured behavioural support is in place.

Why?

• Appetite hormones (e.g. ghrelin) rise again; satiety signalling drops.
• The brain’s “set point” for body weight pulls you back towards your old range.
• If you lost significant muscle, your new baseline metabolism is lower.

So:

GLP-1s create a strong, medication-driven energy deficit. But unless your behaviours and habits change in that window, the biology waiting underneath is ready to push back the moment you stop.

8. Why Nutrition Is Non-Negotiable During GLP-1 Treatment

Because appetite often drops dramatically, it’s easy to think “I’m barely eating; of course, my diet is fine.” From a dietitian’s lens, this is exactly where the risks start.

Protein: Protecting Muscle

Your protein needs do not fall just because your appetite does. In fact, during rapid weight loss, you probably need a bit more per kilo of body weight, not less.

• Many guidelines suggest ≥1.2–1.5 g/kg/day of protein (roughly 0.55–0.68 g per lb of body weight per day) during active weight loss, adjusted individually for kidney function, age and activity.

Practical strategies when your stomach feels “tiny”:

• Make each eating occasion count: include a meaningful protein source (eggs, yoghurt, tofu, fish, poultry, well-cooked legumes).
• Use soft or liquid protein (e.g., smoothies, yoghurt bowls) if solid foods feel heavy.
• Spread protein across the day rather than loading it all into one large meal.

Micronutrients: Small Things, Big Consequences

Very low total intake and skipped meals increase the risk of deficiencies in:

• Vitamin B12 (especially if you’re also on metformin),
• Iron and folate,
• Vitamin D,
• Omega-3 fatty acids.

Over months, this can show up as fatigue, hair loss, frequent infections, low mood or worsening anaemia. Periodic blood work and targeted supplementation (not random mega-dosing) are important.

Gut Health, Fibre and Hydration

GLP-1 RAs slow gastric emptying and can alter GI motility, which is why constipation and bloating are so common.

You can support your gut by:

• Gradually aiming for 20–30 g/day of fibre (about 0.7–1.1 oz/day), adjusted to tolerance.
• Including prebiotic foods (onions, leeks, oats, legumes, bananas) and probiotic foods (yoghurt, kefir, some fermented products).
• Drinking enough fluids and including electrolytes if nausea reduces intake.

The trick is to increase fibre slowly. If you go from 5 g to 35 g overnight on a slowed gut, you may feel worse, not better.

Drug + Food + Behaviour = Best Outcomes

In all major trials, GLP-1/GIP-GLP-1 drugs were tested on top of lifestyle intervention, not instead of it. Participants received diet counselling, activity goals and regular follow-up.

The most sustainable results appear when three elements are in place:

1. Medication (when indicated),
2. A structured nutrition plan (with enough protein, fibre and micronutrients),
3. Behavioural change support (coaching, CBT, group programmes, etc.).

9. Behavioural Eating and Psychology: What the Drug Doesn’t Fix

GLP-1 drugs can quiet physical hunger and constant food thoughts, but they do not automatically heal:

• Emotional eating,
• Stress-driven snacking,
• Binge-restrict cycles,
• Body image issues.

Emerging research suggests GLP-1 RAs may modestly reduce emotional and uncontrolled eating scores in some individuals, but the effect is variable and often wanes over time without psychological support.

If your main struggle has always been how you use food to cope, you will likely still need:

• Psychotherapy or counselling,
• Skills for emotion regulation,
• Work on self-compassion and body image,
• Structured relapse-prevention strategies.

Medication can create space to practise new behaviours, but it doesn’t do the practising for you.

10. Exercise: Your Best Defence Against Muscle Loss

On GLP-1, many people report, “I just don’t feel like moving; I’m tired, and I’m already losing weight, so why bother?” From a long-term health standpoint, this is risky.

Current reviews highlight that GLP-1 RA-induced weight loss can disproportionately affect lean mass in older adults or those with low activity, increasing the risk of frailty and falls.

A realistic minimum framework (to be individualised medically):

• 2–3 days/week of resistance training, covering major muscle groups (weights, machines, resistance bands, or body-weight circuits).
• Daily movement (walking, light cycling, or any low-impact activity that fits your life) slowly progressing towards 7–8k+ steps/day if feasible.

Think of exercise here not as “burning extra calories” (the drug is already doing that), but as protecting your muscles, bones and independence.

11. Ethics, Access and the Social Context

GLP-1 therapies have changed how the world talks about obesity: from a “willpower issue” to a treatable chronic disease.

At the same time:

• WHO warns that fewer than 10% of eligible people globally are likely to access these drugs by 2030, due to cost and supply limits.
• In some health systems, cosmetic or off-label use has contributed to shortages, making it harder for people with diabetes or severe obesity to obtain medication.
• Social media sometimes frames GLP-1 jabs as a lifestyle accessory rather than a serious medical treatment, fuelling unrealistic expectations and stigma in both directions (“you’re cheating” vs “why aren’t you on the jab yet?”).

This raises questions we can’t ignore:

• Who gets access first, those with the greatest medical need or those with the greatest purchasing power?
• Are we investing enough in food systems, urban design and prevention, or only in expensive downstream treatments?
• What message are we sending to young people about body image and quick fixes?

12. Life After GLP-1: Building a Plan B (and C)

If you’re starting a GLP-1 or already on one, it’s worth sitting down and asking:

“If my dose is reduced or stopped in 6–24 months, what habits and systems will be there to catch me?”

Key pillars of a post-GLP-1 maintenance plan:

Protein- and fibre-centred meals

• Keep each meal structured around a protein source + vegetables + a smart carb (whole grains, legumes, fruit).
• Keep ultra-processed, hyper-palatable foods in check; they can rapidly “out-talk” your internal satiety signals once the drug is gone.

Resistance training is a non-negotiable

• Think of it like brushing your teeth for your muscles and bones – not optional self-improvement, but basic maintenance.

Sleep and stress routines

• 7–9 hours of consistent sleep,
• basic stress-management tools (breathing, journaling, scheduling in enjoyable non-food rewards),
• boundaries around work and screens.

Behavioural support

• A dietitian, psychologist, coach or group programme to guide you through dose reductions and off-ramps.

Data from the STEP programme and other cohorts consistently tell us: without ongoing support, weight and cardiometabolic risk markers drift back after stopping treatment.

GLP-1 isn’t a reset button that permanently rewires your biology. It is more like a window of opportunity during which changing your environment, skills, and routines becomes easier if you use that window intentionally.

13. Take-Home Message

• GLP-1 and GIP/GLP-1 drugs are among the most effective medical tools we’ve ever had for obesity and type 2 diabetes, with average weight losses of 10–20% and substantial cardiometabolic benefits in appropriately selected patients.
• They also come with real risks: GI side effects, gallbladder and biliary issues, potential lean-mass loss, cost and access problems, and the high likelihood of weight regain when treatment stops unless habits change.
• From a nutrition and lifestyle perspective, the priority is not just “getting lighter” but staying strong, nourished and functional: protecting muscle, supporting gut health, and building sustainable eating and movement patterns.

Our stance is simple:

We don’t fully “approve” or “disapprove” of GLP-1 drugs. We see them as powerful tools that should be used carefully, for the right people, with full informed consent and always, always as part of a bigger plan that includes food, movement and mindset.

If you and your medical team decide that GLP-1 therapy is right for you, our wish is that you use it with your eyes open: understanding both its possibilities and its limits, and giving your body the nutrition, movement, and support it deserves along the way.

Important
This article is for general information only and does not replace medical advice. GLP-1 and GIP/GLP-1 drugs are prescription medications. Decisions about starting, changing, or stopping them must be made with your doctor or specialist team, who know your full medical history.

References

1. Drucker, D. J. (2024). Efficacy and safety of GLP-1 medicines for type 2 diabetes and obesity. Diabetes Care, 47(11), 1873–1888.
2. Grunvald, E., Shah, R., Hernaez, R., Chandar, A. K., & Pickett-Blakely, O. (2022). AGA clinical practice guideline on pharmacological interventions for adults with obesity. Gastroenterology, 163(5), 1199–1227.
3. World Health Organization. (2025). WHO guideline on the use of glucagon-like peptide-1 (GLP-1) therapies for the treatment of obesity in adults. Geneva: WHO.
4. Wilding, J. P. H., Batterham, R. L., Calanna, S., et al. (2021). Once-weekly semaglutide in adults with overweight or obesity. New England Journal of Medicine, 384(11), 989–1002.
5. Wadden, T. A., et al. (2015). A randomized, controlled trial of 3.0 mg of liraglutide in weight management. New England Journal of Medicine, 373, 11–22.
6. Jastreboff, A. M., et al. (2022). Tirzepatide once weekly for the treatment of obesity. New England Journal of Medicine, 387(3), 205–216.
7. Wilding, J. P. H., Batterham, R. L., Davies, M., 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.
8. Wilding, J. P. H., Batterham, R. L., Calanna, S., et al. (2021). Impact of semaglutide on body composition in adults with overweight or obesity: Exploratory analysis of the STEP 1 study. Journal of the Endocrine Society, 5(Suppl. 1), A16–A17.
9. Ceasovschih, A., Asaftei, A., Lupo, M. G., et al. (2025). Glucagon-like peptide-1 receptor agonists and muscle mass effects. Pharmacological Research, 220, 107927.
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11. He, L., Wang, J., Ping, F., et al. (2022). Association of glucagon-like peptide-1 receptor agonist use with risk of gallbladder and biliary diseases: A systematic review and meta-analysis of randomized clinical trials. JAMA Internal Medicine, 182(5), 513–519.
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Frequently Asked Questions (FAQ)

What are GLP-1 weight loss drugs?

GLP-1 weight loss drugs are injectable medications that mimic the glucagon-like peptide-1 (GLP-1) hormone, which regulates appetite and blood sugar levels. They are primarily prescribed to help manage obesity and type 2 diabetes by reducing hunger and improving insulin response.

How do GLP-1 drugs help with weight loss?

GLP-1 drugs work by slowing gastric emptying, reducing hunger signals in the brain, and enhancing the release of insulin when blood sugar is high. This leads to lower food intake, improved blood sugar control, and sustained weight loss.

Who is eligible to use GLP-1 weight loss drugs?

Some GLP-1 and GIP/GLP-1 medications have been approved in many countries for chronic weight management in adults with:

• a BMI of 30 kg/m² or higher, or
• a BMI of 27 kg/m² or higher plus at least one weight-related condition (such as high blood pressure, type 2 diabetes, or high cholesterol).

Exact rules vary by country and by medication, so your healthcare provider will assess your individual eligibility.

What are the most common side effects of GLP-1 drugs?

The most common side effects include nausea, vomiting, diarrhoea, constipation, and abdominal discomfort. These symptoms often improve over time as the body adjusts to the medication.

Are there any serious risks associated with GLP-1 weight loss drugs?

While generally safe when prescribed and monitored by a doctor, GLP-1 drugs can increase the risk of gallbladder disease and pancreatitis in some patients. It is important to seek medical attention if you experience severe abdominal pain or other concerning symptoms.

How are GLP-1 drugs administered?

These medications are typically given as subcutaneous injections into fatty tissue, usually in the belly (abdomen), thigh, or upper arm. Your healthcare provider will show you exactly where and how to inject them.

Can GLP-1 drugs be used with other medications?

Yes, GLP-1 drugs can be prescribed alongside other medications, but it is essential to inform your healthcare provider about all medications you are taking to avoid potential interactions and ensure safety.

What happens if I stop taking GLP-1 weight loss drugs?

Stopping GLP-1 drugs may lead to weight regain because the medication suppresses appetite and regulates blood sugar. To maintain benefits, it is important to continue dietary changes, exercise, and follow your healthcare provider's advice.

Are GLP-1 drugs safe during pregnancy?

People of childbearing potential are usually advised to use reliable contraception and, if planning a pregnancy, to discuss stopping the medication well in advance with their doctor.

Where can I get GLP-1 weight loss drugs?

GLP-1 drugs require a prescription from a healthcare provider who can assess your health conditions, prescribe the appropriate medication, and provide guidance on usage and monitoring for effectiveness and safety. They are not cosmetic treatments and should be used as part of a broader long-term plan that also includes nutrition, physical activity, and behavioural support.