Semaglutide is the active ingredient in diabetes drug Ozempic and weight-loss drug Wegovy - both of which have made headlines for their effectiveness helping people lose weight. But their widespread use may make diet and lifestyle medicine more needed than ever. Hatty Willmoth writes.

Ozempic, Wegovy and other weight-loss medications are arguably the biggest health story of 2023: drugs that might solve the obesity crisis now available on the NHS.

Semaglutide, the active ingredient in Ozempic and Wegovy, is apparently ubiquitous in the celebrity world and apparently lifesaving for those for whom it has been developed.

With Mounjaro on the way in 2024 – a similar drug, using tirzepatide, that’s supposedly even more powerful – a revolution seems underway, one where obesity has been conquered by pharmaceuticals once and for all.

But it might not be that simple. And, as these drugs become more widespread, nutrition and lifestyle specialists may be more needed than ever.

What is semaglutide?

Semaglutide is a glucagon-like peptide-1 receptor agonist (GLP-1 agonist): that’s a very complicated name for a very clever type of drug.

GLP-1 agonists mimic a fullness hormone called GLP-1 that the body produces naturally, tricking the body into feeling fuller than usual.

Semaglutide also slows down the process of digestion, so food stays in the stomach for longer and sugar enters the bloodstream more gradually.

With blood sugar fluctuations dampened, the body does not need to produce big spikes of insulin, but semaglutide encourages insulin production so it helps manage blood sugar levels this way too.

Many people on semaglutide have also reported reacting to foods differently before they eat it, feeling apathetic to or revolted by foods they might usually crave.

What does semaglutide do?

There is an ever-growing collection of GLP-1 agonists, such as tirzepatide, liraglutide and dulaglutide – but semaglutide has dominated the headlines in the form of Ozempic and Wegovy.

These drugs are manufactured exclusively by Danish pharmaceutical company Novo Nordisk and given to patients as weekly injections – and soon maybe pills.

Ozempic is intended to treat type 2 diabetes, and Wegovy is a higher dose of semaglutide developed for weight loss.

However, both have mainly received attention for their potential to help people lose large amounts of weight very quickly.

Who is semaglutide for?

For those familiar with metabolic diseases, it should come as no surprise that better blood sugar control and more effective insulin production would be beneficial to those with type 2 diabetes.

That’s what Ozempic – the first semaglutide drug – was developed to treat. But scientific trials of Ozempic showed that participants lost weight too.

A higher dose of semaglutide was developed (becoming the drug Wegovy) specifically to help people with obesity lose weight.

Ozempic and Wegovy are therefore just different doses of the same thing – semaglutide – intended to treat different things: type 2 diabetes and obesity, respectively.

And they really work. Extensive research has shown in many countries, among thousands of participants in randomised controlled trials, that semaglutide is more effective than placebos.

During a 2021 trial of a higher dose of semaglutide – 2.4mg, like Wegovy – on 1,961 adults with BMIs of 30 or more for over a year, those taking semaglutide lost an average of 15% of their body weight, compared to the placebo group which lost an average of 2.4%.

What it's known for: semaglutide for the super-rich

But semaglutide became the centre of swelling media attention, not for its effectiveness tackling diabetes or obesity, but for being Hollywood’s worst-kept secret, according to a Variety article from September 2022.

Celebrities and wealthy LA socialites – from Elon Musk to Robbie Williams and, according to rumour, the Kardashians – have turned to Ozempic off-label, i.e. for a purpose other than its intended use, using a diabetes drug for slimming.

In a statement for this article, Novo Nordisk said: “Prescription-only medicines should be used in line with their approved indication. …[We are] doing our utmost to discourage the off-label use of our medicines.”

Off-label demand for semaglutide

But it’s not just the ultra-rich who have got their hands on semaglutide without a diabetes diagnosis or significant weight to lose.

A recent Channel 4 documentary showcased how easy it is to obtain semaglutide privately, with an online application filled in with false information or face-to-face in clinic.

One doctor offered to inject the undercover presenter at her first consultation, despite not being eligible for it.

There is so much demand for semaglutide that there have been global shortages since it first became available on the market – exacerbating supply chain issues from its manufacturer, Novo Nordisk.

In July, to mitigate these challenges, Novo Nordisk issued a directive to health professionals in the UK to only prescribe semaglutide to those patients who are eligible for it, and to be restrained with new prescriptions, to prevent those who genuinely relied on the drugs for their health from being unable to acquire it.

In a statement for this article, they also said they were “acutely aware of the uncertainty and concern” that shortages are causing, and of “the disruption patients and healthcare professionals are experiencing” and are “taking steps so that everyone that relies on our medicines can continue to access them”.

Using semaglutide to lose a few kilos

But it’s still really easy to acquire these drugs if you want to, and that has caused some concern that it might be misused – including for Dr Natascha van Zyl, a health psychologist and lifestyle medicine specialist.

She is concerned that people with a history of disordered eating may wish to abuse these drugs, and worries that others are “getting confused” about semaglutide.

“You’ve got celebrities who are not overweight or obese advertising this,” she says, “and the public message is that, if I’m a little bit overweight, I can get an injection.

“We’re seeing people who want to shed a few pounds wanting to use these drugs as well, and I do get the appeal. But… what is your long-term game plan?

“Is it to get into that sexy dress or that fancy tuxedo, or is it sustainable lifestyle change, in which case we need to have a different conversation.”

Side-effects and risks of semaglutide

When semaglutide research was presented to the scientific community, a whole conference reacted in a standing ovation, whooping and cheering wildly.

But semaglutide is not an easy drug to be on. Van Zyl says: “People want the quick fix. That’s appealing, of course it is. But what I think is missing from the conversation is the side effects.”

These are common and unpleasant; 44% of people on semaglutide experience nausea, for example, according to a 2022 analysis.

Gut issues are especially common too (present in approximately 64% of cases), and many people on semaglutide experience some combination of constipation (24%), diarrhoea (30%), vomiting (25%), flatulence, fatigue, and abdominal pain.

These symptoms tend to flare up after each injection and wear off over the course of the week.

But there can be also more severe side effects, such as damage to the pancreas, eyes, gallbladder and kidneys, as well as dangerously low blood sugar levels, acid reflux and hair loss.

Because people tend to eat much less food on semaglutide, there’s also a risk of nutrient deficiencies, and this can lead to a wide range of symptoms too.

“If you’re losing weight rapidly,” explains Van Zyl, “you’ve obviously got [the potential for nutritional deficiencies].

“If you’re still having junk food and hyper-processed foods, you might be losing weight, but you’re losing nutrition. So that’s important.

“If you’re an older person, [there’s a risk of losing] bone density, muscle wasting – and it’s difficult to get that back.”

“We also know that semaglutide works on pleasure pathways. What’s the impact on mental health? … This is a new area of research, and there’s a lot we need to learn, but that concerns me.”

There have also been reports of stomach paralysis and frequent vomiting even after coming off semaglutide.

And animal studies found an association with thyroid tumours and cancer – although a statement from Novo Nordisk said: “The safety data collected from large clinical trial programs and post marketing surveillance have not demonstrated a causal association between semaglutide and thyroid cancer.”

A long-term measure for those in extreme circumstances

And, long term, we just don’t know what semaglutide might do. These are relatively new drugs – Wegovy was only launched in the UK in September 2023 – whose longest trials only lasted a few years.

Previous supposed ‘miracle’ weight-loss drugs have since been pulled from the market for causing harmful side effects, including heart valve damage, strokes, lung conditions, and psychosis.

Yet semaglutide – especially as Ozempic – is often recommended as a long-term treatment.

Van Zyl explains: “The evidence is suggesting that for some people, like with type 2 diabetes or significant comorbidities, longer-term approaches are advised.

“This is all according to NICE guidelines, and I think we need to really respect those NICE guidelines.

“But until we do longer-term studies – of which people taking it now, essentially, will be the guinea pigs – then we’re not going to know definitively whether this is going to be safe long term, or whether it is safer as a short-term intervention.”

But people may not want to only use semaglutide as a short-term measure, because its effects only last as long as people are on it.

Indeed, a 2022 trial showed that people who stopped taking semaglutide regained two-thirds of the weight they had lost within a year of stopping.

So, just going on semaglutide and then coming off it again, without making other changes, will only put the body through the stress and strain of fluctuating weight.

Who is eligible to take semaglutide in the UK?

Also, it should be reiterated that semaglutide is only meant to treat type 2 diabetes and obesity.

The NHS recommends that Ozempic should only be prescribed to people with insufficiently controlled type 2 diabetes, and Wegovy is for people with a BMI of 30 or more, or a very high BMI (at least 27) and significant comorbidities, i.e. problems linked to their weight such as heart disease.

For clients with lower BMIs, Van Zyl says she would recommend that they try the traditional approach: nutrition, counselling, behaviour change and exercise.

“Let’s give that a go first,” she says. “Let’s see what’s going on for you biochemically. Let’s use a constant glucose monitor. Let’s do some urine tests and see what’s going on.

“If it becomes apparent that this is an ongoing, relapsing, recurring problem and people are just going to lose the plot because they aren’t getting the change, then absolutely, let’s have the conversation [about semaglutide].

“But it’s not my starting point, particularly with people that have one, two, or three stone to lose – and I’m saying that loosely.”

There are some individual cases, she says, where semaglutide might benefit those who have lower BMIs, such as somebody with type 2 diabetes and severe comorbidities.

But this drug hasn’t been tested on people without or with slight overweight, so we don’t conclusively know that it’s safe for those people.

How semaglutide can be used in clinic

So, if semaglutide is only effective as long as clients are on it, and it may not be safe long term, is it worth going on at all?

For type 2 diabetes, semaglutide can be an effective medication for regulating blood sugar and eliminate the need for injecting additional insulin.

For those with obesity, Van Zyl says it can be beneficial for those who struggle to lose weight and could do with some help kickstarting that process.

She explains that a lot of people with obesity are obsessed with food and constantly triggered to crave it by their environment.

“For people wanting to lose weight,” she says, “that constant hunger is an incredible barrier for them, and very, very difficult to work with.

“You’re in an environment where you’re triggered all the time… That makes it very difficult if you’re trying to lose weight.

“Having that variable removed [i.e. appetite] means you can actually focus on the task at hand, and that really is [implementing] the lifestyle and behavioural change.”

Semaglutide is not designed to be used on its own

Novo Nordisk states that Ozempic should be used “as an adjunct to diet and exercise” and Wegovy “as an adjunct to a reduced-calorie diet and increased physical activity”.

All their clinical trials measured the effects of combining semaglutide with lifestyle changes, such as a restricted diet, a weekly exercise goal and monthly healthcare check-ins – not just the drug alone.

And Van Zyl explains that this is how they should be used: as one tool in the arsenal of multi-disciplinary teams who guide their patients or clients through long-term treatment plans.

On the NHS, patients on semaglutide address nutrition with a dietician, physical activity with a physiotherapist, basic medicine with a doctor (a surgeon or endocrinologist, depending on their treatment), and psychology too.

And in the private sector, treatment might include a nutritional element, psychotherapy, support from medical doctors, guidance on physical activity, and the option to choose surgery or medication.

Van Zyl describes semaglutide as a scaffolding that can be put in place to allow people to focus on these other changes: “You can take a step back and just look at: ‘What is going on for me? Why am I eating this way?’ What is your ‘why’?

“Semaglutide is one of the ‘how’s. On its own, yes, you can have dramatic weight loss, but… people who are successful are the ones that have the support.

“They do the exercise, follow the healthy diet; there is the change, and it’s sustained. It’s not happening in isolation.”

Is sustainable weight loss achievable without semaglutide?

Yet some practitioners are more reluctant for semaglutide to be used at all. Nutritional therapist and ION alumni Janie Perry says: “As a holistic practitioner, I would be wanting to do things a natural way.

“I think [semaglutide-based drugs have] got massive side effects and … the weight loss is dramatic and actually, I just do not think it’s healthy. I’m all for food first.”

Perry insists that people with obesity can lose their excess weight purely through diet and lifestyle changes, such as reducing sugary foods, eating whole foods, and including carbs, protein and fats in every meal and snack.

For Perry, sustainable weight loss is “all about simple changes, implemented slowly”.

“I look at sustainable weight loss like a marathon, not a sprint,” she says. Diet and exercise are “the crucial components”, and beyond that she works with her clients to improve sleep, stress management, meal timings and blood sugar control.

And, to get past cravings and food obsession, Perry encourages her clients to eat often – three meals and two snacks per day – something she acknowledges many would “shout her down for”.

“It means they don’t obsess,” she explains. “They know they’ve only got two and a half hours to go until the next meal or the next snack, so they’re not constantly feeling deprived and thinking, ‘oh my god, it’s hours till I eat again’.”

Without semaglutide, many people trying to lose weight hit a metabolic barrier; weight loss becomes an uphill battle because the body is trying to maintain what it believes to be its ideal weight, called a weight set point.

Perry says that this is when she would encourage her clients to focus on the “marginal gains”, gradually cutting down on their snacks, extending their overnight fasting period by eating a later breakfast or earlier dinner, and using a continuous glucose monitor to find out which foods work best for them.

But Van Zyl says that practitioners may be able to use semaglutide to bypass this metabolic hurdle (“speaking hypothetically,” she clarifies) by implementing weight loss consistently but gradually and with periods of plateau to “allow the body time to adjust to that new weight”.

Will semaglutide solve the obesity crisis?

Despite all that semaglutide can do, it is unlikely to nip the growing obesity epidemic in the bud.

These drugs help individuals who have already developed obesity to manage and perhaps reverse their condition; they don’t prevent more obesity in the future.

Van Zyl says: “From my perspective, obesity is not an individual-level problem. It’s a societal-level problem. It’s not a case of willpower. We are in what you could classify as an obesogenic environment.

“[We need to] recognise the societal influences, with food production, pollution, community access to green space, exercise, working practices…

“The issue we have extends beyond you eating food. It’s what food are you eating? Can you afford to buy good, healthy, organic, natural food? How much nutrition is in your food?

“What’s driving things like hyper-processed food production, and what are the impacts of that? For a lot of people, the bottom line is, can I afford it?”

Van Zyl hopes that more research will go into functional medicine and natural alternatives to semaglutide that might help people with obesity, but in the meantime, she believes semaglutide can benefit some people.

She says: “Semaglutide – yes, it is exciting. It is revolutionary in terms of what it can do. I’m glad to see that it’s addressing the hormonal basis [of obesity].

“But it’s one aspect of the treatment… It’s a tool, and we need support around that, otherwise people are going to be set up to fail, and that sucks.”

Enjoyed this article?

Learn about 'Fat Bear' winter: backlash against the wellness industry

For articles and recipes subscribe to the Optimum Nutrition newsletter

Discover our courses in nutrition