So far we’ve been learning how to stabilise blood sugar by eating less and ‘slower’ carbs, which break down into glucose, the fuel for our cells. But glucose isn’t the only fuel, nor the preferred fuel of brain cells (neurons). If given the choice they’d rather run off ketones.

Ketones are high energy molecules generated by the liver from fat. If you fast, your body will turn to breaking down body fat and it will make ketones. It’s an alternative fuel and there’s more and more evidence that ‘switching’ every now and again and going ‘ketogenic’ has all sorts of health advantages – especially for neuro-degenerative disorders. In fact, this kind of diet has been used successfully for a hundred years to reduce fits in those with epilepsy.

• Watch this film on how the brain makes energy
• Read this Report: How Your Brain and Body Make Energy

This is a big topic, and now that you’ve learnt how to eat GL, one option is to experiment with going ketogenic for a week or two. Why? Well, it’s a great way to lose weight, reverse diabetes, restore brain function and hopefully switch on ‘autophagy’ – a cellular ‘clean up’ process that rebuilds your mitochondria which are the energy factories in cells. This is something you want to read about first, get prepared for and know how to make healthy keto-friendly recipes.

There are a few books that can help starting with The Hybrid Diet by Jerome Burne and Patrick Holford which explains both low GL (slow carb) and high fat (ketogenic) eating together with enough recipes to get started, and The Ketogenic Cookbook by Jimmy Moore and Marie Emmerich.

In a nutshell, you switch out that quarter plate of carbs for high fat foods. Your meals will be delicious and varied, and they will contain copious amounts of fat and protein from fish, meat (mostly white rather than red), eggs, raw nuts and seeds, cream, butter, cheese and full-fat milk, plenty of green leafy vegetables, such as cauliflower, cabbage, broccoli and Brussels sprouts, as well as natural plant oils from coconuts, avocados and olives. This will change the proportions of the three macro-nutrients you eat to:

• Fat must provide 65-80 per cent of your daily calories
• Protein providing 20-25 per cent
• Carbohydrates just 5-10 per cent

The basic principles are:

1. Eat three meals a day plus one snack.

2. Just like the ‘slow carb’ phase, fill half your your plate with vegetables (but avoid high carb veg such as potatoes, parsnips, broad beans and sweet potatoes), and one quarter with protein – the amount of meat or fish that would fit into the palm of your hand.

3. Keep ‘simple’ carbs to the bare minimum i.e have no more than 15 GL of carbs a day. See the photo below of what constitutes 5 GLs. For example, a small serving of berries, 2 oatcakes and a small serving of bulgur would be all your carbs for the day. Half an avocado with taramasalata is 2.5 GLs, as is two eggs with salmon or three slices of bacon, or a salmon steak with a bag of spinach, sauteed with a tablespoon of coconut butter, butter or ghee. Snack on high fat nuts and seeds – walnuts, pecans, peanuts and pumpkin seeds are good – avoid cashews.

Our recommendation is to spend one week a month in the high fat/ketogenic phase, but if you like it, do it for two weeks. Some people lose more weight on slow carbs, others on high fat but the interesting advantage is what it does to your brain, energy and concentration. It’s variation, not moderation, that is the key to health – so this is a good way to explore your ‘hybrid’ nature.