Thinking about going keto? A ketogenic diet could help you drop pounds faster than traditional weight-loss plans, research shows. And plenty of proponents say going super low-carb boosts their energy and helps them think more clearly.
In other words, giving this trendy eating style a try could deliver big benefits. That is, if you know what you’re doing. There are lots of ways a keto diet can go wrong—and when that happens, you might find yourself feeling pretty crappy. Here are six common mishaps keto newbies make, plus what you can do to steer clear.
1. Not anticipating an adjustment period.
The first few days on a keto diet can feel a lot like having the flu. It’s common to get slammed with a headache, weakness or fatigue, muscle cramps, nausea, and diarrhea or constipation.
Here’s why: Your body enters a state of ketosis once your carb intake drops below around 50 grams a day. When that happens, your cells switch from burning glycogen (energy from carbohydrates) for fuel to burning ketones, an alternative source of fuel that the liver makes from fat. “You’re asking your cells to do something they aren’t used to doing,” explains Robert Santos-Prowse, RD, author of The Cyclical Ketogenic Diet. “When you suddenly deprive them of the fuel they’re used to using, there may be a period of sluggishness or brain fog.”
Another reason you might feel like garbage? Transitioning to keto may also cause your body to shed more water (read: you’re peeing more). “Especially in the first week of a low-carbohydrate diet, your body is shedding a large amount of stored water as it breaks down glycogen in your muscles and liver,” says Georgie Fear, RD, author of Lean Habits for Lifelong Weight Loss. “Just like an athlete who sweats heavily loses a large number of salts and minerals, a person excreting large amounts of fluids can also become dehydrated or low on electrolytes like sodium and potassium.”
2. Skimping on the water.
It’s always smart to stay hydrated—but since you’re losing all those extra fluids and minerals, you really want to drink up while you’re eating keto. “Make sure to drink at least 64 ounces of water a day,” Fear says. And if you’re still thirsty, drink more.
Make an effort to replenish those lost electrolytes by eating plenty of potassium- and magnesium-rich foods. Think avocado, tomato sauce, spinach, salmon, and nuts. As for sodium? “Don’t worry about adding extra salt to your food since most of us get plenty,” Fear says.
3. Going all meat, all the time.
Think keto diets are all about the protein? Nope, that’s wrong. Eating keto is actually all about the fat. “A ketogenic diet essentially swaps the percentages of fats and carbohydrates,” Santos-Prowse says. That means you’ll get up to 80 percent of your calories from fat and five to 10 percent from carbs. The remaining 15 to 20 percent should come from protein, which is about the same as standard higher-carb diets.
In other words, the goal isn’t to pile your plate with steak or chicken. So what should you be filling up on instead? At each meal, aim for three to four ounces of lean protein (like lean beef, fish, or pork) cooked in butter or oil, along with a half-cup of non-starchy veggies (like leafy greens, broccoli, or cauliflower) and a serving or two of healthy fat (like a tablespoon of olive oil or 1/4 medium avocado), Santos-Prowse suggests.
4. Forgetting about fiber.
If you suddenly find yourself backed up and bloated after a few days of eating keto, you’re not alone. Putting all the focus on fat can make it easy to forget about that other important F: fiber. Add even a touch of dehydration to the mix and you’re looking at the potential for a bad case of constipation.
Since high-fiber foods like whole grains, beans, and fruit also tend to be high in carbs, you’ll need to find other ways to get enough roughage. Eat as many high-fiber vegetables as you can within your carbohydrate limit, Fear says. (Good ones include artichokes, broccoli, and Brussels sprouts.) Make avocado a mainstay too—it’s one of the few fat sources that also provides fiber. And remember to drink that water.
5. Letting your carbs creep up.
Craving a cookie or a slice of pizza? It’s totally fine to have higher carb fare once in a while… after your body has adjusted to your new eating style. Research suggests that it takes 30 to 60 days for your cells to fully adapt to using fat for fuel instead of sugar. Up your carb intake before that happens, and there’s a good chance you’ll cycle in and out of ketosis—and get slammed with nasty keto flu symptoms each time.
The lesson: Keep your carbs below the magic threshold for at least a month or two before having a carby treat. “If you stick to a ketogenic diet for long enough to become well adapted, your body will easily burn fat or carbohydrates for fuel and switch between the two without much effort,” Santos-Prowse says.
6. Going it alone long-term.
Eating keto can help you drop pounds quickly. But some experts are wary about whether it’s OK to stick with the diet for the long haul. “We don’t have long-term data to tell us what happens to humans when they are in a state of ketosis constantly over long periods of time,” says Julie Stefanski, RDN, LDN, a spokesperson for the Academy of Nutrition and Dietetics.
Based on common sense, though, if you decide to stay in ketosis for a long period of time, you could miss out on important nutrients that some higher-carb foods offer.
So if you plan to live the keto lifestyle, it’s a good idea to talk with a registered dietitian, Stefanski says. They can assess your eating plan to fill any nutritional gaps and help keep possible health problems at bay.