• Emilina Lomas

What’s the science behind keto? Does it work?

You have most likely heard of the ketogenic diet. According to Google Trends, it was the most searched diet of last year. But you may be wondering whether it’s the best diet for you, so keep reading to hear about the good, the bad and the ugly, when it comes to keto.


Similar to the Atkins diet popularized in the 1960s, the keto diet cuts out carbohydrates. The diet recommends that your total daily calories are made up of 70-80% fat, 20-15% protein and 10-5% carbohydrates. This typically equates to around 20-40 grams of carbohydrates for the average person, which is the same as one apple.


Unlike the Atkins diet that recommends high quantities of protein, the keto diet limits protein intake as it has been shown to impact the ability to reach ketosis. The whole focus here is fat.


‘So what even is it?’ ‘How does it work?’ I can hear you asking… Let me explain.





When you eat carbohydrates, your body converts them into glucose to burn for fuel and insulin is produced to process the glucose in your bloodstream preparing it to be used or stored as glycogen.


However when no carbohydrates are present, a few metabolic changes occur. Firstly, your blood sugar levels drop making you feel tired and lethargic. This is the first step in adapting to a ketogenic diet, or becoming what is commonly referred to as ‘fat-adapted’. This step is inevitable and is often referred to as the ‘keto flu’.


Secondly, once you push through, the liver starts using the fatty acids from fats and converts them into ketone bodies to burn for fuel, as a substitute for the glycogen. This metabolic adaptation is known as ketosis.


There are three types of ketones produced when the body enters ketosis: acetoacetate, beta-hydroxybutyric acid and acetone, that all have specific functions in providing your body with energy in the absence of glucose.

What are the benefits of following a ketogenic diet?


The benefits of the Keto diet are extensive. Initially the diet was recommended to prevent epilepsy and to treat behavioural issues in children with autism, but is now used by scientists, athletes and ordinary people around the world.


Some of the cited benefits include: sustainable and substantial fat loss, improved mood, better quality of sleep, mental clarity and sustained energy levels. Let’s explore some of these.


One study tested the ketogenic diet for 24 weeks on obese patients, and found significant body weight reductions, an increase in good (HDL) cholesterol, and decreases in bad (LDL) cholesterol, triglycerides and blood glucose.


A study conducted on rats found that the ketogenic diet acted as a mood stabilizer, with the rats showing fewer signs of depression and ‘behavioral despair’. This can be supported with anecdotal evidence in humans, so is pretty well supported.


As the Keto diet is high in fat and protein, you will feel satiated for longer. When fat enters the small intestine it slows digestion, increases fullness and as a result decreases appetite. A 2005 study in The American Journal of Clinical Nutrition showed that a high fat and high protein diet increased satiety and decreased appetite and calorie intake, when compared to a diet lower in fat and protein.


The ketogenic has been shown in studies to have strong neuroprotective effects, which is why it is a potent treatment for epileptics and individuals with neurological conditions like ADHD or autism. This is, in part, due to its anti-inflammatory properties, and in part because ketones are a neuroprotective antioxidant that prevent harmful reactive oxygen species from damaging brain cells. Ketones are also responsible for increasing mitochondrial efficiency, by increasing the production of genes involved in energy metabolism.


As the diet removes carbohydrates, keto eaters will experience stable blood sugar levels, meaning less energy highs and lows. This is great news if you have diabetes, in fact some case studies have used the keto diet as a treatment to reverse diabetes with a high success rate.


Having a stable blood sugar helps you to maintain energy levels throughout the day, rather than experiencing the after lunch slump. It has also been linked to reduced sugar cravings, mood improvement and better sleep.






What are the negatives of following a ketogenic diet?


It may seem like a small price to pay considering the above benefits, but one commonly reported complaint on keto is that your breath doesn’t smell too great. One of the three ketone bodies produced in ketosis is acetone, which is excreted through your breath. In case you’re wondering, yes it’s the same acetone that is found in your nail polish remover and smells pretty similar too.


A large scale study that examined low vs. high carbohydrate diets, found that those with the lowest intake of carbs had a 32% higher risk of all-cause mortality. These diets also came with an increased risk of coronary heart disease (51%) and cancer (35%), compared to those eating higher carbohydrate diets.


This is perhaps because the ketogenic diet does not put a particularly strong emphasis on fruit and vegetable intake, because ultimately they are carbs. However, research shows you need to be consuming an abundance of fruit and vegetables to enjoy optimal health.


Some nutritionists argue that individuals on a ketogenic diet are often low in magnesium, calcium and potassium because these nutrients are typically found more so in carb rich foods like bananas.


Healthy complex carbohydrates provide the body with much needed fiber, which is integral to gut health, so cutting these out of your diet isn’t a great idea when it comes to having a happy and healthy digestive system.


Recent research has also suggested that a low carb diet long term decreases the amount of short-chain fatty acids, good bacteria and antioxidants produced in your gut: chemical compounds that are necessary to fight free radical damage and disease. This is due to the diet being largely devoid of fiber.

Gut health is an indicator of your risk of disease and if it’s not well populated with good bacteria, you’re going to start facing some problems - like bloating, constipation and even colon cancer.


One of the major complaints on keto is that it is notoriously hard to stick to long term. The excitement of starting a new diet engages the best of us, which if you’re lucky leads to weight loss and a euphoric high. But for most, this phase passes, you lose interest and the weight starts piling back on.


Keto has a fairly low adherence rate compared to other more flexible diets, with the average person only lasting 1-3 months according to this research. This is likely due to the difficulty of sticking to the diet in social situations. Low carb alcohol only, no Saturday night pizza, no more of your favorite Starbucks order. To stay in ketosis, you can’t have slip ups.


Ultimately, the ketogenic diet is an anti-inflammatory diet that helps individuals lose weight. It has a range of powerful benefits that have been well researched. It can be a great tool for individuals with a lot of weight to lose, type 2 diabetic or struggling with a neurological or autoimmune condition.


But with every pro, there’s always a con. I think the main con for keto is that it can, unless followed attentively, be quite nutrient deficient and devoid of fiber. This has health implications in itself, but no long term studies have been conducted on this just yet.


So if you’re going to go keto, make sure you eat all the low carb fruit and veggies you can, and listen to how your body is responding.



What are the different types of ketogenic diets?



Standard Ketogenic Diet


As the name suggests, this is the standard version of the ketogenic diet. It involves eating less than 20 grams of carbohydrates per day, which equates to one small piece of fruit, for reference. This is the most common strain of ketogenic diets.


Cyclic Ketogenic Diet


Unsurprisingly, due to the vast benefits of being in a state of ketosis, many athletes are following a ketogenic diet. Athletes burn more fuel on a daily basis compared to most people, so the need for easily converted energy is more necessary. The Cyclic Ketogenic diet involves the athlete consuming higher quantities of carbohydrates for a couple of days to fully reload glycogen stores before going back into ketosis.


Restricted Ketogenic Diet


As you may be aware, keto and fasting go hand in hand. Intermittent fasting is often practiced by those doing the ketogenic diet to further increase the rate at which fat is burnt, amongst other more holistic reasons such as clarity of mind. The Restricted ketogenic diet involves more calorie restriction, less than 12 grams of carbohydrates are allowed each day. The diet is begins with fasting for three days. This is used as a treatment approach for cancer patients to decrease inflammation.


Targeted Ketogenic Diet


This type of ketogenic diet involves eating directly before or after workouts in order to maximize exercise performance. This is typically done by people who exercise at a high intensity frequently. This is similar to the Cyclic Keto diet but without the long carb loads because the intensity and volume of the exercise is not as much. The carbs are eaten 30 minutes to an hour before exercise to fuel glycogen stores and energy levels without interrupting ketosis.


High Protein Ketogenic Diet


This is similar to the standard type of ketogenic diet, but it involves eating higher portions of protein. The standard ketogenic diet involves consuming 25% of the daily calorie intake from protein and 70% from fats, but the high protein diet shifts to 60% fats and 35% protein. Being in a state of ketosis requires small quantities of protein so as to not disrupt the breakdown of fatty acids. But increasing the protein content slightly can improve muscle repair for those who engage in weight lifting and high volume training.


That's the 411 on keto, the good, the bad, the ketones. Like all diets, seek medical advice if you have any serious or chronic conditions that may affect your ability to adjust to a restrictive diet.


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