‘Diet’ is arguably a misleading appendage attached to ketogenic, advocated as a weight-loss regime in a similar vein to Atkins and paleo.

First developed in the 1920s by Dr Russell Wilder at the Mayo Clinic in the US as a treatment for epilepsy in children, keto has since been adopted as a low-carbohydrate, high-fat, and animal-protein-slanted diet. And for some consumers and observers outside the keto community, it remains just that.

However, a keto diet is increasingly being taken up as a complementary therapy for a host of health afflictions, primarily high-blood pressure and heart disease, and diabetes or prediabetes because of its low-sugar element from reducing the consumption of carbs.

But keto has attracted a fair amount of criticism from some experts within academia and some nutritionists due to a general lack of medical or scientific evidence to back up the perceived benefits for health conditions, which also include Alzheimer’s and Parkinson’s diseases.

The jury is also still out on its effectiveness and safety as a weight-loss programme. Again, with scant supportive evidence and insufficient research, the diet has been called out for contributing to high cholesterol levels, kidney stones and gout, and intestinal problems, leaving keto wide open to debate.

Key to that debate is the assumption that more people are turning to keto as a health-combatting mechanism, particularly low sugar, rather than for weight loss, making the word diet arguably redundant in the sense of things.

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Nonetheless, there are backers and discounters. Adherents at UK-based suppliers The Keto Collective and Hunter and Gather say the ketogenic diet remains in growth. Catalina Crunch agrees, although the US better-for-you breakfast cereal maker is shifting its model away from keto-centric to intensify its focus on low-carb and low-sugar.

A recent survey by Catalina Crunch, set up in 2017 by diabetic Krishna Kaliannan, found 6% of US households were keto followers, quite significant in a country with a population of more than 331 million, bearing in mind the World Bank figures include children and adults.

We still think there’s a lot of runway for keto, there’s still a lot opportunity

Andy van Ark

“Keto is a trend and we do see ups and downs of trends, but we still think there’s a lot of runway for keto, there’s still a lot opportunity,” chief marketing officer Andy van Ark says.

“Not too long ago, the whole world was on about Atkins but that diet trend really started to taper off. I think there’s a lot of great benefits of keto diets, especially for people like Krishna who are diabetics.

“It’s not just a diet, it’s more of a lifestyle that a lot of people have adopted. That’s really what’s continuing to drive a lot of the growth and the category’s broad appeal. What we’re advocating for is a low-carb, not a no-carb diet.”

Nutritionists tend to disagree

Binay Curtis, a nutritional therapist and fitness expert in the US, resides in the negative camp, although the founder of BodyByBody Fitness and Nutrition dips a toe in the more positive low-sugar pool.

Curtis argues the “body needs proteins, fats and carbohydrates to function properly and form the proper nutrients for your body – if one of those categories is missing, it throws the body off balance”.

She suggests “keto crazy is finally on its way out”. Catering to women in the 40-60 age group, Curtis says she’s always been highly “sceptical” of keto.

“From eating high-fat foods (all the time) to being super restrictive, it is just not the recommended approach I would offer my clients. Most people would come to me and say, ‘keto worked for a while, but now it doesn’t’. Sure, it may work for a while, but, eventually, the body fights back,” Curtis explains.

More sanguinely, she adds: “I’m a true believer in eliminating sugar and processed foods, so if there’s one positive thing I can say about keto, is it taught many people to eliminate processed foods and sugar from their diets.”

How does the ketogenic diet work?

Carbs increase the intake of sugar, which is naturally converted to glucose, the body’s natural source of energy. When carbs are reduced and glycogen levels in the liver are depleted, insulin levels in the blood decrease and the body burns fat from its own stores.

The liver then produces what are called ketones – a type of chemical – which the body uses in the absence of glucose, in much the same way as fasting. When ketones accumulate in the blood by burning fats for energy instead of glucose, the individual is said to enter a state of ketosis.

Although there is no hard rule, to remain in a state of ketosis generally means consuming 20-50 grams of carbs a day, depending on the strictness of the individual’s regime.

Reducing the daily carb intake requires cutting down on common starchy foodstuffs such as bread, grains and pasta, and starchy vegetables like potatoes and parsnips. And some fruits and soft drinks because of naturally occurring or added sugars, processed foods and some condiments and sauces.

Even legumes are omitted, which are touted for their health benefits for increasing dietary fibre beneficial to gut health and bowel function.

Conversely, keto encourages the consumption of animal fats – butter, ghee and lard – and also high-fat dairy products – full-fat yogurt, cottage cheese and other cheeses. That’s where the diet grabs the most negative attention.

Controversially, perhaps, from an environmental perspective, animal proteins like eggs, beef, chicken and pork, with an emphasis on animal organs for a balanced nutrient profile, are also encouraged. Fish and shellfish, along with some berry fruits, too.

Detrimental to health?

Sophie Medlin, a consultant dietitian and founder of CityDietitians, suggests keto has had a negative impact on some of her clients’ health and is ultimately an “unsustainable” diet regime to follow.

“The scientific nutrition community, dietitians in particular, have never been pro-keto diet as an evidence-based intervention. I really hope that the fad for keto goes completely because it’s unhelpful and has caused significant harm to people,” Medlin says.

“We have certain strains of gut bacteria that rely on carbohydrates from whole grains and things like that. If you cut out all starchy fruits and vegetables, your diet suddenly becomes very limited in terms of plants. I see lots of patients with irritable bowel syndrome and other gut symptoms as a result of having undergone a keto diet, even for a relatively short period.

“When we try to eliminate carbohydrates, for the vast majority of people it’s completely unsustainable and ends up being just another failed diet that they feel terrible on.”

Saturated fat, cholesterol argument

The standout criticism levelled at the keto diet is the increase in fat consumption can push up bad cholesterol levels, or low-density lipoprotein (LDL), perceived as the naughty cousin to HDL.

“Keto can potentially increase your bad cholesterol, depending on how you’re doing it,” Medlin argues. “Most people will end up eating more saturated fat and therefore that can have an impact on cholesterol levels.”

Amy Moring, however, the co-founder and CEO of London-based Hunter and Gather and a keto follower herself, says that’s not necessarily the case as long as “healthy” saturated fats are consumed – ancestral animal-based fats such as ghee, tallow and butter, or even “steak with fat on it”.

“Your body knows what to do with that type of fat. Although you will get an increase in cholesterol initially, it’s more about the ratio of HDL to LDL that’s important,” she argues, perhaps controversially given the health principles emphasised today.

Tallow is the rendered fat from beef or sheep, as opposed to lard, a popular pork fat and cooking oil in years gone by and another preference in the keto diet.

Moring lodges criticism at seed-based oils, suggesting they have a detrimental effect on health, particularly obesity, because of the presence of Omega-6 fats in cooking oils such as rapeseed and sunflower oil.

Omega-6 fats are “highly inflammatory”, she says, noting the widespread presence of rapeseed oil in crisps, pesto sauces and even salad dressings.

“One of the main changes that occurred with obesity was the demonisation of the saturated fats in replacement of these seed oils,” Moring adds. “A lot of people that are true to the keto diet for health would not touch any product with seed oils in.”

Suzie Walker, the co-founder of The Keto Collective, who also got the paleo-centric The Primal Pantry off the ground before it was sold to Nurture Brands in 2020, says there’s a big debate around cholesterol. Interestingly, Walker is a qualified nutritionist who has followed a keto diet for 13 years or so.

“All the scientific studies will show that following a keto diet will raise cholesterol levels. But is cholesterol the one to be worried about? Or is it your blood sugar levels and your body fat percentage and your blood pressure?” Walker argues.

“In the keto world, we kind of follow the science that the saturated fat and the cholesterol debate is pretty much flipped on its head. Cholesterol is not the issue, it’s the sugar in your blood.

“The bigger part of [the debate] keeping the keto trend alive is the sugar control side of it. What we’ve noticed is the increase in pre-diabetes and type-2 diabetes in the UK is actually driving growth in the keto category.”

Diabetes debate

Walker’s suggestion that diabetics are attracted to the keto diet as a means to tackle the condition is a view shared by Moring but not one advised by Diabetics UK. The charity emphasises it doesn’t “recommend the keto diet for treating diabetes because there is not enough evidence to say it is safe or effective”.

Diabetics UK explains in its online guidelines that increased ketone levels are potentially harmful for people with diabetes.

“When ketones build up in the blood, they can become acidic and lead to something called diabetic ketoacidosis (DKA). This can be life-threatening…If you have type-1 diabetes, you’re more at risk of experiencing DKA than people with other types of diabetes. But if you have type-2 and use insulin then you should still look out for the signs of DKA.”

Moring, however, says many people suffering from diabetes or those that are pre-diabetic or just obese, turn to keto because they are reluctant to go on medication as part of lifestyle adjustments. It may also appeal to consumers generally seeking more of a “reset”.

“There are times in the year when it’s useful, but not necessarily every day, all day, forever. You can come in and out of ketosis as well,” she says.

Moring explains her interpretation on the rise in obesity and diabetes, and the reasons some people may be turning to a keto diet.

“Our insulin resistance is continually increasing because what we’re doing is eating significantly more sugar than we would have done ancestrally, 100 years ago, or even 1,000 years ago.

“We’ve raised that baseline level up and this is where diabetes is coming from because you have that sugar, you’re eating it as cereal for breakfast, for example, a massive spike [in sugar]. Or even a smoothie – a lot of them are really high in sugar, you get that massive spike, you crash, and then you eat more.

“So you’re bringing your baseline up and if you do that every day over 20, 30, 40 years, that’s where we’re seeing issues.”

As well as aiding diabetics, Walker suggests the keto diet provides more energy, improves sleep and hormonal health, and is also beneficial for hypertension and neuro-degenerative diseases.

She describes her discoveries during her four-year nutrition therapy diploma: “Ultimately, what it showed was that if we eat the way our bodies are designed to eat – omnivorous but mostly animal-based foods that are mostly hunted and gathered – essentially what you’re left with is a ketogenic diet.

“When I worked with clients with the diet, the results were astounding and it wasn’t just weight loss, it was digestive health, reproductive health, hormone health, and all of that.”

Detox pain

Walker, however, admits keto is not for everyone, for example as a long-term dietary regime for losing weight.

“Those that are doing keto for dietary reasons, they tend to come in and get back out again. Some of them just don’t find it sustainable, as with most of the diets.”

Moring explains it takes determination and perseverance to get through the initial weeks of conversion, and with some pain – perhaps why keto as a diet regime has attracted criticism.

“I think it gets a bit of stick because you have this big detox at the beginning of going from the normal Western diet into ketosis, and you can feel shit for two or three weeks.

“But when you come through the other side of that and your body’s got off the reliance on sugar and poor quality food, you do feel amazing. But a lot of people don’t make it through that first few weeks because they want to be amazing instantly – that quick fix kind of culture.”

Medlin says there’s a way of “softening the blow” of a low-carb diet by including whole grains, pulses and lentils, and suggests gut health is becoming the focus of the day rather than keto. And she takes a swipe at food manufacturers jumping on the keto bandwagon with additive-heavy foods.

“I think one of the problems with these kinds of diets is the food industry gets involved and you end up having loads and loads of processed keto foods, which of course are not good for you at all – sweeteners and flavourings and colourings and all sorts of things that we don’t want in our bodies.

“Salts and things like that make them palatable, and that’s where you can end up undoing any potential benefits quite quickly.”

Benefits for Alzheimer’s, Parkinson’s?

As with many of the claims linked to a keto diet, Medlin disputes the connection with treating illnesses such as Parkinson’s and Alzheimer’s as suggested by healthcare body the Mindd Foundation in Australia.

Mindd notes: “In AD [Alzheimer’s Disease] low-glucose metabolism in the brain precedes cognitive decline and memory loss. The impaired glucose uptake present in AD may be supported by ketones, as beta-hydroxybutyrate and acetoacetate are the brain’s alternative energy sources to glucose.

“These ketones are able to act as energy sources for the brain, as the brain receives approximately 65% of its energy from ketone bodies when blood glucose levels are low.”

And for Parkinson’s, Mindd suggests: “It is hypothesised that the ketone body beta-hydroxybutyrate elicits a protective action on neurons and prevents neuro-degeneration in PD.”

Similarly, for the potential treatment of Multiple Sclerosis (MS), Mindd adds: “Due to altered and impaired glucose metabolism, increasing energy supply through ketosis could potentially be beneficial. There is also a lower uptake of glucose in the brain of MS sufferers, and providing the brain with an alternative source may reduce the rate of degeneration.”

However, Medlin argues “there’s no convincing data” when it comes to keto being beneficial to Alzheimer’s or Parkinson’s sufferers.

“Keto can be a tool that supports them in their weight management but it’s certainly not the best tool or the safest tool or a good long-term strategy. There’s no data or anything that supports its use, it’s just not something that’s accepted in research or clinical practice.”

Where’s the ketogenic diet headed?

As a purely dietary regime, Victor Martino, a food consultant and founder of Third Wave Strategies in the US, says keto “seems to be as popular as ever” but emphasises it remains specialised and niche.

Creating brand new keto diet-focused packaged goods products isn’t something I see as a good idea

Victor Martino

“Keto isn’t going away and it offers opportunity for brands, particularly in the area of taken products,” he says but adds with a cautionary note: “Creating brand new keto diet-focused packaged goods products isn’t something I see as a good idea, though, unless the niche is a new and potentially large one.”

While Walker at The Keto Collective suggests more studies are coming out that will likely promote the benefits of a keto diet beyond weight management and sugar control, nutritionist Medlin has reservations.

“I don’t see any pros apart from for a small group of people. It might help with weight loss but the long-term health implications of that are likely to be worse than if they just looked after their body in a healthful way, irrespective of weight loss,” Medlin argues.

Catalina Crunch, meanwhile, is out to convince consumers of the benefits of a low-carb and low-sugar diet but with less of a focus on keto and its high-fat consumption bias.

Given the “obesity trends” in the US, van Ark says Catalina is “trying to drive real change in how people feed themselves and feed their families and to [attest] the growth in diabetes and heart-related diseases”.

He adds: “Whenever you hear the term diet people automatically assume or the consumer assumes that they’re giving up something. That’s the challenge.”