As a general rule, and after decades of experience in the industry, I believe that diets are not sustainable. Nothing beats a well-rounded balanced diet, which should be adjusted to your body type.

However, there has been a lot of interest in the 'Keto' diet and why it may have a place in the fitness industry. But why?

All diets are designed to put your body into a temporary state of ketosis. But most people have no clue what "ketosis" really means. 

So, what is ketosis? 

•    Ketosis is a metabolic state where your body does not have enough glucose to burn as energy.

•    Ketosis is the build-up of acids called "ketones" in your body. This build-up is triggered by a lack of glucose to burn.

•    Ketosis is a state when your body burns stored fat as energy (instead of glucose).

It’s vital to understand how ketosis works because ketosis (AKA: burning FAT as fuel) is the reason every single weight loss diet works or doesn’t work.  

Here’s how you can better understand ketosis and the most effective way to get your body to use stored fat as fuel:

Eating an 80% fat diet for 3 days gets your body into ketosis without reducing calorie intake. Once in ketosis the body burns body fat for fuel instead of using carbohydrates and proteins and the body goes into starvation mode. When you continue to do your exercises in ketosis, your body shouldn't drop weight and strength, but should just drop your body fat.

It is claimed that an average adult can drop their body fat by 0.75% average a week in the first 8 weeks. This is the main reason why people go onto this diet, but there is another reason. Fat as a macro-nutrient has a value of 9 kcal, whereas carbohydrates and proteins both have a value of 4 kcal. Once the body is properly conditioned to burn fat for fuel (this usually takes 8 weeks) the body should be able to store more fuel using this type of energy and therefore should be able to perform for up to 4 hours without having to take in food.

You would usually run out of fuel after about 2.5 hours of exercise when using carbohydrates and proteins as main fuel sources. This is the reason that a lot of endurance athletes and ultra-runners use this diet so they can perform better for longer.

Testing the theory

Feeling skeptical? Yes, me too, so for the first time in my life I started a diet, The Keto Diet. 

With the upcoming O.C.R Championships, to help improve my performance, I decided to give it a go in the short term. I worked out I can shave about 5 minutes of my finish time if I can reduce body fat by 4%, keep my weight by increasing muscle and also not having to reduce the pace to allow food intake.

Really - all this for 5 minutes? Yes - this year the World Championships are held in England and will be even more competitive, alongside the fact that I am another year older within my age category.

Keto or Ke-not-to?

I started the diet and in the first week, I lost 1kg of fat (0.8% body fat) whilst maintaining my weight and energy levels. However – I felt that 4 weeks of this diet would leave me gaunter than I would like. In a nutshell - the diet works if you strictly follow it, but it restricts you to eat very little carbohydrates – this even includes fruit and vegetable content too. As a professional, it seemed to me (and to most people) that this is not healthy to sustain long-term. Scientists also claim that if you exercise in an anabolic state (for most people above 85% of heart rate max) the body isn't capable to metabolise (i.e. breakdown) the fat for fuel properly. Carbohydrates seem still to be king at doing exercise at high heart rate and exercising below anabolic state (below 85%) allows metabolising fat for fuel better. 

This is just my personal experience of the keto diet, and any radical changes in diet should be discussed with your GP.