Understanding weight loss medications

8 Oct

How It Works, Where It Struggles & Why Nutrition Matters

A New Era in Weight Loss?

Medications such as Ozempic® (semaglutide), Wegovy® (semaglutide), Victoza® (liraglutide), and Mounjaro® (tirzepatide) were originally developed to support type 2 diabetes management. Today, they are increasingly prescribed for weight loss and have become household names.

But what exactly are these drugs doing in the body? Who qualifies for them? Why are people struggling both during and after use? And where does nutrition fit in?

Who Is Eligible for GLP-1 Medication?

On the NHS, eligibility usually requires:

· A Body Mass Index (BMI) of 40 or above (or 37.5 or above for some ethnic backgrounds), plus at least four of the following five conditions:
• Type 2 diabetes
• High blood pressure
• High cholesterol
• Heart disease (cardiovascular disease)
• Obstructive sleep apnoea

A GP referral to a specialist weight management service is also needed as part of a comprehensive NHS care plan.

Privately, eligibility is often assessed through an online questionnaire with a healthcare professional. Prescriptions typically require a BMI of 30 or higher (or 27 with a weight-related condition). Prices vary by medication and dosage, but most people can expect to pay £150–£300 or more per month.

Contraindications include:

· History of certain thyroid cancers

· Pancreatitis

· Renal impairment

· Hepatic impairment

· Ketoacidosis

· Severe gastroparesis

· Pregnancy

Caution is exercised in the elderly, women of childbearing age or breastfeeding, those with severe heart failure, thyroid disease, retinopathy or gallbladder issues.

The Scale of Use

· By 2024, ~4% of Americans were taking GLP-1 medications for overweight, obesity, or type 2 diabetes.

· An estimated 12% of Americans have tried a GLP-1, even if affordability was an issue.

· In the UK, reports suggest around 1.5 million people are currently taking them.

Concerns have been raised, particularly in the UK, about many individuals obtaining prescriptions from private online clinics rather than after an in-person medical consultation. In such cases, it is possible to exaggerate weight or co-morbidities to obtain approval for these powerful medications.

What GLP-1 Normally Does in the Body

GLP-1 (glucagon-like peptide-1) is a hormone naturally produced in the gut after eating. It plays a vital role in:

· Stimulating insulin secretion (for glucose control)

· Sending satiety signals (helping you feel full)

· Slowing gastric emptying (keeping you fuller for longer)

· Suppressing glucagon (reducing blood sugar spikes)

Think of GLP-1 as part of your body’s metabolic “brake system”, regulating hunger and glucose balance after meals.

How GLP-1 Medications Work

GLP-1 medications mimic this natural hormone, though each drug differs in ingredient, strength, frequency of dosing, and approval for conditions like diabetes versus obesity.

· Semaglutide (Ozempic/Wegovy): long-acting GLP-1 receptor agonist

· Liraglutide (Victoza/Saxenda): shorter-acting, daily injection

· Tirzepatide (Mounjaro): a dual agonist that mimics both GLP-1 and GIP

In essence, these drugs:

· Suppress appetite and cravings

· Reduce food intake

· Slow gastric emptying

· Lower post-meal blood glucose

· Often produce dramatic weight loss, even without lifestyle changes

But, they also bypass the natural hunger/satiety feedback loops, and that is where challenges begin.

Where People Struggle

Across clinical practice, online forums, and patient reports, consistent challenges emerge:

· Digestive distress: nausea, vomiting, constipation, diarrhoea, bloating, dyspepsia, reflux, burping, diarrhoea, gallbladder disorders

· Headaches, dizziness, drowsiness, fatigue and dehydration

· Mood issues: anxiety, insomnia, low mood

· Hair loss or alopecia, dry mouth, altered taste, excessive sweating

Skin reactions including rash, angioedema, cutaneous amyloidosis (liraglutide), urticaria, and pruritus.
Heart issues including Excessively fast heartbeat or interference with hearts electric impulses
Acute pancreatitis or renal impairment

· Nutrient deficiencies – due to reduced appetite and consumption

· Loss of muscle mass (especially with inadequate protein intake)

· Fear of weight regain after stopping

· Disordered eating patterns or loss of food enjoyment

In addition, fast weight loss increases susceptibility of vomiting and sagging skin.

These are not just “side effects.” Many are consequences of the mechanism itself.

The Muscle Mass Problem

Muscle is far more than strength or appearance; it’s one of the body’s most important metabolic organs. Around 70–80% of the glucose we eat is stored in skeletal muscle, making it crucial for blood sugar balance and easing the load on insulin.

Because muscle is metabolically active, it also burns calories even at rest, while protecting against frailty by supporting mobility, balance, and resilience as we age. This is why losing muscle during rapid weight loss - as can happen with GLP-1 medications - is concerning: it means losing part of your body’s metabolic “engine,” which can make long-term weight maintenance and healthy ageing more difficult.

Research shows that 15-40% of the weight lost on GLP-1 drugs is actually lean mass, not just fat. That matters, because “lean mass” isn’t spare tissue - it includes muscle, bone, and organ reserves that are vital for health and recovery.

To complicate things further, many clinical trials report results in broad terms like “lean mass” or “fat-free mass,” which can obscure just how much functional muscle is being lost. The issue is serious enough that new drug trials are already investigating ways to protect muscle while people are on these medications.

My Professional View

Here’s where I stand at the moment:

1. GLP-1 medications can be very effective for some people, but the benefits are often presented without the full picture of risks and side effects.

2. I completely understand why people use them - the promise of quick, noticeable weight loss can feel motivating.

3. Personally, I see weight loss as only part of the story. Health, energy, strength, and resilience are the deeper goals worth aiming for.

4. At a population level, I don’t believe these medications alone will “solve” obesity - true change comes from addressing lifestyle, environment, and support.

5. Long-term safety is still uncertain, and future research may change how these drugs are viewed.

That said, I do not dismiss them. If you’re taking a GLP-1, or considering it, you deserve support. With the right nutrition and lifestyle strategies, it’s possible to reduce side effects, protect your health, and make your journey with these medications safer and more sustainable.

Where Nutrition Can Help

Medications like Ozempic may alter hormone signalling, but they do not replace your body’s need for nourishment, structure, and metabolic stability.

In practice, many of my clients on GLP-1s find their appetite almost disappears - sometimes eating just one small meal a day. While this feels like part of the drug’s “magic,” it also means every bite really counts. I help clients understand exactly what foods to focus on to protect muscle, energy, and long-term health.

As a Nutritional Therapist with a functional medicine approach, I support clients imbalanced body systems with:

· Blood sugar balance to reduce energy dips and mood crashes

· Digestive support for nausea, bloating, or constipation

· Protein and micronutrient replenishment for muscle, skin, and hair health

· Hydration and electrolyte support for energy and gut movement

· Emotional nourishment and structured eating to prevent food fear or binge cycles

Nutrition support isn’t just about what you eat, but why. Many people use food for comfort or stress relief. Addressing this while on the medication means it’s less likely to sabotage progress when coming off. Alongside that, lifestyle strategies such as resistance exercise and targeted nutrition can help preserve and rebuild muscle - protecting your metabolic “engine” both during treatment and afterwards.

There is no one-size-fits-all solution. This is exactly where bespoke nutritional therapy shines.

Coming Off GLP-1s. What Next?

One of the biggest fears people have is: “Will the weight come back?”

The truth is, once the medication is reduced or stopped, hunger hormones often surge. Many describe it as “the food noise comes roaring back”, constant thoughts about food, stronger cravings, and a louder inner pull towards eating. Alongside this, energy and mood can dip, and weight may begin to rebound if the body isn’t supported.

But this doesn’t have to be overwhelming. With the right nutrition, movement, and mindset, it’s possible to manage hunger hormones, protect muscle, and stabilise metabolism. Functional nutrition provides tools and strategies to help people not just transition off the medication more smoothly, but also maintain results and feel confident in life beyond it.

Looking Ahead

If you’re on a GLP-1 medication, or considering it, you don’t have to navigate it alone. My role is to support you in a practical, non-judgemental way, helping you protect your health, feel confident with food, and maintain results that last.

While you’re taking the medication, I can guide you on what to eat when appetite is low, making sure every bite counts for energy, digestion, and muscle health. When it’s time to come off, I’ll help you manage hunger hormones, quiet the “food noise,” and build a sustainable way of eating that supports long-term wellbeing.

You’ll also find encouragement and resources in my community, and I offer one-to-one calls for more personalised support.

Very soon, I’ll be releasing a free guide:

“Supporting Your Body on (and after) Ozempic – A Functional Nutrition Toolkit”, packed with practical strategies for nourishment, stability, and strength at every stage of your journey.

If you’d like to talk to me about the option of more personalised support, book a free, zero obligation call.

Kate Black