In its 2016 report “Healthy Eating Guidelines & Weight Loss Advice,” the Public Health Collaboration, a U.K. nonprofit, evaluated evidence on low-carbohydrate, high-fat diets. (The Keto diet falls under the LCHF umbrella.) Among 53 randomized clinical trials comparing LCHF diets to calorie-counting, low-fat diets, a majority of studies showed greater weight loss for the Keto-type diets, along with more beneficial health outcomes. The collaboration recommends weight-loss guidelines that include a low-carbohydrate, high-fat diet of real (rather than processed) foods as an acceptable, effective and safe approach.
But beyond that, experts aren't convinced that the keto diet has any other scientifically-proven health benefits. In fact, it may have some distinct downsides. If you follow the keto diet incorrectly, for example (like by eating lots of saturated fats, versus healthy unsaturated fats), you're at risk of raising your cholesterol levels. “The best strategy to keep your heart healthy is to get as much fat as possible from unsaturated sources such as olive, avocado and canola oils, nuts, seeds, avocados, and olives," says Ansel.
A systematic review in 2018 looked at 16 studies on the ketogenic diet in adults. It concluded that the treatment was becoming more popular for that group of patients, that the efficacy in adults was similar to children, the side effects relatively mild. However, many patients gave up with the diet, for various reasons, and the quality of evidence inferior to studies on children. Health issues include high levels of low-density lipoprotein, high total cholesterol, and weight loss.
-Cardiovascular Disease: High blood sugar has been shown to increase the risk for cardiovascular events, cardiovascular disease, and cardiovascular mortality—while lower glucose levels result in lower cardiovascular risk. Coronary artery disease risk has been shown to be twice as high in patients with impaired glucose tolerance, compared with patients with more normal glucose tolerance. The risk for stroke increases as fasting glucose levels rise above 83 mg/dL. In fact, every 18 mg/dL increase beyond 83 results in a 27 percent greater risk of dying from stroke. Incidentally, glucose can “stick” to cholesterol particles and render these particles extremely dangerous from a heart health standpoint, which is why it’s all the more important to control blood sugar levels if you’re eating a “high-fat diet.”
A short-lived increase in seizure frequency may occur during illness or if ketone levels fluctuate. The diet may be modified if seizure frequency remains high, or the child is losing weight. Loss of seizure-control may come from unexpected sources. Even "sugar-free" food can contain carbohydrates such as maltodextrin, sorbitol, starch, and fructose. The sorbitol content of suntan lotion and other skincare products may be high enough for some to be absorbed through the skin and thus negate ketosis.