Before we dive further into weight loss, a note: Weight loss isn't for everybody, and neither is following a specific, restrictive eating plan. If your goal is to lose weight, that's fine, but your health matters more than a number on a scale (and if you have a history of disordered eating, you should discuss any plans to change your diet with a doctor first). In addition, successful long-term weight loss is the product of many factors: Your physical activity, how much sleep you get, stress management, and other factors like medical issues and hormones all play an important role. What you eat is just one part of the weight loss puzzle.
Diarrhea can also be due to a lack of fiber in the diet, says Kizer, which can happen when someone cuts way back on carbs (like whole-grain bread and pasta) and doesn’t supplement with other fiber-rich foods, like vegetables. It can also be caused by an intolerance to dairy or artificial sweeteners—things you might be eating more of since switching to a high-fat, low-carb lifestyle.
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.