'Unpleasant side effects can occur with the Atkins diet. To                    start with, burning fat results in the production of                    substances called ketones as your body enters a state called                    ketosis. This can result in bad breath, tiredness, weakness,                    dizziness, insomnia and nausea. Constipation may also occur as                    a consequence of avoiding typically high-fibre foods such as                    fruit, veg, beans, wholewheat pasta, brown rice, wholegrain                    breakfast cereals and jacket potatoes.' - taken from a diet reveiew website.