The 4:3 weight loss plan that stops diabetes in its tracks

Telegraph

12 hours ago

The idea is simple: eat whatever you like for four days and cut back for three. In theory, the 4:3 diet means you can forget about what you're eating for most of the week and still lose weight.
And it works. In a recent study, it has been shown to be more successful than other calorie-controlled plans. Researchers at the University of Colorado Anschutz Medical Campus found those on the 4:3 diet lost an average of 7.6 per cent of their body weight, compared with 5 per cent for those who simply cut calories. The 4:3 group also demonstrated healthier blood pressure, cholesterol and glucose levels.
'The beauty of a regime like this is that it's user-friendly. You can fit it into your lifestyle, over a period of days,' explains Dr Adam Collins, an associate professor of nutrition at the University of Surrey. 'Meanwhile, you're forcing your body to shift from storing carbohydrate to burning fat.'
But, before you jump in, a word to the wise: 'It's pretty miserable on fasting days,' says Jo Travers, a dietitian and founder of the London Nutritionist, who has tried it herself and says it's not for the faint-hearted. So, is it worth it? Do the health benefits outweigh the drawbacks?
How the 4:3 diet works for weight loss
The diet's effectiveness is due to the fact that participants don't have to count calories or restrict food every day, according to the Annals of Internal Medicine, which published the results of the 12-month study.
It's a step up from 5:2 diet, made famous by the late Dr Michael Mosley, which involved fasting for two days. On the 4:3, you have three non-consecutive days of fasting each week. Only 500 calories are permitted on these fasting days, though you can drink water, black tea and coffee.
On the four 'free eating' days, participants are still encouraged to eat healthy, nutritionally balanced meals. Travers ate her normal, healthy diet with plenty of vegetables, wholegrain carbs, beans and white fish.
Participants in the study often ended up eating fewer calories than they usually would on 'free-eating' days. 'The results show that those following the diet don't tend to overcompensate on non-fasting days,' Dr Collins says.
This might be because the diet is so hard – people want to make the most of the effort they've put in, so they start eating more mindfully, he says. Or it could be that fasting helps improve satiety control, and they feel less hungry. 'Fasting is tough, but when you start to see results, you're more motivated to keep going,' he adds.
There's nothing miraculous about the 4:3 diet, Dr Collins says; you're simply creating a calorie deficit throughout the week, which leads to weight loss. 'The more days you fast, the more weight you lose,' he explains. However, beyond calorie restriction, fasting triggers several metabolic changes that can make weight loss more efficient.
When you fast, insulin levels drop significantly – and low insulin levels facilitate fat burning. Additionally, when your digestive system isn't constantly processing food, the body initiates a process called autophagy – a cellular 'clean-up' operation which may reduce inflammation over time. 'This self-repair mechanism is one of the proposed benefits of intermittent fasting beyond just weight loss,' says Dr Collins.
Even the gut microbiome may benefit from fasting. Some studies suggest that periods without food allow beneficial bacteria to thrive, while helping to regulate appetite hormones (such as ghrelin and leptin), which play a key role in hunger and satiety.
Scientists also credit fasting with helping to lower blood pressure and inflammation, both of which are risk factors for diseases such as type 2 diabetes and cardiovascular disease.
The health benefits of fasting
Research shows that adhering to a time-restricted intermittent fasting diet could help lower your risk of type 2 diabetes.
Some studies show that fasting reduces inflammation, which is the cause of many chronic diseases.
It has also been shown that intermittent fasting can lower 'bad' LDL cholesterol, blood triglycerides, inflammatory markers, blood sugar and insulin resistance – all of which are risk factors for heart disease.
Animal studies suggest that intermittent fasting may be beneficial in protecting against cancer.
How does it make you feel?
Fasting, particularly in the early stages, can cause irritability, light-headedness and anxiety, although some people find that it improves mood and energy levels. It doesn't suit Travers: 'I get really hungry and grumpy and can't concentrate,' she says. She recommends seeking professional support from a dietitian before embarking on any intermittent fasting diet. 'They'll help you decide if it's right for you, and structure a meal plan,' she says. 'It's easy to feel like a failure with a regime like this – it's much easier if you have a manageable plan.'
Travers also advises that you're especially mindful of your nutrient intake, making every meal count. 'When you're fasting, you're missing out on nutrients your body needs,' she warns. 'You need to eat plenty of vegetables and fruit, and make sure you include sufficient protein on non-fasting days.'
What exactly should you eat on fasting days?
You can choose between one 400kcal meal and a snack, or two or three lighter meals, plus plenty of water and herbal teas to stay hydrated. You can even have a coffee for an energy boost. Even though you're fasting, Travers still suggests eating three meals, focusing mainly on vegetables and fruit – you will need the vitamins, minerals and polyphenols they contain, as well as fibre. 'There's a risk that if you don't eat enough fibre to feed the bacteria living in the gut, you'll actually impair your gut health,' she says.
For the nutritional therapist Gabriela Peacock, a 4:3 advocate whose clients include Donna Air and Jodie Kidd, a fasting day would comprise of yogurt or a boiled egg for breakfast, spicy soup for lunch and a stir-fry with a small amount of chicken for dinner. She has a selection of 4:3-friendly recipes on her website, including boiled eggs and asparagus (124 calories), tuna salad (99 calories) and courgetti with mushroom ragu (109 calories).
What about the non-fasting days?
Part of the 4:3 diet's appeal is that you can enjoy your favourite meals on non-fasting days – even a glass of wine if you feel like it. Travers doesn't like to hand out specific recipes to her clients; instead, she helps them tailor their favourite dishes to suit their eating plan. If they're stuck for ideas, she always recommends something Mediterranean.
If you're trying to lose weight, she suggests a fist-sized portion of carbohydrate, two handfuls of veg, and a palm-sized serving of protein. Then, balance the recipe by making sure there are enough vegetables, wholegrains, spices, nuts and seeds.
'Try to focus on what you're adding, rather than what you're taking away,' she says. As for pudding, if weight loss is your goal, try to give it a miss even on non-fasting days. 'I generally recommend olive oil as a source of energy rather than sugar,' Travers continues.
Who suits the 4:3 diet?
It works well for people with time, head space and determination, Travers says – as well as for people who aren't particularly focused on food or don't get hungry. 'In my experience, the people who are best at fasting are those who don't need to lose a lot of weight,' she says. 'I don't recommend that people do this diet. But if they really feel they must do it, they should eat a lot of vegetables, do it for short period of time and make sure they eat a balanced diet on their non-fasting days.'
Who should avoid it?
The 4:3 diet isn't usually suitable for pregnant or breastfeeding women or children, Travers warns, as well as those with health conditions. You might find it tricky if you're on your period or going through the menopause, she adds, as fluctuating hormones can deplete your energy levels and mood even further. It's also not the right diet for those with a history of disordered eating or eating disorders. 'If you have a tough relationship with food, diets like this can actually create more stress in the mind,' says Beanie Robinson, a nutritionist and founder of The Health Space. 'Even the language of the 4:3 diet – 'free eating' and 'fasting' – encourages bingeing one day and a sad, restrictive approach the next, which can play havoc with female mental health and hormones. People begin to forget what 'normal' eating looks like.'
Is intermittent fasting more successful for weight loss than time-restricted eating?
The jury is still out on this. Time-restricted eating – where you fast for 12 to 14 hours each day – is also showing positive results in weight-loss studies. 'Fasting overnight is definitely easier – you can simply push breakfast later or eat earlier in the evening to get the full 12 hours,' Dr Collins says. 'Yet with 4:3, you'll probably create more of a calorie deficit over the course of seven days.' Travers, who has also tried time-restricted eating for research purposes, says the hardest part was missing her milky morning coffee. 'I had to have black coffee, and this put me in a bad mood all morning.'
What happens afterwards? Will I put the weight back on again?
If you go back to your old habits, you will gain weight again, Travers says. 'People tend to think 'thank goodness that's over' and start eating like before.' Eating healthily and in moderation on the non-fasting days will help instil positive habits once the diet is over, she continues.
While the 4:3 diet isn't something you would want to continue permanently, Dr Collins can see the benefits of continuing with regular fasting – just in a less extreme way. 'The metabolic effects are the interesting part,' he says. 'Even in a few hours, your body has transitioned to fat burning. Dramatic results are great, but it's also important to think of health as something you're managing for the rest of your life.'
Both Travers and Dr Collins believe there are other ways to bring fasting into your diet. 'In my experience, you can get just as good results from eating well with an overnight fast,' Travers says. The Granny Diet is Beanie Robinson's go-to: simple, homemade breakfast, lunch and dinner with no snacks in between. 'No one knows what they're meant to be eating anymore – they're so confused by what they've seen on Instagram and TikTok,' she says. 'Diets like the 4:3 can be difficult for women with fluctuating hormones – our bodies love regularity. Eating three healthy meals a day with a 12-hour fast overnight is brilliantly basic, and many of my clients find themselves losing weight.'