You'll likely drop a few pounds at first, but this RD still thinks you should stay far away from keto.

Lisa Valente, M.S., R.D.
January 06, 2020

When I first learned about the ketogenic diet over 10 years ago—in a clinical setting, as a way to help kids with epileptic seizures—I would have never (like, never ever) guessed it would become one of the top weight-loss diets. But here we are, in 2020, and the keto craze rages on.

In case you are unaware, the ketogenic diet is an ultra high-fat, low-carb style of eating. No foods are off limits, but you're supposed to keep your carbs under 5 percent of your total calories for the day or around 20 grams depending on your energy needs. For reference, one medium banana has 27 grams of carbs. Really, any foods that have more than a few grams of carbohydrate are difficult to fit in—it doesn't take much to get to 20 grams. That means bacon and cheese are in, apples and bread are out. (Learn more about all the foods you can and cannot eat on a ketogenic diet.) The idea is that your body enters ketosis, where it's burning fat (and breaking down your fat into ketone bodies) instead of carbohydrates. Many people who eat a low-carb diet aren't able to maintain ketosis, or stay there for very long, because it's hard to go that low in carbohydrates.

It was recently voted the second worst overall diet by U.S. News & World Report, largely because there isn't any science to back it up and it's not sustainable to follow. Although, it was also ranked as the number two diet for quick weight loss because people do lose weight on keto. When you cut out entire food groups and nutrients, you typically fall into a calorie deficit and your body will likely drop pounds (a mix of water weight and your fat stores shrinking).

Getty Images / Ralph Smith

This quick weight loss is what makes keto so popular. And while it may be tricky to get the hang of things at first, the rules are fairly straightforward. Answering one question tells you whether or not you can eat something, "Does this food have carbs?" It's easy enough and you'll lose weight—so why am I on the anti-keto bandwagon?

For one, I'm hesitant to recommend any plan that cuts out entire food groups. When you're not eating grains, and seriously limiting your intake of fruits, vegetables and dairy items to keep carbs low, it's very easy to miss out on key nutrients. Fiber, vitamins, minerals and antioxidants are all found in carbohydrate-rich foods. It's one reason why the keto flu is so common (learn more about other not-so-sexy side effects of the keto diet). Your electrolytes (sodium, potassium, magnesium) tend to drop as your body gets used to ketosis and you've cut out of a lot of the foods that deliver those minerals. While you can find electrolytes in certain low-carb foods (potassium is in salmon, avocado and spinach), you need to put some thought into it. Plus, have you ever had the flu? It stinks. Why would you want to follow an eating plan that may give you those same feelings?

And while you may think eating avocado omelets and cheeseburgers (hold the bun, ketchup and fries) is awesome, at some point you'll probably start to miss foods like cookies, bread, pasta, pineapple and ice cream. Imagine, no more birthday cake for the rest of your life! Not being able to go out to dinner without figuring out a low-carb option first (and not being able to have onions with your fajitas). Saying no to fruit salad because it "doesn't fit in your diet." It's hard to sustain keto for a long time and it's hard to do it without feeling deprived. As soon as you say no to certain foods, your body wants them more. Avoiding carbs means bagels, pizza and brownies are going to look extra appealing and then when you do go back, you're more likely to binge on those foods. Like with any diet, the weight you lost will likely come back.

The only thing I like about keto (besides that it may therapeutically help people with serious medical conditions) is that it may help people be less afraid of fat. There are plenty of healthy high-fat foods—avocados, nuts, nut butters, seeds, olive oil, olives—that people are still afraid of, thanks to the low-fat craze of decades past. Go ahead, eat the fat! Just also eat the carbs (and protein). Balance, people.

Your body wants to run on carbs. Your brain, in particular, runs on glucose. When you don't have any carbs to use, your body has to enter ketosis, in order to fuel your brain (which can survive on ketone bodies). I like to think of ketosis more as a survival mechanism than a way to lose weight.

Welcome to The Beet. A weekly column where nutrition editor and registered dietitian Lisa Valente tackles buzzy nutrition topics and tells you what you need to know, with science and a little bit of sass.

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