With grains, most fruits, and many vegetables off the menu, your digestive tract will bog down. “It’s really hard to get adequate fiber eating that way,” says Notte. “A common side effect is significant constipation.” Not only is constipation unpleasant, but it’s also a sign that your gut isn’t happy. “Everything in the keto diet is low in fiber—and that does not support gut health.”
“When you’re on a restrictive diet, deprivation builds and builds, and when you finally give in and have something that’s not on your plan, you can overeat,” Notte says. This can lead to shame and guilt, she warns. “You think, well, I already blew it, so I might as well just eat it all,” she says. Occasional binge eating can, in turn, develop into a full-blown disorder called binge eating disorder for those who are predisposed to it, according to the National Eating Disorders Association. Check out the 10 surprising health benefits of keto.
Before starting, ask yourself what is really realistic for you, Mattinson suggests. Then get your doctor’s okay. You may also work with a local registered dietitian nutritionist to limit potential nutrient deficiencies and talk about vitamin supplementation, as you won’t be eating whole grains, dairy, or fruit, and will eliminate many veggies. “A diet that eliminates entire food groups is a red flag to me. This isn’t something to take lightly or dive into headfirst with no medical supervision,” she says.
In the world of nutrition, the ketogenic diet is enjoying its moment as diet du jour. Google trends show a sharp uptick in searches for the ketogenic diet since 2016. Almost 550,000 people subscribe to the r/keto subreddit. And when I searched #keto on Twitter, I found an endless stream of modified keto recipes and stories claiming successful weight loss.
Symptoms of the keto flu include headache, fatigue, dizziness, sleep problems, heart palpitations, cramps, and diarrhea. These side effects usually lessen and eventually resolve in about two weeks. (2) But to lessen the effects of any discomfort, simply consider slowly transitioning onto a ketogenic diet rather than rushing to change your eating habits. By slowly lowering your carbohydrate intake, while gradually increasing your intake of dietary fat over time, you can transition with less of a negative impact and potentially prevent the keto flu.
This means that if you have risk factors for heart disease — such as elevated cholesterol levels, high blood pressure (hypertension), or a strong family history of the disease — you should use caution when following this diet. The diet's heavy reliance on fat, especially saturated fat, can elevate cholesterol levels, further increasing your chances of developing heart disease in the future. (7)
The biggest lifesaver, though, came at dinnertime. While I'm okay with sticking to a routine during the day, my dinners have to be different each night. So rather than fall into a trap of Googling "Is fill-in-the-blank-food keto?" I turned to HelloFresh. The subscription meal company recently acquired Green Chef, a company that develops gluten-free menus for those following a keto or paleo plan. (Related: What's the Difference Between the Paleo and Keto Diets?) This means that three nights a week, I didn't have to think about whether the foods in my dinner had too many carbs or not enough fat, or go grocery shopping and spend hours reading nutrition labels. (You'd be shocked at how much sugar, a no-go on keto, is hiding in foods that have no need to be artificially sweetened.) All I had to do was pull the fresh ingredients out of the fridge, follow the recipe, and dig in.
A small Feb. 20, 2017, study looked at the impact of a six-week ketogenic diet on physical fitness and body composition in 42 healthy adults. The study, published in the journal Nutrition & Metabolism, found a mildly negative impact on physical performance in terms of endurance capacity, peak power and faster exhaustion. Overall, researchers concluded, “Our findings lead us to assume that a [ketogenic diet] does not impact physical fitness in a clinically relevant manner that would impair activities of daily living and aerobic training.” The “significant” weight loss of about 4.4 pounds, on average, did not affect muscle mass or function.
Temperatures are dropping fast, which means soup should be your new best friend. And when that soup is thick, rich, and high in protein and fat, it’ll really stick to your bones on a chilly night. This soup by Cast Iron Keto has only 6.7 grams of net carbs and tons of filling fats from the heavy cream and cream cheese. Add sliced jalapeño on top for a little kick.
In terms of weight loss, you may be interested in trying the ketogenic diet because you’ve heard that it can make a big impact right away. And that’s true. “Ketogenic diets will cause you to lose weight within the first week,” says Mattinson. She explains that your body will first use up all of its glycogen stores (the storage form of carbohydrate). With depleted glycogen, you’ll drop water weight. While it can be motivating to see the number on the scale go down (often dramatically), do keep in mind that most of this is water loss initially.