On Ozempic, Mounjaro, or Wegovy in Your 40s? Here’s What the Research Actually Says About Making It Work Long-Term

If you’re in your 40s and the weight is creeping on differently than it used to, despite feeling as if you are doing everythig ‘right’… you’re not imagining it. Perimenopause changes how your body handles weight, and it’s a big part of why so many women are now turning to GLP-1 medications like Wegovy, Mounjaro, and Saxenda.

You’ve probably seen the headlines. What you might not have seen is the research on what actually helps these medications work well, safely, and for the long term, especially for women in midlife.

I recently wrote a scientific review to pull together the latest evidence on exactly that.¹ Here’s what it means for you, in plain English.

What are GLP-1s medications?

GLP-1 medications (the “GLP-1s”) work by copying a hormone your gut already makes naturally after you eat. This hormone helps you feel full, slows down digestion, and helps keep your blood sugar steady. Originally developed for type 2 diabetes, they’ve turned out to be very effective for weight loss too, for many people, producing results similar to what used to only be possible with weight-loss surgery (bariatric).

And you’re far from alone if you are considering them. Research estimates that hundreds of thousands of UK adults have used a GLP-1 purely for weight loss in the past year, with millions more interested, and women in midlife are one of the biggest groups doing exactly that.¹

They work. But here’s the part that doesn’t get talked about enough.

GLP-1s can lead to significant weight loss, often more than diet and exercise alone. But the research is clear on a few things that matter, especially for women over 40:

Weight regain is common. Most people regain a meaningful amount of the weight they lost within a year or so of stopping the medication, and this can continue over several years.¹ This isn’t a personal failure, it’s how the body responds when appetite-suppressing support is removed. It’s one of the strongest arguments for building sustainable habits alongside the medication, not just relying on it alone.

You can lose muscle, not just fat. This one matters a lot in your 40s. A meaningful chunk of the weight lost on these medications can come from muscle rather than fat, and as muscle is already something we naturally start to lose with age this part is essential to be aware of… Research comparing this to the ageing process found it can be comparable to a decade’s worth of natural muscle loss, compressed into a much shorter time.¹ Since muscle helps keep your metabolism, strength, and blood sugar stable, protecting it matters, especially heading into your 50s and beyond.

Nutrient gaps are common. Because these medications reduce appetite so effectively, it’s easy to accidentally under eat, not just calories, but key nutrients too. Studies have found people using GLP-1s often fall short on fibre, calcium, iron, magnesium, potassium, and vitamins A, C, D and E.¹ If you’ve been feeling unusually tired, noticing hair thinning, or your skin feels off, this could be part of the picture.

Tummy troubles are the most common side effect. Nausea, bloating, constipation, and other digestive symptoms affect the large majority of people using these medications, especially in the first few months or when the dose increases.¹ For most people this settles over time, but it’s genuinely one of the top reasons people stop treatment altogether.

Other medications can be affected. Because these drugs slow down digestion, they can also affect how well other medications are absorbed, including the contraceptive pill and hormone replacement therapy (HRT). If you’re taking either of these, it’s worth raising directly with your prescriber.

Why this matters even more in perimenopause

Here’s the thing nobody quite spells out – perimenopause is already a time when your body is naturally losing muscle and bone density, and your metabolism is shifting. Adding a medication that can accelerate muscle loss, on top of what’s already happening hormonally, is exactly why nutrition and lifestyle support isn’t a “nice to have” alongside these medications, it’s genuinely protective for your long-term health.

This review made a clear point most of the current guidance around these medications focuses almost entirely on the weight-loss number, and not nearly enough on diet quality, nutrient adequacy, or protecting muscle and bone.¹ That gap is exactly where working with a nutrition professional can make a real difference.

What actually helps – The practical takeaways

Based on the current research, here’s what tends to make the biggest difference:

Prioritise protein at every meal. Aim for roughly 80–120g of protein a day, spread across smaller, more frequent meals if your appetite is low. This is one of the most important things you can do to protect muscle mass while losing weight.¹

Don’t skip strength training. Around three sessions of resistance training a week, alongside regular walking or other movement, is strongly linked to preserving muscle (and even bone) while on these medications.¹ This matters more in your 40s and beyond, not less.

Choose nutrient-dense foods over “just eating less.” Small, regular meals built around lean protein, vegetables, fruit, nuts, seeds and legumes will serve you far better than simply eating less of everything. Interestingly, foods like avocado, eggs, nuts, seeds and legumes may even naturally support your body’s own levels of this appetite suppressing hormone.¹

Have a nausea toolkit ready. Ginger tea, peppermint tea, and eating smaller, more frequent meals (rather than skipping meals and then eating a big one) can help manage the most common side effects. Foods with higher water content, like fruit and vegetables, can also help keep things moving if constipation is an issue.¹

Consider your micronutrients. Given how common nutrient shortfalls are, it may be worth discussing supplementation with a practitioner, particularly for fibre, calcium, iron, magnesium, potassium and key vitamins.

Protect your sleep and manage stress. This isn’t just “self-care” advice, poor sleep and high stress genuinely work against weight loss by affecting blood sugar and increasing cravings, through their effects on stress hormones like cortisol.¹

Get proper support, not just a prescription. The research is clear about this; most people using these medications are not currently getting the nutritional monitoring and support that would help them get the best, safest, and most sustainable results.¹ If you’re on a GLP-1 (or considering one), working with a registered nutrition professional alongside your prescriber isn’t an extra,  it’s genuinely part of doing this well.

The bottom line

GLP-1 medications are a real, effective tool, but they work best as part of a bigger picture, not as a standalone fix. In your 40s, when muscle and bone are already more vulnerable and hormones are shifting, that bigger picture matters more than ever. Prioritising protein, strength training, and proper nutritional support alongside the medication is what the current evidence points to as the difference between short-term weight loss and results that actually last.

If you’re using a GLP-1, or considering one, and want to talk through whether a structured approach is right for you, I offer a paid discovery call for £145 (UK and Ireland). We’ll look at your current intake, your goals, and where the gaps are, so that you can not just losing weight, but lose it well. It’s a chance to discuss your situation, check suitability, and see whether my 3-month weight loss programme is the right fit before committing to anything further.

This post is a plain-language summary of a peer-reviewed narrative review: Brady, G., Steele, C., Grundel, C., & Barrow, M. (2026). “Supporting Clients on GLP-1 Therapy: Evidence-Based Nutritional and Lifestyle Strategies for Weight Management.” Nutrition Evidence Database (NED) Journal, March 2026. This article is for general education and isn’t a substitute for medical advice, please speak with your GP, prescriber, or a registered nutrition professional before starting or stopping any medication.