Fasting diets are way old, dating back to at least 500 B.C. Of course, back then, people didn't do them so they'd be able to fit into their summer tunics at the be-there-or-be-square Golden Stag Viking Blood Bath Festival. Instead, they used them to treat epilepsy (1).
Early 20th century physicians took note of their ancient predecessors and invented the carb-restricting ketogenic diet, reasoning that it would mimic the metabolism of fasting and help their pediatric patients who were suffering from epilepsy. They were right.
There were, however, a few people who were concurrently using the diet – or at least versions of the diet – for non-epileptic purposes. Among them was a guy by the name of Atkins who, in 1972, released his now famous, eponymously named carbohydrate-restricted weight-loss diet.
(While the Atkins diet isn't a true zero-carb diet, you're instructed to reduce carbs to a ketogenic level in the initial stages.)
The keto or keto-like diets didn't trickle into the world of athletics, though, as best as I can tell, until the early 1990's when cyclical ketogenic diets (CKD) and Dr. Mauro DiPasquale's "Anabolic Diet" started to pop up in the newsstand muscle mags.
The diets consisted of approximately 60% fat, 35% protein, and only about 5% carbs, which is pretty much what today's keto dieters strive for.
The trouble is, there's an epic fail going on. Except for the epileptic children who used the keto diet and were extensively monitored by doctors, hardly any of the keto pioneers – or its current practitioners – are actually in ketosis.
When you deprive your body of carbohydrates (sugar), it's eventually depleted of glucose and its stored form, glycogen. The body is then forced to make "ketone bodies" from fat to replace the glucose and glycogen as a fuel source.
It's a biochemical, starvation-fighting marvel and it can come in real handy when your wicked aunt has locked you in a broom closet for weeks with nothing to eat.
Hitting ketosis through voluntary dietary interventions, though, is pretty tricky. To ensure that it happens, you'd have to get 80 to 90% of your calories from fat, which is easy if you live in arctic climes and you never miss Sunday brunch at Nukilik's All-You-Can-Eat Eskimo Buffet.
For the rest of us, it ain't so easy. All that saturated fat maybe ain't so healthful, either. But many keto dieters will say that you don't need that much fat. They figure that as long as you keep your carbs below 20 or 30 grams and get the rest from protein, you'll be a card-carrying member of the keto clan.
Not so fast, keto boy. For one thing, all it takes to slip out of ketosis is an apple that's a little too big, a spoonful of hidden sugar in a sauce, or a morsel of matzo in your meatloaf. Very few people can attain and maintain this level of monastic dietary severity for very long.
But carbs aren't the biggest problem. That honor goes to protein. Keto dieters, especially athletes who are keto dieters, eat a lot of protein for a few reasons:
- To presumably guard against muscle loss.
- To hopefully build muscle at the same time (yeah, right).
- Or because eating nothing but blubber gets disgusting after a while, and what else is there to eat once you've eliminated carbs?
These high-protein eaters are missing a piece of information, though. When the body isn't getting a sufficient amount of carbs from fruits, vegetables, or grains, it starts breaking down the amino acids in dietary protein to make glucose, thereby knocking them out of ketosis.
While there are some people who are no doubt able to slip into ketosis and stay there by living a butter and gravy lifestyle, most people who think they're in ketosis are just following a more extreme version of a carb-restriction diet.
They'll invariably lose weight, but it's not exclusively because the body is burning through its fat reserves. More likely, it's because of the following reasons:
- Any time you start paying attention to what you eat, you invariably lose weight. It's the "secret" to all diets.
- For every gram of carbohydrate (glycogen) stored in your body, there are 2 to 3 grams of water associated with it, so keto diets make you lose a lot of water weight.
- Keto diets can result in loss of muscle weight if calorie intake isn't sufficient.
- Keto diets dramatically increase insulin sensitivity, causing insulin to become your fat-loss friend instead of a fat-loss enemy.
True keto diets are extremely hard to maintain for long periods of time, but most keto dieters are going through the motions without actually being in ketosis. All they're doing is following a more extreme version of a carb-restriction diet.
Either way, they'll invariably lose weight, but most will likely gain much of it back if/when they start living/eating like the rest of God's children.
Regardless, given that the diet disproportionately cannibalizes protein, it should be avoided by anyone who's involved in the muscle game.
- Wheless JW. "History of the ketogenic diet," Epilepsia. 2008 Nov;49 Suppl 8:3-5.