This post started as a question from one of my friends. When they found out about my interest in nutrition they asked me my opinion on the ketogenic diet. I am still in the process of learning and originally was more interested in separate ingredients rather than a certain “diet” so I had no answer for them at the time. I had heard of the ketogenic diet and knew that it had something to do with high amounts of fat but that was the extent of my knowledge. The question made me curious about this diet so I did some research to try and understand more about it and form my own opinion.
First of all, let me tell you what keto diet actually is. Glucose is known as the main source of energy for our bodies and is often referred to as the only source of energy for our brain cells as it can cross the blood-brain barrier while most things can’t. Turns out that our bodies are pretty clever and if they don’t receive enough glucose to power our brain they find another way to fuel it. In particular, they use fats to produce ketones that can get through to the brain and provide the needed energy. That’s exactly what ketogenic dieters aspire to do. In order to achieve this state, also known as ketosis, you have to minimise your carb intake (main source of glucose) and only consume as much protein as necessary for maintaining body structure. The rest of the diet consists of fats. There are many variations of keto diets but on average the split is 75% fat, 15% protein and 10% carbs. That means cutting out pretty much all grains (including bread, pasta, rice and cereal), potatoes, legumes, fruits and anything sweet. The main ingredients of a keto diet are meats, fish, cheeses, eggs, avocados, nuts, oils, butter and a low to moderate amount of green vegetables.
There are a few legitimate reasons why some people choose this particular diet for weight loss:
- Since the food eaten is mostly fats and proteins, it makes you feel fuller and more satiated.
- When you eat less carbohydrates, there is a decrease in insulin and ghrelin production, both of which promote appetite, so you don’t feel as hungry.
- Ketone bodies themselves have been shown to reduce hunger.
- Using fat and protein as fuel requires more energy that converting carbs to glucose so your body uses more calories to process them increasing calorie expenditure.
- It promotes fat loss rather than lean body mass loss, partly due to decreased insulin levels.
In 2014 review, authors have found that a period of low carbohydrate ketogenic diet may help to control hunger and may improve fat metabolism and therefore reduce body weight. A 2013 meta-analysis of 13 studies concluded that individuals assigned to a keto diet achieve a greater weight loss than those assigned to a low-fat diet.
All in all, it seems a pretty effective weight loss tool. Additionally, our body stores 3g of water for every 1g of glucose so when we stop eating carbs the body uses up all the glucose and gets rid of the excess water. That usually means that there is a significant weight loss in the beginning of the journey that can act as a good motivator.
Is ketogenic diet healthy? Here is where is gets complicated. People often see something that helps them lose weight as inherently healthy but that’s not always the case. Ketogenic diet has very broad rules – avoid carbs, eat fats. There are many different types of fats that can be beneficial or detrimental to your overall health in the long term. Keto friendly foods such as avocado, nuts, seeds and oily fish are full of healthy fats and it’s a great idea to include them in your diet. On the flip side, keto foods like bacon, steak, burgers, ham, sausages and vegetable oils are likely to harm your health in the long term and increase your mortality risk. When you cut out carbs from your diet you are cutting out a lot of added sugar in the form of soda, cookies, ice-cream, crisps, fries etc which is a great step towards better health. But at the same times you are cutting out a lot of fruit, vegetables and legumes that have consistently been shown to reduce risk for disease and provide benefits for your health.
Another issue is that we don’t know whether ketosis is healthy or dangerous as the mechanisms are not very well understood. It looks like it’s relatively harmless in the short term as there are many people on keto diets that aren’t experiencing any problems but we just don’t know what it does to our body long term. Some keto followers claim that it is a healthier alternative to our normal “glucose-eating” brain but until we have longitude studies following keto dieters for many years and looking at their health, disease and mortality, we will not know the answer.
A 2017 article looked at various studies on rodents and humans regarding keto diet effect on cardiovascular risk factors, such as cholesterol, blood pressure and insulin resistance. The results are pretty confusing as in rodent most of the risks went up, whereas in humans they went down. The authors speculate that it could be due to the fact that human participants were obese at the beginning on the study and that weight loss itself has contributed to the improvements rather than the type of the food they were eating.
A vast majority of nutrition experts and dietitians are pretty skeptical about keto diets and the impression I got is that it’s because, if we base our assessments on the scientific evidence we have to date, it shouldn’t be healthy. What we know with a high degree of certainty is that plant-based foods, fruit and vegetables and legumes contribute to better health outcomes, and keto diet turns this dogma upside down with its preference for animal products.
After doing some social media research I found that different people follow keto diet in different ways. Some see it as a green light to eat things that might not be “allowed” on a more traditional diets, i.e. aforementioned bacon, burgers etc. Others take a different approach by only consuming healthy fats and some even doing “vegan keto” cutting out animal products altogether, even though that makes the diet extremely restrictive and more difficult to sustain long term.
I believe that’s one of the reasons why scientific research on keto is so inconsistent. Others are that most studies are very short term and are on smaller populations. I couldn’t find out exactly what foods were used in human studies and how adherence to the diet was measured. If the researchers provided participants with a general guidance of “low carb, high fat”, it would inevitably lead to accessing a group of people that are on very different diets nutritionally.
A controlled study in healthy individuals looking at the physiological health regardless of body mass loss and calorie intake has not yet been done. Lucky for us, a team of researches are currently doing exactly this so we can expect some new data to be available in the coming months. Unfortunately, their study is pretty small and short term (20 individuals that will stay on a diet for 3 weeks), but it’s still interesting to see what the outcomes are going to be.
There is only one area where a ketogenic diet has been consistently shown to work – child epilepsy. The mechanism is not currently known but adhering to a high fat diet does help reduce the amount of fits in some children. It’s currently used as a treatment strategy alongside medication for this condition.
The question is, if keto diet can treat epilepsy, can it treat something else?
Some potential of a ketogenic diet has been shown in cancerous tumour reduction. Many tumours are not able to use ketones for fuel and are dependent on glucose for energy. A systematic review in 2017 has looked at 13 rodent studies on this topic, 9 of which have demonstrated that ketogenic diets significantly increase survival time and slow down tumour growth. But evidence is inconsistent and there are a few studies showing the opposite effect. It seems that the outcomes are largely dependent on the type of cancer and can vary dramatically. Human studies are rare and inconsistent at the moment so we are still awaiting larger and more controlled experiments before any recommendations can be made.
There has been some indication of positive effects of keto diets for individuals with type 2 diabetes but a 2015 review concluded that even though low carbohydrate diets are effective for weight loss and improvements in glycaemic control and heart disease risk, they are not superior to other dietary approaches. In other words, much of the positive effect of a ketogenic diet is due to weight loss rather than the diet itself.
There is very limited information on keto diet effect on neurological disorders, such as ADHD, autism, Alzheimer’s, anxiety and depression. It’s literally either anecdotal evidence or small single studies on mice and dogs. As you can imagine, it’s not easy to access depression in mice. At this point, there is just not enough evidence to suggest any possible association.
That doesn’t mean that ketogenic diet is necessarily a fad but before we can say one way or another, there need to be several large highly controlled studies that all show consistent results with regards to ketogenic dieting. Until then the official stance is that unless you are epileptic there is no good reason to follow a ketogenic diet and there is a chance that it might cause you more harm than good in the long run.
Ketogenic diet might help you lose weight slightly quicker than other popular diets in the short term but there is concern of whether this diet is beneficial for optimal health in the long term. Usually, following a ketogenic diet is simply not necessary. If you do decide to choose to use this diet as a weight loss tool, it’s best to do it for a short period of time and under your doctor’s supervision.