These types of back-and-forth weight fluctuations can contribute to disordered eating, Kizer says, or can worsen an already unhealthy relationship with food. “I think this diet appeals to people who have issues with portion control and with binge eating,” she says. "And in many cases, what they really need is a lifestyle coach or a professional counselor to help them get to the bottom of those issues."
Many have lost weight on the keto diet—but that is no surprise. If you're cutting out processed foods and limiting your carbs and protein, it's really tough to eat fat on its own. Think olive oil or butter—how much can you really take in? Those on ketosis do experience a decreased appetite due to higher amounts of ketones in the blood, which can also enable weight loss. But that doesn't mean you're doing it healthfully.
The ketogenic diet is not a benign, holistic or natural treatment for epilepsy; as with any serious medical therapy, there may be complications.[27] These are generally less severe and less frequent than with anticonvulsant medication or surgery.[27] Common but easily treatable short-term side effects include constipation, low-grade acidosis and hypoglycaemia if there is an initial fast. Raised levels of lipids in the blood affect up to 60% of children[37] and cholesterol levels may increase by around 30%.[27] This can be treated by changes to the fat content of the diet, such as from saturated fats towards polyunsaturated fats, and, if persistent, by lowering the ketogenic ratio.[37] Supplements are necessary to counter the dietary deficiency of many micronutrients.[3]
As far as keto's track record with longer term weight loss, a systematic review and meta-analysis that looked at 13 randomized trials that lasted at least a year showed that people who followed the ketogenic diet recommendations lost, on average, 2 more pounds compared to those who followed lowfat ones. But some experts say that weight loss from a keto diet probably isn't from any specifics about the diet itself. If the ketogenic diet aids weight loss, says Brian St. Pierre, R.D., director of performance nutrition at Precision Nutrition, it’s because it might enable some people to maintain a caloric deficit.
The ketogenic diet for weight loss is based on the idea that driving the body into ketosis will maximize fat loss. Ketosis is a normal metabolic process that occurs when the body does not have enough glucose stores for energy. When these stores are depleted, the body resorts to burning stored fat for energy instead of carbs.  This process produces acids called ketones, which build up in the body and can be used for energy. (2)
One downside to a ketogenic diet for weight loss is the difficulty maintaining it. “Studies show that weight loss results from being on a low-carb diet for more than 12 months tend to be the same as being on a normal, healthy diet,” says Mattinson. While you may be eating more satiating fats (like peanut butter, regular butter, or avocado), you’re also way more limited in what’s allowed on the diet, which can make everyday situations, like eating dinner with family or going out with friends, far more difficult. Because people often find it tough to sustain, it’s easy to rely on it as a short-term diet rather than a long-term lifestyle.