The low-carb, high-fat approach to the keto diet limits the types of foods you can have, and entire food groups are eliminated entirely. Beans, legumes, and whole grains are out, as are many fruits and vegetables. Many of these foods carry vitamins, minerals, and other nutrients you can’t get from any other source, and without them, you may start to experience nutritional deficiencies.
“Keto is not a great long-term diet, as it is not a balanced diet,” says Nancy Rahnama, MD, an internal medicine and bariatric specialist in Los Angeles. “A diet that is devoid of fruit and vegetables will result in long-term micronutrient deficiencies that can have other consequences,” she says. “The keto diet can be used for short-term fat loss, as long as it is under medical supervision.”
Constipation and bowel changes
Eliminating most fruits and vegetables can have other consequences, too. Without fiber-rich foods, you may begin to experience bowel changes, including difficulty having a bowel movement and eventually constipation. Luiza Petre, MD, a board-certified cardiologist and weight management specialist in New York City, suggests focusing on eating more low-carb, fiber-rich foods to help beat this bowel issue. “Try fibrous vegetables, such as broccoli, asparagus, and cabbage, consume more fat like MCT oil, coconut oil, or ghee, and, as always, drink plenty of water,” she says.
Loss of electrolytes
As ketosis begins, your body will start dumping glycogen, which is an energy source of carbohydrate stored in the muscles and liver. This will increase how often you urinate and can lead to an inevitable loss of electrolytes, Dr. Rahnama says. Electrolytes are essential to cardiac function and normal heart beating. “The loss of electrolytes, such as sodium, magnesium, and potassium will put the dieter at risk of a cardiac arrhythmia,” Dr. Rahnama adds.
Look for natural sources of electrolytes or take an over-the-counter supplement. “Avocados, leafy greens, asparagus, and cruciferous veggies are great for providing important electrolytes, says Josh Axe, a doctor of chiropractic, certified doctor of natural medicine and clinical nutritionist in Nashville, TN. Ax also suggests a magnesium supplement to help you sleep and avoid cramps or constipation.