The Ketogenic Diet - What, How, Pros and Cons

by James Eacott

The ketogenic diet continues to gather momentum in the athletic community. Adopters claim the diet improves fat burning, weight loss and endurance performance. What’s more, it also appears to boost mental focus and key health markers

What is the ketogenic diet?

Ketones are molecules which can provide a fuel source for the body when its main reserves are depleted. It’s the word ketones that give the ketogenic diet its name.

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The aim of the ketogenic diet is to create an environment in your body where glucose is no longer available to provide energy. Once glucose stores are depleted, you switch to utilising alternative fuel sources found in keto bodies. These primarily derive from fatty acids in your diet and body fat.

To deplete glucose stores, you must drastically reduce carbohydrate intake.

Essentially, the ketogenic diet is a high fat, moderate protein, low carb diet which has you consuming no more than 50 grams of carbs per day.

The ketogenic diet – what can I eat?

When it comes to macronutrient composition, you’re looking at a split around:

Fat. No guidelines on quantity. Eat as much as you need to feel satisfied
Protein. ~1.5g protein per kg bodyweight
Carbs. 50g per day max but 20g is the sweet spot (one banana has ~25g carbs).

the ketogenic diet - eggs are your friend

Eggs. High in fat and moderate in protein – perfect for the keto diet

This means your diet will consist of:

Meat. Keto is not a high protein diet, so you don’t need much to hit your goal
Seafood. The fattier the better
Eggs. Any way you want them
Veggies. Those grown above ground - cabbage, avocado, broccoli and cauliflower
Dairy. The higher fat content the better. No milk due to sugar content
Nuts. Depending on the type as some (cashews for example) are higher in carbs
Berries. Strawberries, raspberries and blackberries

On the face of it, this looks like a fairly health list. Nothing processed or high in sugar. The focus is on nutritious, natural food and we like that. Maybe we could get on board.

So, what can’t eat on the ketogenic diet.

The ketogenic diet – what can’t I eat?

Carbs, basically. That includes:

Sugar. Soft drinks, sweets, cereals, cakes, biscuits and chocolate
Whole grains. Oats, brown rice and wheat
Fruit. Bananas, oranges, mango, pineapple, apples
Starches. Potatoes, bread, pasta and rice
Pulses. Beans and legumes

the ketogenic diet - carbs are off the table

But this tasty bowl is right off the cards!

The ketogenic diet – the pros

Despite controversy around low-carb diets, there's research highlighting many positives of a ketogenic diet:

Weight loss. Due to the high fat intake, satiety increases. Furthermore, studies show that when calories from carbs and replaced with calories from fat and protein, fewer calories overall are consumed. However, despite effective short-term weight loss, it’s worth noting that long-term studies have shown no difference in weight loss between those who followed a low fat and a low carb diet.
Boosts ‘good’ cholesterol. Higher HDL levels means decreased risk of heart disease
Energy and mental performance. Blood sugar and insulin levels are reduced drastically with the knock-on effect of reducing – even reversing – Type-2 diabetes.
Increased endurance. After a period of adaptation – and that’s the key – a low carb diet can be beneficial for endurance. Once adapted to utilising ketones for fuel, an athlete can perform at a low intensity for longer than their carb-dependant counterparts who need to neck a sugary gel every 20-minutes.

Ketogenic diet – the cons

The list of pros is rather convincing, so what about the downsides of the keto diet?

the ketogenic diet - sprint performance will decrease Thinking of sprinting on the ketogenic diet? Think again!

Decreased power and speed. Your ability to undertake intense training is compromised because your preferred fuel for these activities – carbs – aren't available
Bad for heart health. Many of the foods on the 'can’t eat' list are beneficial for heart health whereas many on the 'can eat' list – particularly saturated fat – are detrimental
Lack of fruit and veg. This is a real sticking point. Fructose, in its natural form (aka whole fruit and veggies) is a great slow-burn fuel source because the fibre within naturally regulates absorption. Fructose only gets bad when it's processed into a syrup (such as high fructose corn syrup).
Starting is hard. A period of adaptation is needed and, as carb stores deplete, it can be unpleasant. Expect to feel lethargic for a week or two
You don’t get enough sugar. Of course, that’s the point. But your body – brain included – needs sugar to function and some keto report decreased focus
Lack of long-term research. Due to its recent appearance, no lengthy studies on the impacts of a very low carb diet can say whether it’s good or bad for health.

Ultimate Daily Greens - a perfect accompaniment to the Keto Diet

Ketogenic diet – conclusion

Our position tends to be that any kind of 'diet' is not going to deliver long-term performance and health gains. The historic meaning of diet suggests a temporary change to your eating habits...which tend to be unsustainable. Plus, the lack of long-term impacts of the ketogenic diet are yet to be uncovered.

There is some good evidence that, in the short term at least, a ketogenic diet can improve fat burning and improve endurance. But the exclusion of a huge range of fruits and vegetables is just not something we can get along with.

If you were to try the ketogenic diet, we'd recommend doing so during the off-season when the implications of any 'cons' are lower. When you make the switch, incorporate our Ultimate Daily Greens – they’ll cover any nutrient bases you might be deficient in.