While he acknowledges GLP-1s have a role to play, he and other doctors are concerned the drugs are being promoted as a fix-all, and are quietly proving that targeted diet and lifestyle programmes can achieve similar results – without side effects.
“You can stimulate your own GLP-1, naturally, through food and exercise,” says Unwin, who is known for pioneering the low-carb diet for obesity and diabetes in the UK. “A low-carb, high-protein diet is shown to boost GLP-1 levels. And it doesn’t come with nausea or cost a fortune.”
Campbell Murdoch is a UK GP with a special interest in metabolic health who launched a Metabolic Health 28-Day Plan combining a high-protein, low-carb diet with time-restricted eating, movement, easy lifestyle changes and mindset support. Originally created for NHS patients at his practice in Somerset, the results were so positive, the programme has been made freely available online.
“The GLP-1 boom has at least put metabolic health on the radar,” says Dr Murdoch. “Now we need to give people complete solutions, including lifestyle, not just the drugs.”
Here are the three diets doctors recommend.
Low-carb diet
Key benefits: simple and sustainable
The low-carb diet is proven to get results and can curb food cravings, reverse type 2 diabetes and deliver comparable weight loss to GLP-1s, suggests latest research.
Cutting down on sugar and starchy carbs deprives the body of its primary fuel, glucose. It starts burning body fat instead, leading to weight loss. Blood-sugar levels stabilise, appetite regulates, and insulin levels fall, leading to better metabolic health and lower risk of type 2 diabetes and cardiovascular disease.
Unwin has been spearheading the low-carb approach at his NHS clinic in Southport for the past 13 years, with striking results. “On average, patients lose 10kg (22lbs) in the first year,” he says. “We’ve helped 151 people achieve drug-free diabetes remission. That’s 27% of our diabetic population. We’ve saved £370,000 on diabetes medication.”
In total, 51% of Unwin’s patients with type 2 diabetes achieve remission, another 47% get better control over their condition. And over 90% of patients with pre-diabetes return to normal blood-sugar levels.
Unwin’s approach has been adopted all over the world, through The Low-Carb Program and a free NHS-approved app.
The method is simple, says Unwin. “Eat a nutritionally dense diet that doesn’t raise your blood sugar.” Officially, low carb means eating less than 130g of carbs a day (for context, one apple is 25g, a bowl of pasta 40g). However, Unwin recommends focusing less on numbers and more on cutting out sugar and starchy carbs, like bread, cereals and potatoes, while increasing protein and green veg. A typical low-carb meal might be baked salmon with asparagus and cauliflower rice.
“When you eat in a way that doesn’t spike blood sugar, and includes enough protein, you stay feeling full, partly through natural, GLP-1 production,” explains Dr Unwin.
Kirsten Linaker, 48, turned to the low-carb diet after weight-loss injections failed to help her. “Dr Unwin gave me simple diet advice and a blood-glucose monitor, so I could see how foods like chocolate spiked my blood sugar,” she says. “Now, I’ve lost almost 6st (38kg) and have gone from size 26 to 14. I’m off my diabetic medication, and my food cravings have gone. I used to sit in bed at night, eating biscuits, now I’m just not hungry anymore. I don’t even miss sweet stuff.”
If you’re following a low-carb diet, be sure to include nutritious foods, rich in fibre. If you have an existing medical problem, see your GP first.
Keto diet
Key benefit: rapid results
The ketogenic, or “keto” diet, is a more restrictive, high-fat, even lower carbohydrate approach designed to induce a fat-burning state in the body called ketosis. Followers of the diet aim for 20-50g carbs per day (drastically less than the 130g as on the low carb diet). It’s proven to offer immediate weight loss and appetite suppression, with metabolic-health benefits.
“In my experience, the keto diet gives the same benefits as GLP-1s, such as reduced appetite and elimination of food noise, without the side effects,” says Dr Eric Westman, associate professor of medicine at Duke University and director of the Duke Keto Medicine Clinic.
When carb intake is drastically restricted, the body switches into ketosis, a metabolic state in which it burns fat for fuel, by converting it to ketones. This reduces blood glucose and insulin, and lowers levels of the hunger hormone, ghrelin. People can lose several pounds in the first week, gradually slowing to a more sustainable rate.
Westman’s clinical research has shown that a keto diet can put type 2 diabetes into remission. Around 98% of his patients with type 2 diabetes come off insulin. “Patients typically lose one to two pounds a week,” he says. “I can safely de-prescribe medications for diabetes, hypertension, heartburn and arthritis.”
A meta-analysis of trials, in Nutrients, found that ketogenic diets gave better weight loss and blood-sugar control than a low-carb diet.
Sharon Grey, 56, was almost 18st (114kg) and living with type 2 diabetes, Nash (non-alcoholic fatty liver disease), high blood pressure and depression before she began Westman’s keto programme (adaptyourlifeacademy.com). After 13 months, her weight had dropped to 12st 8lb (81kg). “I reversed my type 2 diabetes and Nash, and my blood pressure is normal again,” she says. “My headaches, backache and knee pain improved, my mood is better and I’m taking fewer medications.”
The key to keto success is to keep carbs under 50g a day. Include plenty of protein, says Westman. “Protein is critical as it helps you feel full, and ensures you lose fat, not muscle,” he says. “Don’t overdo the dietary fat – if you eat too much of it, your body will burn that, rather than body fat.” His top five keto foods are eggs, meat or poultry, seafood, non-starchy veg (like cauliflower or broccoli) and leafy greens.
So when should you choose keto, rather than a low-carb diet? “Keto isn’t always necessary, but in severe cases, it can be beneficial,” says Murdoch. “The keto diet offers rapid results and some patients feel better on it,” adds Unwin. “However, it’s more complicated than a standard, low-carb diet, and not essential for reversing type 2 diabetes.”
Transitioning to ketosis can trigger temporary fatigue and nausea, called “keto flu”. If you’re on medication, or have a medical condition, only try keto under medical supervision, advises Dr Westman.
Intermittent fasting
Key benefits: cheap and effective
If you don’t like calorie counting, focusing on when you eat, rather than what you eat, could be the solution. Intermittent fasting – alternating periods of eating and fasting, such as the popular 5:2 diet – can lead to an average weight loss of 5% to 9% of body weight over three to 12 months, according to research.
“When we don’t eat, the body moves into fat-release mode,” explains Dr Murdoch. “Fasting gives the body longer to use up stored sugar and burn body fat. That’s why it improves blood-sugar control, too.”
Among the most effective fasting methods is time-restricted eating (TRE), where you consume your food within a defined window each day, followed by an overnight fast. A study at Manchester Metropolitan University found that just three days on the 16:8 method (eating within an eight-hour window and fasting for 16 hours) significantly improved blood-sugar control in people with type 2 diabetes.
“TRE offers promising benefits for weight loss, glucose regulation and metabolic health – without calorie counting,” says study lead Dr Kelly Bowden Davies. “While average weight loss is typically less than with GLP-1 drugs, prolonged use of TRE is a cheaper, safer and more accessible alternative – especially when combined with lifestyle changes.”
That’s the approach taken by Murdoch with his Metabolic Health 28-Day Plan. It combines time-restricted eating (11am-7pm), focusing on lower-carb (often under 70g a day), high-protein (1-2g per kilo of body weight a day) foods, daily movement (for example, squats while the kettle boils) and seven hours’ sleep, presented as a tick list of 10 daily habits.
“People often lose half a stone to a stone in the first month,” says Dr Murdoch. “Blood pressure, blood sugar, mood and energy all improve. It’s as effective as GLP-1s, for a fraction of the cost, and with far better sustainability.”
Donna Brewer, 48, weighed nearly 22st (140kg) when she started the plan in April. “I’d gradually gone from a size 14 to a 24. I felt sluggish, tired, anxious, and my blood pressure was dangerously high,” she says. “After 28 days, I’d lost almost one-and-a-half stone (9.5kg). Now I’m down more than 2st (12.7kg), my waist’s shrunk from 130cm to 118cm, and I’m off medication. I feel so much happier and more energetic. It’s not like a diet – more a shift in mindset.”
The health risks of GLP-1s
Using GLP-1 drugs without nutrition advice or lifestyle support can lead to malnutrition and even accelerated ageing, caution experts. “GLP-1s reduce appetite but if you simply eat less of a regular, poor diet, you risk becoming deficient in protein and nutrients – and this drives muscle loss,” says Murdoch. “We’re already seeing muscle loss and then weight regain when people stop taking the drugs.”
An Oxford University review found that most people regain the weight within 10 months of stopping GPL-1s. “The drugs are only licensed for two years [and many patients give up earlier],” says Murdoch. “After that, if you haven’t changed your habits, the weight comes back – and you’ve lost muscle along the way, which is hard to get back.”
In a recent clinical trial, 42% of over-60s lost at least 10% of their muscle power – the equivalent of ageing 7.5 years – within six months of taking the GLP-1 drug semaglutide. “You need to pair these drugs with resistance training and proper nutrition, particularly protein,” says Murdoch.
GLP-1s do have a role to play, say the doctors. “For people addicted to ultra-processed food or who struggle to give up starchy carbs, GLP-1s can be a temporary tool, if combined with nutritional support,” says Dr Unwin. “I recently had a 75-year-old patient who lost a stone and a half and came off insulin by combining a GLP-1 with a low-carb diet.”
However, he and other doctors are concerned the drugs are being promoted as a fix-all. “The way weight-loss drugs are being pushed as a default solution is worrying,” says Dr David Jehring, chairman of the PHC, chief executive of Black Pear Software and creator of Elevate, a new AI personal health coach, soon to be trialled in the NHS. “GLP-1s are now so widely available, primary care services are being told they don’t need to offer dietary interventions.”