This can be tough for folks who need a "cheat" day, but it can also take a mental toll on the dieter. In a usual diet plan when you go off of it for a day or two, you just get right back in the saddle and start again. With keto it's more than that: You need to start from scratch to get yourself back into ketosis, which can take a few days or weeks. This can really make you feel bad about yourself and take a psychological toll on your well-being and self-worth. (Related: Why You Should Give Up Restrictive Dieting Once and for All)
In the first week, many people report headaches, mental fogginess, dizziness, and aggravation. Most of the time, this is the result of your electrolytes being flushed out, as ketosis has a diuretic effect. Make sure you drink plenty of water and keep your sodium intake up.6One of the fathers of keto, Dr. Phinney, shows that electrolyte levels (especially sodium) can become unbalanced with low carb intake.
Take a multivitamin. “Because you are removing grains, the majority of fruit, some vegetables, and a significant amount of dairy from your menu, a multivitamin is good insurance against any micronutrient deficiencies,” says Jadin. Depending on what your individual overall diet looks like, Jadin says you might also need to add a calcium, vitamin D, and potassium supplement.
There are three instances where there’s research to back up a ketogenic diet, including to help control type 2 diabetes, as part of epilepsy treatment, or for weight loss, says Mattinson. “In terms of diabetes, there is some promising research showing that the ketogenic diet may improve glycemic control. It may cause a reduction in A1C — a key test for diabetes that measures a person’s average blood sugar control over two to three months — something that may help you reduce medication use,” she says.