Viagas believes there are three immutable tenets of any good detox, the first being 'eat simple': as a rule of thumb, the closer the food is to its natural state, the better. Biomechanically, we're still functioning like cavemen, so eat according to the seasons, one food group at a time. Secondly, drink lots (two litres of water a day). And thirdly, junk the toxins (no alcohol, soft drinks or cigarettes; swap coffee and tea for fennel and nettle teas).