© Getty News "Personal testimonials of keto 'success' continue to flood the internet, but this doesn't equate to reliable and trust-worthy scientific evidence," said one expert.
In a recent ranking of the best and worst diets by the US News & World, the ketogenic (keto) diet was ranked one of the worst out of 35 diets.
And yet, according to a recent survey of registered dietitians, the keto diet remains the most popular in the United States.
Fast, short-term weight loss is probably the reason the keto diet remains so popular, registered dietitian Shahzadi Devje told Global News.
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"Any diet that's trendy, promises to make you lose weight quickly and look fit will get your attention," she said.
"Personal testimonials of keto 'success' continue to flood the internet, but this doesn't equate to reliable and trustworthy scientific evidence."
By mandating foods high in fat and low in carbohydrates, the keto diet sends the body into a state of ketosis.
Once there, the body burns fat instead of sugar for energy. Advocates claim the diet promotes weight loss and boosts energy, but experts on the US News & World Report panel are worried about its potential negative effects.
The organization said each of the diets was given ratings out of five in the following categories: "how easy it is to follow, its ability to produce short-term and long-term weight loss, its nutritional completeness, its safety and its potential for preventing and managing diabetes and heart disease."
The keto diet did not score well in any of those categories. In the safety category, it was given an overall rating of two out of five due to its high fat content. One expert warned that those with severe diabetes, kidney disease and heart disease should not follow this diet.
The highest rating given to the keto diet was in the category of short-term weight loss, for which it received a 3.8 out of five. Experts on the panel noted "the low-carb plan is generally a quick, effective weight-loss strategy."
That's exactly why nutrition experts like Dr. David Jenkins worry about the keto diet: it may promote quick weight loss, but that doesn't necessarily mean it's a healthy way to live.
Jenkins, a professor of nutritional science in the faculty of medicine at the University of Toronto, fears the diet cuts out too many healthy foods in addition to unhealthy ones.
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"You've got carbs on the positive side of health and on the negative side of health," he said. "If you just cut out the lot, you're cutting out the good, the bad and the ugly."
Registered dietitian Lauren McNeill agrees.
"The greatest risk I see to a keto diet is cutting out or severely reducing the foods that we know from decades of research have extensive health benefits, such as whole grains, legumes, fruits and certain vegetables," she said.
"Some of the healthiest populations that we know consume these foods on a regular basis, and there's no shortage of research showing their benefits on potential risk reduction of cardiovascular disease, certain types of cancer, Type 2 diabetes and even weight management."
The only time a doctor would recommend the keto diet
Thus far, the only proven clinical use for the keto diet is in children with epilepsy.
"This diet may be quite useful if the drugs aren't working well, but these are controlled conditions," Jenkins said.
Devje supports this claim.
"There's substantial evidence showing that a ketogenic diet reduces seizures in children," she said.
"There is some thinking that perhaps such benefits may extend to other brain disorders (like Parkinson's, Alzheimer's, multiple sclerosis) ... but I was not able to find any human studies to support recommending the keto diet to manage these conditions," she said.
It's important to note that in children with epilepsy, there can be adverse side effects.
"Their fibre may be down (because fibre is commonly found in carbohydrates), which can lead to constipation," said Jenkins.
The case for ditching diets altogether
The healthiest diets, as determined by health and nutrition experts in the US News & World ranking, were the Mediterranean diet, the DASH diet and the flexitarian diet.
However, registered dietitian Stephanie Hnatiuk doesn't consider the keto diet more or less "dangerous" than other restrictive ways of eating.
It can be extremely challenging to stick to the keto diet for longer than a few months, which can lead people to what Hnatiuk calls "yo-yo dieting."
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"A person loses some weight on a diet, is unable to keep up with it and ultimately quits the diet, leading them to regain the weight they lost and often more," she told Global News.
Instead, Hnatiuk encourages her clients to abandon diets altogether.
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"We need to start thinking about our overall dietary patterns in a more long-term, sustainable way," she said. "Avoid the short-term diets, challenges or things that promise a quick fix. Instead, simply make small changes to improve our eating habits."
This can include reducing added sugars, cooking more meals at home and adding more fruits and vegetables to your diet.
"Over time, these [will benefit our health more than] an endless stream of short-term fad diets," said Hnatiuk