Smoothies and juices have an important role to play both during treatment and when recovering, as they offer an easy solution to maximise vitamin and mineral intake. However, it is important to avoid large portions of fruit-based smoothies as they can be extremely calorific and have a high sugar content – it is, after all, quite unnatural for us to eat 5-6 portions of fruit in one sitting. Although, the sugars contained within fruit are ‘natural’, when blended the fibrous outer walls of the plant cells are destroyed meaning the fructose is absorbed quickly from the gut and the whole fruit has moved from having a relatively low glycaemic index (GI) to becoming a high-GI smoothie. This will cause a peak in your blood sugar levels that could leave you feeling sluggish in a couple of hours.