Modern physicians introduced the ketogenic diet as a treatment for epilepsy in the 1920s because it mimicked fasting. It was widely used as therapy, though it declined dramatically with the coming era of antiepileptic drug treatment. However, the diet has a moment again as it's made a roaring come back in the last decade.
The resurgence of keto (shorthand) is born out of our enduring desire to adhere to diets that help manage health concerns and improve our quality of life. This high-fat, deficient carbohydrate diet mirrors Atkins in its willingness to flip our macronutrient script. The positive news in implementing this strategy is that you can trigger your body to use different energy pathways by getting more calories from fat. Instead of carbs for energy, the body burns fat, entering a state called ketosis. Ketosis has proven to protect our brains, as seen in people with epilepsy having fewer seizures after following the diet. Additional research suggests it is effective in controlling blood sugar levels among people with diabetes.
The unfortunate news in the case of keto is there's very little evidence to show that this type of diet is safe or effective over the long haul--save for epilepsy. It's an unbalanced diet, plus the side effects of constipation, headaches, bad breath, and more can be a bit scary as well.
The keto diet is undoubtedly popular. I just saw three keto magazines next to each other at the airport newsstand. The likely reason for its mainstream success is the rapid weight loss seen on the front end of starting the diet. But, like many adaptive changes that swing the pendulum early on, it comes swinging back the other way eventually.
My bottom-line advice
Eat balanced with natural foods.
Try intermittent fasting as that's what the original physicians were trying to achieve (actually mimic) with the epilepsy patients.
And take long walks.