The Programme, week 5: Nutritionist's comments on Sarah

Matt Lovell: The first week on no wheat or bovine dairy is over and, except for one piece of toast and Marmite, all went according to plan. As well as continuing on avoidance of toxins and allergens, the plan now is to get strict on additives and preservatives and stick to food as close to nature prepared it as possible.

This will involve not eating anything out of a box (as a general rule) as well as steering clear of convenience and fast foods. Obvious sources of these are McDonalds and Chinese, less obvious are some tinned foods and ready-to-cook foods.

These changes are not as difficult as it might appear: changing from Ready Brek to organic porridge oats with organic milk; from normal baked beans to Whole Earth baked beans (sweetened with apple juice); low fat crackers to oat cakes; fast food to a healthy home-made cooked breakfast (with all the right ingredients of course).

During this time it's also crucial to focus hard on exercise – it complements the more stringent dietary regime and can also help occupy some of the evening time, excess of which may lead people off the straight and narrow.