The hot new diet downplays carbohydrates in favor of lots of fats—from foods like avocados and cheese. Without the carbs, say proponents, the body burns stored fat instead through a process called ketosis.

There are some studies that back up the theory. One monitored 83 obese patients over a 24-week period, finding significant weight loss and lower cholesterol levels. Experts do say you should check with your doctor before embarking on the keto diet, however.

Keto’s not a diet for people who aren’t dedicated. While it doesn’t ban carbs outright, it is very strict on their consumption. Instead, it encourages “liberal” amounts of avocado (sorry not on toast), cheese, walnuts, almonds, and grass-fed beef.

None of those foods are cheap. Avocado prices have surged in the past year. Grass-fed beef, while it might be easier to find in the coming months, is hardly inexpensive, too. And the cost of quality cheese and nuts can run the gamut.

Still, that’s not discouraging people. And the growing obsession with the keto diet is giving birth to a cottage industry, as companies try to cater to Keto enthusiasts. Ancient Nutrition, for example, has invested $103 million to expand its line of products that cater to the market.