Ketogenic diets have an established history, with doctors recommending them to patients with diabetes and epilepsy. However in recent years they have become increasingly popular amongst body-conscious celebrities looking to enhance their health and boost fat loss. Kourtney and Kim Kardashian; actresses Halle Berry and Gwyneth Paltrow; and athletes like Lebron James swear by them. But is the evidence there or are they just another diet fad that seems to have gained momentum?
WHAT IS THE KETO DIET?
The Keto Diet claims that by banishing most carbohydrates (typically eating < 20-50g a day) and consuming 70% of your calorie intake from fats, you can teach your body to become a 'fat-burning machine' without feeling hungry.
HOW DOES IT WORK?
The theory behind the Keto Diet is based upon basic energy metabolic science.
How does increasing fats help you to lose fat?
If you consume more energy supply (calories) than you expend (through bodily functions, exercising, movement, brain activity etc.), then the body will store it as fat in unwelcome places. All energy provided by food (fats, carbohydrates, protein – the 3 macronutrients) is converted to ATP (adenosine triphosphate), which provides the cells with energy to produce movement. According to the Keto Diet, ketones are the 4th macronutrient. Ketone bodies (acetoacetate, acetone and 3-hydroxybutyrate) are produced in the liver by the process of ketogenesis, and are taken up by the vital organs, including the heart, brain and muscle, where via the citric acid (TCA) cycle they are converted into ATP for energy. When large amounts of fats are rapidly metabolized, ketone production increases, thus increasing energy and boosting metabolism.
The effect of reducing carbohydrates
The brain relies on glucose for energy; it can’t survive without it. Therefore, when carbohydrates are limited in your diet, the body produces ketones largely as a protective measure to ensure the brain’s survival in a low glucose environment.
Think: Have you ever been on a low carbohydrate diet and experienced symptoms of memory loss or a foggy brain? Chances are it was caused by lack of ketone production. With that in mind, when following a low carbohydrate diet, you’ll still want your brain to function properly and therefore getting into full ketosis via a full ketogenic diet is preferable to following a low carbohydrate approach where stimulating ketosis is not a priority. Low carbohydrate diets also affect insulin hormone storage. Insulin activates key enzymes in pathways, which store energy derived from carbohydrates. In the absence of dietary carbohydrates, insulin levels decrease, and this can lead to a reduction in lipogenesis and fat storage.
DOES IT WORK?
The ‘experts’ behind the diet suggest that ketogenisis can create a ‘metabolic advantage’, enabling you to burn an extra 4-600 calories daily. They clearly don’t understand energy metabolism. Moreover, the claims are largely un-evidence-based, similar to those used to sell other fad diets to those in search of ‘the best’ diet to help them lose body fat.
While it is true that you will burn a greater amount of fat relative to other fuel sources, you will be burning more fat because your intake is high, and your body prefers to use the fuel source that is most available. In that way, you almost become a ‘fat-burning machine’, however this simply means that your turnover is high. I.e. your fat intake and storage is ramped up, as is fat-burning for fuel. BUT that does NOT mean you will lose more stored body fat, merely that fat is the fuel source your body is prioritising. You could just as easily become a glucose-burning machine, but that does not sound as attractive when selling a diet, does it?
Nonetheless, whether you are a 'fat-burner' or a 'glucose-burner' is irrelevant when it comes to fat loss. We are discussing fuel sources, not stored body fat. What matters is: energy (calories) in versus energy out (activity). To lose body fat, your fuel intake needs to be less than your usage – you almost need to run your engine close to empty to lose the fat. How you achieve that makes little difference. There is no scientific evidence that ketosis eradicates stored body fat faster than any other approach and no valid evidence to suggest that you will burn 400-600 more calories daily by doing it. That is just pure nonsense.
‘The Keto Diet craze: the reason why people are putting butter in their coffee, chugging down keto drinks, and in some cases fasting for entire days.’
HOWEVER… DESPITE THAT THE KETO DIET DOES HAVE BENEFITS
Although there is no hard evidence to suggest that a ketogenic is better than any other when calorie intake is the same, it does have some benefits that may inadvertently effect fat loss, the largest being appetite suppression. Followers of the diet report experiencing a loss of appetite, which could alter energy balance, thereby allowing them to consume fewer calories than they are burning and creating the energy deficit required for fat loss.
If you struggle to maintain regular eating habits, often skip meals or have a busy schedule and don’t have time to eat, the Keto Diet could prevent you from feeling hungry whilst dieting – great because you won’t snack. In that aspect, it is better than a regular low carbohydrate diet as entering full ketosis helps to maintain good cognitive function. Hugely important for feelings of wellbeing, awareness, productivity at work and in the gym and more. It’s also a good option for people who enjoy eating higher fat foods, as they will still be able to eat bacon, cheese, butter etc. Remember: the best diet is the one that allows you to lose unwanted body fat and keep it off. It needs to be sustainable for you and your lifestyle.
The Keto Diet is not a magical quick-fix. The initial weight loss comes largely from stored water and muscle glycogen, not the fat you’d like. You’ll experience large fluctuations in weight for sometime and, interestingly, the true fat loss you experience over a given time will be the same as they would be with a moderate fibrous carbohydrate approach, as will the cognitive benefits.
You also need a lot of willpower. Followers fully understand how easy it is succumb to carbohydrate cravings. BAD NEWS! In that moment of weakness, they instantly get kicked out of ketosis and catapulted into several days of binging on carbohydrate heavy foods. Crave something as simple as a piece of fruit? Think twice before trying a ketogenic approach.
That said, for many people, maintaining a keto lifestyle isn’t a problem. Once it becomes habitual, they quite enjoy it and it can be sustainable. That’s the key thing. When entering a diet, think to yourself: can I maintain it in the long-term? Not just for a quick-fix weight loss, but as a lifestyle choice to keep me healthy, fit and energized, with the body results I want to see.