Symptoms such as fatigue and constipation are common when starting the keto diet.
However, if you stick to the diet, you will have more energy and fewer cravings.
The keto diet can help you lose weight but is not recommended in comparison to more sustainable diets.
Starting the keto diet comes with a number of challenges — first, it’s very restrictive.
A notice: The ketogenic diet is a very low-carb, high-fat diet that forces the body into a metabolic state called ketosis, where fat is burned instead of carbs. The keto diet can result in weight loss that’s difficult to sustain long-term given the restrictive nature of the diet.
“To be successful on a ketogenic diet, you need a good foundation in nutritional knowledge and the ability to read labels,” says Emilie Vandenberg, a nutritionist at Ohio State University Wexner Medical Center.
Adds Vandenberg: “You need to know the macronutrient composition of most foods. It can also be difficult to eliminate or avoid certain foods.” Macronutrients are the nutrients found in food that your body needs in the greatest amounts to function properly. These include protein, fat and carbohydrates.
Still, this diet promises some potential benefits, including better blood sugar control for people with type 2 diabetes, weight loss, and fewer seizures in people with epilepsy. Below, experts explain some important things to consider before starting the keto diet. This includes how you will feel shortly after starting the diet and what the health risks are if you stick with the diet long-term.
1. There may be changes in digestion
The most common side effects of the keto diet include diarrhea, acid reflux, nausea, and constipation, Vandenberg says. Constipation is common because the keto diet prohibits whole grains and starchy vegetables, and eats fruit in very small portions and is low in carbohydrates. All of these foods are good sources of dietary fiber, which makes it easier to pass stool. Paula Doebrich, MPH, a registered dietitian in nutrition practice, says the keto diet typically includes the following components (although the ratios may vary slightly):
- Fat: 70 percent to 90 percent of total calories
- Protein: One gram per kilogram of body weight (e.g. 68 grams for a 68 kilogram person)
- Carbs: Calories left (usually between 100 and 200 kilocalories, or about 50 grams)
Gastrointestinal symptoms “can last as long as someone is on the diet,” says Vandenberg. “Others get used to the diet change and the gastrointestinal symptoms may go away.”
2. Flu-like symptoms could occur
Within the first week of starting the keto diet, some people experience a range of symptoms, also known as the “keto flu.” Symptoms are usually similar to the common flu and can include:
- brain fog
- muscle cramps
- difficulty sleeping
Fortunately, according to Doebrich, this is usually just a temporary side effect of severely reduced carb intake that should wear off after about a week. Vandenberg advises gradually reducing carbohydrate intake over a few weeks and staying hydrated to help reduce these symptoms.
3. You might feel more flabby than usual
According to experts, it’s normal to feel momentarily tired after starting the keto diet. That’s because your body is slowly adjusting to a different metabolic state that doesn’t rely on carbohydrates for fuel. “As your body adjusts to using fat for fuel instead of carbs, your energy levels can return to normal,” Doebrich says, adding that this fatigue typically lasts one to three weeks. However, Doebrich points out that people who…