After some time, however, your body becomes accustomed to that change and the diarrhoea stops. It’s then that the subsequent shortage of fibres from your low-carb diet sets in, and the wrath of constipation begins. If your 2010 Honda Accord runs on unleaded petrol, your brain runs on glucose, which is a simple sugar that is formed by breaking the carbohydrates you eat. Now, there’s plenty of glucose stored in your body, but when that thing runs out, your brain switches its fuel to, guess what? Ketones are, as I mentioned in the beginning, formed by the breakdown of fats in the liver — and we all know just how much we have that stored within our body.