Not a day goes by that I don’t hear, read, or field a question about the keto diet. And no wonder: There’s a ton of hype about the dramatic results.
The keto diet (short for ketogenic diet) is a high-fat, low-carb eating plan. By depriving your body of carbohydrates, its preferred source of energy, you force it to use fat for fuel instead. That causes the liver to make ketone bodies, which your cells can use for energy. Being in that prolonged state of using fat for energy is called being in ketosis.
When it comes to weight loss, it’s effective. That’s because the body burns a lot of calories turning fat into energy, and dialing carbs way back leads to a quick drop in water weight. Your appetite is also dulled from eating so many high-fat foods, and you’re eliminating a lot of foods (and dramatically narrowing the variety of foods you eat), which will all decrease how much you eat.
But there is a cost. In fact, there are a handful of things that tend to surprise people when they learn more about the keto diet. So if you’re thinking about trying it, here are some things you should know:
It’s not a high-protein diet: Some people assume that because the keto diet is low-carb, it’s a meat-lover’s dream. But the diet doesn’t actually call for a lot of protein. The typical breakdown is 75 percent fat, 20 percent protein, and 5 percent carbs. So while there’s room for steak, your primary focus is fat, such as butter, nut butter, and coconut oil. And it's still unclear whether there are long-term health risks of eating so much fat every day, especially saturated fat.
Vegetarians may struggle: Though it’s not a high-protein diet, vegetarians may still find it hard to meet their protein needs without off-limit foods like beans and grains. And since some veggies contain carbs, you can’t eat them in endless amounts on the keto plan.
Most fruit is a no-no. Beyond small portions of berries, fruits aren’t allowed because they’re rich in carbs. To stay in ketosis, you may only be able to eat roughly 20 grams of carbs a day—and one large apple has 25.
You may get constipated. By nixing foods like whole grains, beans, and fruit from your diet, you’re cutting out rich sources of fiber. Other common side effects: Low blood sugar and a “fuzzy headed” feeling from the lack of carbs.
It wasn’t supposed to be a weight loss diet. The ketogenic diet was developed nearly a century ago to treat seizure disorders such as epilepsy in children.
It can be socially isolating. Family dinner, happy hour with friends, parties, and meals at other people’s homes are tough to manage on keto. And since weight loss hinges on staying in ketosis, hopping on and and off for parties, dinners, or simply to have a sandwich on bread, you’ll kick yourself out of ketosis.
The benefits are overhyped. Yes, the keto diet will likely lead to weight loss if followed. But all the proclamations about keto curing acne, slowing signs of aging, and preventing cancer? The evidence is just not there, so take them with a big grain of salt.