It has long been accepted that carbs are essential for endurance sports and general functioning, but nutritionist Dr. Mike Roussell says you can thrive on a very-low-carb, or even a no-carb, ketogenic diet.
"You could cut out carbs and rely on fats alone for fuel, and it is completely safe," Dr. Roussell told Shape. "Certain nutrients in your diet are absolutely essential, including a couple different fats, a handful of amino acids, and lots of vitamins and minerals. No sugars or carbohydrates make the 'must-eat' list."
This may seem like a shocking revelation since the U.S. government has prescribed a high-carb, low-fat diet for the past 40 years, but Roussell joins a growing list of medical experts who say carbs are not an essential part of our diets.
When you deprive your body of carbs, it uses alternate energy sources, namely ketones (a byproduct of excessive fat breakdown). This adaptation enables you to function on a very-low-carb, or even a no-carb, diet.
"These diets are very effective for fat loss, reducing certain risk factors for heart disease, and treating diabetes and epilepsy," said Roussell, nutrition advisor for Men's Health magazine and author of The 6 Pillars of Nutrition.
"Your brain may have switched to this alternate fuel source without you even knowing it if you have ever eaten a very low-carb or ketogenic diet, where you consume 60% to 70% of your calories from fat and only 20 to 30 grams of carbs per day."
On a ketogenic diet, carb intake is drastically reduced, usually to less than 70 grams a day, while fat consumption is elevated, and protein intake is moderate. A common complaint is that ketogenic diets are unpalatable and difficult to stick to, which is why most people don't follow them, but they've been touted for promoting rapid weight loss, and preventing diabetes, heart disease, epilepsy, depression, and Alzheimer's.
Ketogenic Diet Can Prevent and Starve Cancer
Cancer scientist Dr. Dominic D'Agostino recently told me the ketogenic diet can prevent and manage even aggressive cancers because cancer is a metabolic — not a genetic — disease.
"Most cancer scientists have historically thought cancer was a genetic disease, but only 5-10% of cancer is hereditary," said Dr. D'Agostino.
All the cells in our body can use both fat and glucose (a carb), but cancer cells thrive on glucose and cannot survive on ketones. So by limiting carbohydrates (which turns into glucose inside the body), we can starve cancer cells.
The ketogenic diet is becoming increasingly popular as saturated fat is being embraced by the medical community as healthy. In March 2014, Cambridge University scientist Dr. Rajiv Chowdhury and his colleagues concluded that unprocessed saturated fat is healthy after reviewing data from 72 published studies of more than 600,000 people from 18 countries.
“It’s not saturated fat that we should worry about," Dr. Chowdhury wrote in the Annals of Internal Medicine. "It’s the high-carbohydrate or sugary diet that should be the focus of dietary guidelines. If anything is driving your low-density lipoproteins in a more adverse way, it’s carbohydrates.”
Chowdhury is not the only heart doctor who holds this opinion. Cardiologist Dr. William Davis, author of Wheat Belly, said a low-carb, high-fat, wheat-free diet reverses diabetes and prevents heart disease.
And neurologist Dr. David Perlmutter, author of Grain Brain, said the ketogenic diet prevents — and even reverses — Alzheimer's disease and ADHD. "Carbs are devastating for the brain," Perlmutter told me. "Even slight elevations in blood sugar have been shown to increase the risk of Alzheimer’s."
'For 98% of Human History, We Ate Low-Carb'
Dr. Jeff Volek, a professor at the University of Connecticut, is a pioneer in the low-carb, high-fat (LCHF) diet movement. Dr. Volek, author of the Art and Science of Low Carbohydrate Living, said the ketogenic diet is actually our natural diet.
"For about 98% of human history, we've been eating low-carb," said Dr. Volek. "We evolved in a state of nutritional ketosis."
Volek pointed out that the low-carb ketogenic diet has already proven effective for producing rapid weight loss, reversing type 2 diabetes and preventing heart disease. "There are very few people that a ketogenic diet could not help," he said.
Volek has followed a ketogenic diet (consisting of 70% fat, 5%-10% carbohydrate, and 15%-20% protein) for the past two decades, and credits it for his excellent health. "It was nothing short of an epiphany when I changed to a ketogenic diet," he said. "I felt better, more satiated, and had more consistent energy."