Why the Mediterranean diet is the only low-carb diet that works
Cutting down on carbs sounds like a straight forward route to weight loss. Ditch the roast potatoes, risotto and pasta and watch the pounds drop? Simple.
Indeed, a randomised trial published in 2023 in The Annals of Family Medicine took 94 overweight or obese adults with high blood pressure and diabetes or pre-diabetes, and put them either on a very low-carb (VLC) diet or a DASH diet, which restricts saturated fat and total fat, favouring fruit, vegetables, whole grains and low-fat dairy. The VLC diet saw greater improvements in blood pressure, blood sugar and weight loss than the low-fat DASH diet (nearly 20lbs, versus just over 10lbs.)
Low-carb diets work brilliantly for a short time. However, if you skimp on vegetables – prioritising protein and fat -and get too little fibre (only found in carbohydrates) – you raise your risk of bowel cancer, heart disease and stroke.
A healthy low-carb diet means being rigorous about getting enough fruit, vegetables, pulses, and fibre, all of which are healthy carbs. So you’d need to add spinach, mushrooms, kidney beans and onions to your omelette, or eat braised lentils and asparagus with your fish. But most low-carb devotees aren’t doing that.
What is a low-carb diet?
The majority of people eat a diet that’s 50 per cent carbs. Think porridge or toast for breakfast, a sandwich for lunch, oatcakes and fruit as snacks, then tuna pasta followed by apple crumble for dinner. Following a low-carb diet by removing all sugary and most starchy carbs, cuts that to between 10 per cent (20-50g daily, very low) and 26 per cent (less than 130g daily, low).
Peter, 51, a consultant from Brighton, is a veteran of low-carb diets. “I’ve done all the low-carb diets there are, from Montignac to Atkins.” He’s a fan simply because he eats less on these diets. “That’s why they work for me – it’s the carbohydrate where I find it easy to eat the most calories.” So if he’s not eating carbs, his calorie intake decreases.
Science tells us that by reducing sugar intake and therefore insulin production, eating a low-carb diet improves metabolic function and leads to weight loss. It may also improve other health markers, such as blood pressure.
Why are low-carb diets so effective?
All carbohydrates break down into sugar. Starchy carbs like rice and pasta are notable offenders as they flood our blood with glucose. This causes a sharp insulin spike to escort the glut of sugar out of the blood and into our cells. Eating mainly these foods can overload our system and stress the body. Long-term, repeated excess insulin leads to insulin resistance and causes chronic inflammation, while excess sugar is readily stored as fat, including visceral fat, which is stored more deeply in the body.
So by lowering our carb intake, we reduce insulin spikes. Insulin is known as the “energy storage” hormone, as when it’s circulating, we burn less fat. Conversely, as low-carb diets necessitate eating more protein and fats, our body is more often kicked into fat burning. These foods also make us less hungry, while following a low-carb diet also means eliminating calorie-dense junk food, which results in weight loss.
Peter lost two stone in four months and reckons the mere fact he eats fewer calories on low-carb regimes is why they work. “I believe that all the blood and insulin stuff is not as important to people for weight loss as not eating bread and rice and sugar.”
Different types of low-carb diets
Atkins
The Atkins Diet starts off with 20g carbs daily. It’s high in fat and protein, with low-carb veg. Atkins says yes to meat, fatty fish, seafood, eggs, spinach, broccoli, asparagus, butter, cream, yogurt, cheese, nuts, seeds, extra-virgin olive oil and avocados. But it’s a no to lentils, beans, chickpeas, bananas, apples, “low-fat” foods, potatoes, sweet potatoes, wheat, spelt, rice, barley, rye and sugary foods. After two weeks, you add in more greens, nuts and a little fruit. When you’re close to your target weight, you add in more healthy carbs (such as lentils and chickpeas) then maintain this.
Clinical nutritionist and research scientist Dr Federica Amati, author of Recipes for a Better Menopause notes, “Atkins recommends this slow reintroduction of healthy carbs”, but in reality you eat loads of unhealthy bacon and cream.
Keto
The keto diet restricts carbs to under 50g daily, with moderate protein restriction to induce ketosis (when the body burns fat, not glucose) and a high fat intake. You eat meat, fats and non-starchy vegetables like spinach, cabbage, and kale. Other veg, fruit, legumes, grains and sugary foods are forbidden. “Keto has benefits for children who have drug-resistant epilepsy,” notes Amati. Otherwise, “I’d never recommend keto, Atkins or Dukan for anybody.”
A review published in 2020 in a respected medical journal notes that common initial side effects of the keto diet include fatigue, headache, dizziness, nausea, vomiting and constipation (“keto flu”). Researchers cited long-term risks as “hepatic steatosis [fatty liver disease], kidney stones, hypoproteinemia and vitamin deficiency”. Dr Amati says: “It used to be quite effective because it made people remove all processed, packaged and UPFs.” Now they fill up on “keto-friendly” bars, cereals and bread.
Dukan
The Dukan diet begins with a week of unlimited lean protein plus oat bran; then one to 12 months of adding in non-starchy veg on alternate days; then unlimited lean protein and vegetables, some carbs and fats, and a day of lean protein weekly, with, 2.5 tablespoons of oat bran daily. It’s horribly restrictive and “recommends processed meat”, according to Amati.
Peter certainly found this to be the case. “On a low-carb diet, I end up eating food with tons of salt and sulphites in it. Bacon, sausages, fried eggs, not much fibre, and a lot of salt and fat. It’s very easy to do it lazily. I was living on cheese, peanuts and salami. You see people eating ‘low carb’ at the office – wrapping cheese up in ham slices for lunch – and it’s ridiculous. It’s also bad for your gut.
“After a month, you’re craving vegetables, but that’s a faff – it takes a lot of effort and thought to do [a low-carb diet] properly.”
Is a low-carb diet healthy?
It’s true that a refined carbohydrate like white rice is of low nutritional value and quickly breaks down into sugars, causing a sharp blood glucose spike and insulin response. And if our blood sugar is dramatically zigzagging every day because the bulk of our diet is ultra-fast-digested carbs, our risk of weight gain and chronic disease rises.
However, Dr Amati stresses that it’s not the white pasta or rice in itself that’s the issue. “It’s when white pasta or white rice is the majority of your plate. These white starchy foods are okay if they are part of a dish.” She also notes, “If we are healthy and eat well, our body does a very good job of maintaining healthy sugar levels for us.”
But as we age, metabolism slows and glucose tolerance declines. According to Dr David Unwin, known to his 99,000 social media followers as @lowcarbGP, we should all aim to improve “the average sugariness of the blood” and our glucose spikes. While a small glucose spike is “completely normal” after food, regular large blood sugar spikes in the long term increase the risk of disease, including heart disease.
How else can cutting our carbs benefit us? Unwin notes that 38 per cent of the world’s population are estimated to have NAFLD – non-alcoholic fatty liver disease (described in a Washington Post article as “the worst disease you’ve never heard of”). Fat accumulation in the liver contributes to the development of Type 2 diabetes and all metabolic disease. “This fat comes from excess consumption of refined and free sugars, as well as added fats in UPFs (ultra-processed foods), like esterified palm oil in a ready-made pizza or lasagne,” says Amati.
Meanwhile, a low-carb diet has been transformative for 133 Type 2 diabetic patients of Unwin’s at the NHS Norwood Avenue surgery in Southport, who prioritised “nutrient-dense healthy food that doesn’t put your blood sugar up”, including green vegetables, eggs, oily fish, chicken or red meat, nuts and full-fat dairy. The patients lost an average of 12 per cent of their weight and reversed their diabetes.
Unwin, a RCGP clinical expert in diabetes, says: “Of my patients who go low carb, 50 per cent achieve drug-free remission after 33 months, and 97 per cent have seen an improvement in diabetic control.”
Fellow medics warned that increasing the patients’ protein and fat would increase cardiovascular risk. But Unwin’s data – published this year in the journal BMJ Nutrition, Prevention & Health – shows it’s been significantly reduced, with patients lowering their blood sugar, blood fats and blood pressure.
He says: “Haemoglobin A1C, the sugariness – probably the most important cause of cardiovascular disease – improves by nearly a third. And triglycerides – a really important factor for cardiovascular risk – improve by 35 per cent.”
The downsides of a low-carb diet
The results can be life-changing, as Unwin’s patients would attest. Amati says: “For people with severe obesity, the benefits of losing weight rapidly outweigh the risks. Anyone else wanting to lose a bit of weight, you’re better off doing it more slowly.”
She adds: “One reason is that restrictive diets are problematic and normally not sustainable. Atkins, like the Dukan diet, increases the risk of cardiovascular disease and can increase incidence of colon cancer for those predisposed. We don’t have that data for the keto diet – probably because it’s even less sustainable.”
With Atkins and keto, “most people go the full hog, stripping everything out. It feeds into yo-yo dieting and people thinking, ‘I’ve got a bit heavy, I’ll just eat meat and high protein until I get back to my target weight, then go back to normal’.” But this isn’t healthy, as cutting out whole food groups removes lots of nutrients and, crucially, the fibre we need for a healthy gut.
Rapid weight loss on an unsustainable diet is also a recipe for yo-yo dieting, which doesn’t work “because the physiology of weight loss is different to the physiology of weight-loss maintenance”, according to Amati. “Once you’ve lost the weight, maintaining that lower weight is harder.” Fast weight loss is a red flag, “a signal to our body to store more fat again because it thinks we’ve gone through a period of famine”. Revert to your normal diet and you gain weight - as Peter discovered himself. “It’s not sustainable in the long-term. You revert to the diet that made you fat in the first place and always put weight back on.”
What are the health risks of a low-carb diet?
Low-carb diets such as like Atkins, keto or Dukan favour high amounts of saturated fat, which some studies show can raise LDL (low-density lipoprotein) levels, sometimes called “bad” cholesterol.
What’s more, by banning lentils, beans, pulses and most fruit, as some of these low-carb diets tend to, you lose vital micronutrients, says Amati. And she doesn’t recommend eating loads of cream and butter, as included in the Atkins diet, for example: “You will see an increase in LDL at some point. There’ll be a lot more triglycerides floating around.”
And what protein we eat matters. As Unwin notes, “pepperoni and a Diet Coke is low carb, but clearly not healthy.” Amati cites a study of more than 200,000 people, published in The American Journal of Clinical Nutrition in 2023, which found that total processed and unprocessed red meat consumption was linked with a higher risk of Type 2 diabetes. Researchers found that limiting red meat to once a week would be sensible for people wanting to optimise their health. And if you swap red meat for another protein source, such as making a chilli with beans instead of beef, you lower your diabetes risk considerably. Amati says: “Substituting one portion of red meat daily for nuts and legumes was linked with a 30 per cent reduction in risk.”
Why the Mediterranean diet is the only sustainable low-carb diet that really works
“There’s no need to reinvent the wheel,” says Amati. “We have plenty of evidence that an abundant Mediterranean diet can prevent and even reverse non-alcoholic fatty liver disease and Type 2 diabetes, can lower cancer and heart disease risk, and it’s a way of healthy eating that most people can maintain for life.”
In the Med diet, you eat oily fish like salmon, other fish and seafood, vegetables, fruit, wholegrains like brown rice, nuts, seeds, legumes such as lentils and heart-healthy extra-virgin olive oil. You eat moderate to low amounts of poultry, eggs, yogurt and cheese, and limited red meat and red wine. Processed meat, added sugars and UPFs are occasional.
How a typical Mediterranean day looks
Breakfast: Shakshuka (eggs poached in tomato and red pepper sauce)
Lunch: Tuscan ribollita with barley (a vegetable and bean soup with Parmesan)
Dinner: Pesce all’acqua pazza (white fish in tomato sauce with basil and extra-virgin olive oil) and sourdough bread
Snack: Full-fat Greek yogurt with kefir, berries and nuts
Consequently, Amati recommends the Mediterranean diet, “prioritising unrefined wholegrains with a low glycaemic index [a lower glucose load] and probiotic fermented foods [like yogurt] to support our gut microbiome”. Buckwheat, barley and spelt are low-GI wholegrains, for example. She adds: “Over 90 per cent of us would benefit from eating more fibre-rich foods” – the ideal is 30g daily – “so I’d focus on adding vegetables, pulses, legumes, wholegrains like barley, nuts, seeds, berries, whole fruits, mushrooms and other plants to our plates.”
The Mediterranean diet has very little refined carbs (such as white rice). “It has wholegrain pasta, and traditionally made sourdough wholegrain bread.” To lower carbs, if you’re attempting to reverse Type 2 diabetes, limit these to, say, one slice of bread a day and/or a handful of pasta.
Other Mediterranean Diet ingredients include kefir and sauerkraut. Amati says: “If you eat a variety of high-fibre and fermented foods, you feel satiated and get all the nutrients you need. It might take longer to lose weight, but it improves all health outcomes and is sustainable.”
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