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Ketogenic Diet Review: A Look at Current Research and the Impact on Health

According to U.S. News and World Report, the ketogenic diet held the number 1 spot in the top ten most googled diets in 2018. It’s not surprising as this diet has many followers who testify that it has helped them lose weight, improve their health, and in some cases, changed their life.

If you’re a regular Twitter user as I am (@Nutritionpro_1), there are ongoing debates amongst the most zealous keto advocates who strike down dissenters who may disagree with their diet philosophy. In spite of many dietitians and doctors who don’t advise following the keto way of eating, those in the “keto camp” continue to tout the benefits.

The ketogenic diet has been around for a few years now, so we have more evidence as to whether or not it does what the people who advocate success stories claim it does. Before we get into it, I would like to start by saying I support the choice to eat in style a person wishes. It is my job to guide them to help improve health. I don’t criticize those who come to me for advice, but I do have constructive opinions.

First, let’s establish what the ketogenic diet is. The standard keto diet is a very low-carb, moderate-protein, and high in fat. It typically contains 75% fat, 20% protein, and only 5% carbs. What other dietitians and I have found is that this is unsustainable long term for the average person. Additionally, because the diet has such a high-fat level, which includes saturated fat, it concerns health professionals like myself what the impact on heart health will be. The USDA's guidelines recommend that Americans consume less than 10 percent of their calories from saturated fats and replace the remaining fats with healthy monounsaturated and polyunsaturated fatty acids. On a 2000 calorie diet, that’s no more than 200 calories from saturated fat, a much lower amount than what you would be eating by adopting the keto percentages of fat.

When someone decides to adhere to the keto diet principle of a very low carbohydrate pattern, it is quite a shock to the body and experiences of nausea, vomiting, dizziness, sleepiness, and sluggishness are reported. If you’re a regular exerciser or are an athlete, taking the carbohydrate level of your diet down this low may not be the best choice. Carbohydrates, especially whole grains and fruit, supply the necessary energy and fiber your body needs to maintain energy levels. Not to mention the impact that the prebiotic fiber has on good gut health. As we learn more about the importance of maintaining a healthy gut microbiome for immunity, mental health, avoidance of digestive issues and disease prevention like cancer, I can’t stress enough that including carbohydrates in your menu is essential.


In our first piece of research, a meta-analysis of 13 studies which lasted longer than one year was performed. Scientists discovered that when the keto diet was followed, it amounted to less than 1 kilogram of weight loss compared to a high carbohydrate, low-fat diet pattern. Although this amount was meaningful statistically, in clinical practice, it wasn’t remarkable. The difference wasn't enough to conclusively state that the keto diet pattern made a difference.

The next study was a meta-analysis of 32 controlled feeding studies. The findings indicated that there was more significant fat loss and higher energy expenditure compared to ketogenic diets. Again, we can’t conclusively state that the ketogenic diet was better for weight or fat loss.

Whether or not someone loses weight and keeps it off has more to do with maintaining a calorie deficit and supports sustainable diet patterns. Usually, when someone decides to go on a specific diet such as keto, they’re also making significant changes to their lifestyle. Eating more vegetables, exercise, strength training, getting to bed at a reasonable time are factors that play into whether someone changes the number on the scale. Also, healthier choices at the grocery store, forgoing high sugar foods for vegetables and lean meat can significantly reduce calorie consumption, resulting in weight loss.


Due to the increase in obesity rates in both children and adults, interest in controlling type 2 diabetes has increased as we study the role of food, carbohydrates, and metabolism. There are approximately 27 million people in the United States, with type 2 diabetes. About 86 million people have prediabetes, which is when a person’s blood glucose is too high to be considered normal yet not high enough to be diagnosed as having diabetes.

Type 2 diabetes is a carbohydrate intolerance due to insulin resistance. Insulin is the hormone your body produces to facilitate the energy from food entering into your cells to be converted into energy for your body to use. Type 2 diabetes is exacerbated by obesity. It is a well-known fact that weight loss and improved dietary intake can improve symptoms and help control blood sugar. The question arises as to whether or not the ketogenic diet improves diabetes explicitly. In a meta-analysis (a study which looks at several studies on the subject and draws a conclusion based on the findings) of several long term research studies, the keto diet was compared to low-fat diets for weight management. There were no differences in blood sugar control between the two diets in study participants who had type 2 diabetes.

In my practice, which isn’t a scientific study but anecdotal, I have counseled clients on weight management and lifestyle improvement eating patterns. What I have experienced is that a person does not have to eliminate carbohydrates or severely restrict them to control blood sugar and type 2 diabetes. Portion control, better choices, and increased activity have positive results when implemented long term. The best outcomes happen when there is regular accountability and input from a Registered Dietitian. It may seem that I’m advocating for my profession, and I am. However, the results are apparent. Seek help from someone who knows the science of nutrition and diabetes.


There is some possible evidence that adhering to a ketogenic diet may improve serum lipids (fat) and increase high-density lipoprotein (HDL) cholesterol (the good kind of cholesterol). Additionally, low-density lipoprotein cholesterol (the wrong kind) may increase even though one may experience weight loss. Also, although a person may boost HDL levels, it doesn’t always translate into improved cardiovascular health.

One concerning finding with keto diets is that it is deficient in most vitamins and minerals and may be lacking in trace minerals. Selenium specifically may be insufficient and may result in cardiomyopathy. Supplementation is necessary when eliminating foods and food groups in this diet.

As a dietitian, the most concerning aspect of the ketogenic diet is the lack of fiber. Increased vegetable consumption is excellent and essential for a healthy diet. However, eliminating whole grains, fruit, legumes, and unrefined carbohydrates that promote health and provide crucial nutrients is not recommended. The positive impact that these foods have on the gut microbiome, cardiovascular disease reduction, colon cancer rate reduction cannot be overstated. Given the emerging research on these factors and how these foods play a significant role, eliminating them could be one of the worst choices a person can make for their health even though he or she experiences weight loss.

Additional known risks to long term ketogenic diet adherence include potential kidney stone formation, bad breath, sluggishness and fatigue, severe constipation, and muscle cramping. Since this diet is relatively new, we won’t know just how severe some of these complications may be for years to come. As more studies continue to emerge, and we have concrete evidence of the harm, my recommendation is to avoid the keto diet.

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