The removal of many grains and fruits with such a large emphasis on fats can bring about its own set of side effects. “If not done properly — with most of your carbohydrates coming from fiber-rich vegetables — you may not be getting enough fiber, which can lead to constipation,” says Chris Mohr, PhD, RD, a sports dietitian based in Louisville, Kentucky, and co-owner of MohrResults.com. (5)
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.