The Ketogenic Diet: What does the science say?

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[Photograph found in KetoLogic]. (n.d.). Retrieved December 11, 2018, from

By now, you may have heard numerous things about the ketogenic diet, including all sorts of anecdotal claims regarding its efficacy for addressing various health issues. “Keto” has become a major buzz word in the mainstream health sphere and continues to gain popularity. Some people swear by this diet, claiming that it is the magic bullet to things such as fat loss and mental health. Others advocate against it, under the premise that the high fat with low carbohydrate intake will cause problems like fatigue, obesity, and heart disease. So with so many opposing claims all over the media, confusion arises and we may feel unable to decipher who we should trust. Although the ketogenic diet seems controversial and is not quite understood yet, there has been some recent research done on the topic that can be useful when deciding whether or not such a diet is the right approach for you.

What is a ketogenic diet?

Lots of people do not quite understand the answer to this question, so I think it is important to address it. A ketogenic diet is not a paleolithic diet nor a carnivore diet. While a paleo and a carnivore diet are about what foods you eat, a ketogenic diet is centered on the macronutrient ratio of your caloric intake, regardless of which foods make up those macronutrients. This type of diet usually consists of about 70-75% fat, 5-10% carbohydrates, and 15-25% protein. If we based this on a 2,000 cal/day intake, this would consist of about 160 g of daily fat and about 30 g of daily carbohydrates. To many, the quantity of fat that this diet entails seems alarmingly high, and rightfully so, as we have been conditioned to believe that high fat consumption poses a risk to our health. But is this type of diet actually dangerous, or is it a completely safe way to manage numerous health problems, as some people seem to think? Does it help in the treatment of certain illnesses? Is it a useful tool for achieving weight loss? The literature takes us to various conclusions regarding these issues.


(n.d.). Retrieved December 11, 2018, from

The theory behind the function of the ketogenic diet is that by eating less carbohydrates, a person deprives themselves of glucose and glycogen stores, reduces insulin (a so-called “fat storing” hormone) surges, and begins to tap into his/her own body fat (or consumed fat) and produce ketones to use for energy (as opposed to glucose from carbohydrates). This idea began from experimentation with fasting on people with epilepsy. In the early 20th century, it was discovered that fasting would create a form of starvation that would encourage the body to release ketone bodies into the bloodstream to be used for fuel by the brain, and that seizures were reduced as a result. The biggest problem with this approach was that fasting was not sustainable (because people get hungry after a while). Through further exploration, it was then discovered that a very high fat, very low carbohydrate diet was able to mimic the effects of fasting without the burden of remaining hungry for extended periods of time. And so began the extensive research and experimentation on the ketogenic diet which has led us to where we are now, surrounded by claims that the diet is a “magic pill” for many. But what does the scientific evidence actually tell us about this diet?

Reported Benefits

Let’s start off by explaining some of the health benefits that can come from a ketogenic diet. Lots of studies have indicated that this type of diet can help with epileptic seizures, polycystic ovarian syndrome, autism, bipolar disorder, Alzheimer’s, Parkinson’s, type 2 diabetes, tumors, fat loss, and appetite suppression. This is a long list of potential health benefits, which makes this diet seem like the optimal one for so many different types of people.

Most of the research of how a ketogenic diet can treat certain illnesses has been done in regards to epileptic seizures. These studies show that a ketogenic diet can be helpful for some people. The diet has even been shown to have a long-term seizure-reducing effect on some patients even after they are off the diet. But this is not completely effective for everyone. The results vary from person to person. Some experience a partial seizure reduction, some become completely seizure free, and some do not experience any benefits at all and therefore decide to quit the diet because of undesired effects such as lethargy, digestive issues, and cognitive decline. Lots of the people that are responsive to a ketogenic diet are also responsive to medication, which means that those that are difficult to treat with medication tend to also be difficult to treat using a ketogenic approach. So this is a potential alternative form of controlling epileptic seizures, but the efficacy varies and the mechanism is not yet very well understood.

Polycystic ovarian syndrome (PCOS) is one of the most common hormonal disorders in women of reproductive age. It’s usually associated with insulin resistance, obesity, excess testosterone, and missed or irregular menstrual periods. There are studies that examine the effects of a ketogenic diet on overweight and obese women with PCOS. While there is an indication that the diet does improve symptoms of PCOS, these may be more of a result of weight loss and insulin management that result from the diet. This means that PCOS may potentially be managed just as effectively by reducing insulin resistance and losing fat mass without necessarily using a ketogenic approach. Also, while most women with PCOS are overweight and insulin resistant, not all women are. A smaller percentage of women with this condition are underweight and have low body fat percentages; in such cases, weight loss induced by a ketogenic diet may exacerbate the problem.

There have not been very many studies conducted that examine how this type of diet affects individuals with autism, but the few that are available indicate some improvement. Unfortunately, this diet is not effective for everyone. About 60% of the people who stick to the diet for an extended period of time see improvements. But this still indicates that it may be effective for some people looking to improve autistic-related behaviors.

Studies regarding how the ketogenic diet affects people with neuro-degenerative diseases such as Alzheimer’s and Parkinson’s indicate that it can be an effective way to reduce symptoms and improve memory and cognitive function, but the mechanisms are yet to be understood. Some believe that it may be due to elevated β-hydroxybutyrate levels, which is an effect of a ketogenic diet, but this is still unclear. Just like the illnesses previously mentioned, some individuals experience benefits from implementing this type of diet, while others do not, and there is still only a small amount of research regarding the issue. Further experimentation is necessary to make any strong evidence-based claims about how effective and how safe this diet is for those with neuro-degenerative illnesses.

There are also studies that suggest that a ketogenic diet can be an effective way to treat tumors. The theory is that cancer cells feed off of glucose, so by consuming a very low carbohydrate diet and relying on ketones for energy, a cancer patient can “starve” the tumor and prevent it from growing. Some cancer patients on a ketogenic diet have experienced a reduction in rate of tumor growth, others have reported a reduction in size, and there has been a report of one subject who became completely tumor free when fed a calorie-restricted ketogenic diet in conjunction with standard radiotherapy. General improvement of quality of life in cancer patients following a ketogenic diet have also been reported. Unfortunately, the amount of experimental research on this subject is extremely limited, and most of it has been conducted on animal subjects. Furthermore, there have been some human studies that have reported subjects experiencing an advancement in tumor growth after adopting a ketogenic diet, which may suggest that different types of tumors are affected differently by it.

One of the biggest reasons that people are interested in this diet is for the potential effects that it can have on type 2 diabetes, fat mass loss, and appetite suppression. It has been shown to be more effective for reducing hemoglobin A1c levels (a blood marker for diabetes) than moderate-carbohydrate low-fat calorie-restricted diets. Studies have also shown that overweight diabetic people have improved mood, less cravings, more fat loss, and a decreased need for diabetic medication on a ketogenic diet versus higher carbohydrate diets. Some of these studies have been conducted measuring net carb intake (total carbohydrates – fiber), while others have been done using total carbohydrate intake, but they both seem to have some sort of positive effect. Overall, a ketogenic diet seems to be an effective way to manage diabetes and obesity, but the long-term metabolic effects are still unclear.

Reported Adverse Effects

Now that we have explored the potential health benefits of a ketogenic diet, it’s important to mention some of the adverse effects that have been reported on participants of this experimental research. Some of these include gastrointestinal disturbances (including diarrhea, vomiting, nausea, and constipation), increased inflammation, thinning hair/hair loss, kidney stones, muscle cramps, fatigue, hypoglycemia, cognitive impairment, mood swings, nutrient deficiency, growth decline in children, decreased bone integrity, bruising, infections, pneumonia, cardiovascular decline, and menstrual irregularities. This is an extensive list of things that can go wrong when adhering to this diet which should be considered before adopting it. But perhaps these negative effects are experienced because most of the research is done on people with illnesses and health impairments, as opposed to general healthy individuals. Also, it is possible that some of these things could have been avoided by changing the quality of the diet and by implementing more frequent professional monitoring of subjects’ health markers. Another downside to the ketogenic diet is that plenty of the original participants of the above mentioned studies withdrew from the trials because of negative effects and/or because the diet was difficult to maintain, which brings into question the sustainability of it.

Overall, there is still a need for more scientific research regarding the long-term effects that ketogenic diets have on people with different illnesses as well as healthy individuals. Most of the benefits that we have heard about it are based on anecdotes rather than experimental studies, which leaves us with a lack of understanding. This does not mean that everyone should avoid this type of diet, but it does mean that anyone who intends to partake in it should be aware of the potential harms and should routinely monitor their health markers through a physician while on the diet. Personally, I believe that plenty of people looking to benefit their health using a ketogenic-style approach can achieve similar results by simply removing highly-processed carbohydrates and sugar from their diet. It is also important that these individuals focus on high-quality fats from animals and/or plants rather than consuming fried fats and vegetable oils. I do not think that limiting healthy whole-foods (such as VEGETABLES) for the sake of staying within a certain carbohydrate limit is necessary nor effective in improving the health of the general population, especially when considering the lack of evidence and possible adverse effects.

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