US medical experts have released a report to counteract the hype surrounding the popular ketogenic (keto) diet, claiming the enthusiasm surrounding the diet far exceeds any evidence supporting its supposed health benefits.
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What is the keto diet?
The ketogenic diet has surged in popularity following a recent trend towards low-carbohydrate diets, such as the Atkins and Paleo diets. A keto diet encourages its followers to forgo nearly all carbohydrates - no pasta, no fries, no pizza! - and avoid excess protein.
The result? A very high-fat diet. The drastic reduction of carbohydrate intake, relying predominantly on calories from fat, puts the body into a metabolic state called ketosis.
Ketosis supposedly makes the body more efficient at burning fat for energy - hence, keto's claim to fame as a weight-loss wonder was born.
The diet is said to have gained traction after the "failure" of popular low-fat diets "to curb the obesity epidemic and its associated increase in type 2 diabetes," says the report.
Examples of keto staples include shellfish and fish, nuts, meat and poultry, eggs, cheese, coconut oil, avocado, spinach and broccoli.
Is the keto diet effective for weight loss?
Despite the hype and plethora of success stories, the answer is far from 'yes'.
A meta-analysis of 32 controlled-feeding studies found that fat loss and energy expenditure were actually greater with low-fat diets instead of keto diets. Researchers also found keto to be associated with less than a kilogram of additional weight loss over low-fat, high-carb diets.
"This difference may not be clinically significant," says the report.
Furthermore, the foundation of successful weight loss is expending more energy than consumed to create a caloric deficit. This is the basic fact of weight loss, and proves true regardless of the individual's diet.
"Any diet that results in weight loss does so because it reduces calorie intake. The ketogenic diet, when used for weight loss, is no different," says the report.
Is the keto diet effective in treating type 2 diabetes?
One well-publicised study says yes, the keto diet is beneficial for those with type 2 diabetes - unfortunately, there is a 'but' coming.
The report says to treat these findings with caution - the group was self-selected, and "received intensive technological and behavioural support not offered to the control group". This indicates that the popular study may not have been a fair test.
"A meta-analysis of randomized long-term studies comparing the ketogenic diet with low-fat diets for weight loss reported no difference in glycemic control among persons with type 2 diabetes.
"There is little if any evidence that ketogenic diets specifically improve carbohydrate intolerance... unlike other dietary approaches in which glycemic control is improved despite the consumption of healthful carbohydrate-rich foods, such as legumes, whole grains, and fruits," the report claims.
What are the risks of eating a ketogenic diet?
There is no 'one size fits all' in the world of dieting, and what works for one person may cause havoc for another. The report acknowledges constipation, halitosis, muscle cramps, headaches, diarrhoea, restricted growth, bone fractures, pancreatitis, and multiple vitamin and mineral deficiencies as possible documented side effects of ketogenic dieting.
The report also draws attention to the diet's lack of unrefined, high-fibre carbohydrates such as fruit, legumes and whole grains - "some of the most health-promoting foods on the planet".
The claims surrounding keto's dietary treatment of obesity and type 2 diabetes have limited scientific backing - and its risks may be overlooked by excited keto converts.
"Physicians and patients should continue to appraise the benefits and risks of the ketogenic diet," says the report.
"In accordance with the evidence, not the hype."