It's hard to open a newspaper, scroll through social media or have a conversation about weight management without hearing the words Ozempic, Wegovy or Mounjaro. What started as medications for type 2 diabetes have become the buzziest topic in health, transforming the way we think about obesity treatment and offering hope to millions of people who have struggled with their weight for years.
An estimated 2 to 2.5 million adults in the UK have already used, or are currently using, a GLP-1 medication, with millions more considering them, particularly as new oral versions begin to reach the market, making treatment more accessible than ever.
The excitement is understandable. These medications work. They have produced levels of weight loss that, until recently, were largely only seen after bariatric surgery. But there is another side to the story.
As a dietitian working with people before, during and after GLP-1 therapy, I've seen just how life-changing these medications can be. I've also seen the challenges that come with them: from nausea and constipation to muscle loss, nutritional deficiencies when the medications aren't supported with the right lifestyle changes, and the anxiety many people experience around weight regain when it comes time to stop.
So if you're thinking about taking a GLP-1, here's what you need to know before you start.
First things first: what is a GLP-1?
GLP-1 stands for glucagon-like peptide-1, a hormone your body naturally produces after eating. One of its many jobs is to communicate to the brain that you've eaten enough. It slows the rate at which food leaves your stomach, improves blood glucose regulation and increases feelings of fullness while reducing hunger.
The medications simply amplify this natural system. By mimicking GLP-1 and remaining active in the body for much longer than the hormone your body produces on its own, they help people eat less without feeling like they are constantly battling hunger.
Do they really work?
In short, yes.
GLP-1 medications are the most effective weight-loss medications we've ever had. In the STEP 1 trial, people taking semaglutide lost an average of 17.3% of their body weight over 68 weeks. Other studies have demonstrated weight losses approaching 20%, while newer medications such as retatrutide have reported weight loss of up to 30% in phase 3 clinical trials — results that begin to approach, and in some cases rival, bariatric surgery.
For many people, the most profound benefit isn't simply the number on the scales. It's the reduction in food noise. That constant mental chatter around food quietens, making healthier choices feel less like a daily battle.
The good, the bad and the ugly
The good news is that these medications work remarkably well when prescribed to the right person and used alongside appropriate lifestyle support.
The downside is that they are not free from side effects. Nausea, constipation, vomiting and reflux are common, particularly during dose escalation. Rapid weight loss may also contribute to muscle loss, gallstones and changes in appearance that have become known as "Ozempic face" or "Ozempic butt". For most people, though, the side effects aren't enough to deter their use. More serious complications, such as pancreatitis, remain rare but are recognised.
In my clinical practice, I also find that many side effects become worse when people aren't eating enough protein or fibre, are dehydrated or have increased their dose too quickly.
The final challenge is one we don't talk about enough: what happens when you stop.
These medications are designed for long-term use because obesity is a chronic condition. Yet real-world studies show that many people discontinue treatment within the first year, whether because of cost, side effects, supply issues or personal choice. Unfortunately, weight regain is common if there is no plan in place. Losing weight and keeping it off are two very different challenges, requiring different skills, strategies and support.
Before you start, ask yourself...
Before beginning treatment, I encourage every client to ask themselves a few simple questions:
- Do I actually need this medication?
- Am I prepared for the potential side effects?
- Am I obtaining it from a reputable provider?
- What is my long-term plan once I reach my goal?
- Am I willing to rebuild my eating habits while the medication is working?
Those questions often determine long-term success far more than the medication itself.
Make the medication work for you, not instead of you
GLP-1 medications create an incredible opportunity, but they are exactly that: an opportunity. Use the period of reduced appetite to protect muscle with adequate protein (a minimum of 70g per day), aim for around 30g of fibre each day, stay well hydrated, strength train regularly and rebuild your relationship with food. Think of this as the time to create habits that will still be there long after the medication has gone.
A multivitamin, protein powder or fibre supplement may help fill nutritional gaps while appetite is reduced, but they should support, not replace, a balanced diet.
Life after GLP-1
The finish line isn't reaching your goal weight. The finish line is maintaining it.
As appetite returns, your biology begins encouraging you to regain weight. Protecting muscle, prioritising protein and fibre, moving consistently, sleeping well and designing an environment that supports healthy habits all become even more important. Weight maintenance isn't about having more willpower. It's about having a better plan, and that is exactly why I wrote my book. I saw a significant gap in both the conversation around weight maintenance and the resources available for it. My vision for Life After Weight Loss Medication is that it becomes a weight maintenance toolkit.
Looking ahead
The world of GLP-1s is evolving rapidly. Newer medications are delivering even greater weight loss, oral formulations are making treatment more accessible and combination therapies are already being investigated. The future of obesity treatment is genuinely exciting.
But regardless of how powerful these medications become, one principle is unlikely to change.
Medication may help you lose the weight. The habits you build while taking it are what help you keep it off.
