What is it? A high-fat, low-protein and low-carb way of eating. In the 1920s, it was used to treat epilepsy and other seizure disorders. In the late 1990s, it gained prominence once again, in part because of the Meryl Streep movie “First Do No Harm.” Interest has been on the rise since then, not only to control seizures but also to help with weight-loss resistance, cognitive function, fatigue, energy, mood, blood sugar balance and management of chronic conditions, such as Type 2 diabetes. NBA star LeBron James claims to have lost 25 pounds and improved his athletic endurance by going “keto.” 

How do I do it? A true ketogenic diet is a medical treatment and should always be prescribed and monitored by a licensed health care provider. It also requires very precise carbohydrate counting and macronutrient tracking. You can get many of the same benefits by adopting a modified ketogenic diet. 

What does it involve? The key is intermittent fasting, or going from 12 to 16 hours in a 24-hour period without eating, four to five days a week. (Don’t panic. This can include time spent sleeping.) When you do eat, you stick to whole foods — lots of healthy fats, protein and as many non-starchy vegetables as you can manage. 

My experience: Because I hate the idea of fasting, I dreaded my keto experiment. To make the fasting doable, I had to turn it into a game. Every day, I would see if I could go without food for longer than the day before. (I made it 12 hours and 15 minutes yesterday. Can I go 12 ½ hours today?) Soon my competitive desire to best my fasting time outweighed my usual laser focus on food. 

What happened? I started a modified keto diet to help with my blood sugar, a chronic problem for me despite the fact that I gave up refined sugar long ago. After two months of the diet, my blood sugar dropped significantly. But there was a more noticeable — and unexpected — benefit: I had increased mental clarity and concentration. It’s like someone cranked my brainpower dial to 11. I wasn’t concerned with weight loss, but even so, I’ve thinned out around my waistline. In general, I feel lighter and as if somehow all my body’s systems are running more efficiently. 

Any cautions? Extending the time between meals is generally considered safe, but anyone with a chronic condition or blood sugar or thyroid issues should consult a trusted health care provider before adopting this kind of diet. 

Laine Bergeson is a functional medicine health coach and health journalist.