Dr Xand van Tulleken investigates whether claims about negative effects of carbohydrates on health are true. The film looks at cutting-edge research into a possible link between carb consumption and infertility, and it investigates whether genetic changes are taking place when passing eating habits on to children. Xand and a team of volunteers attempt to guess how much sugar a selection of common foods each releases into the bloodstream. The film also sets out to examine whether it is possible to eat carbs in a way that is much healthier. Scientists have discovered that starchy carbs like pasta, rice and potatoes can be changed in a very simple way to make them healthier, and there is a surprise in store for Xand when he heads to the gym with his favourite carb-filled sports drink. The programme also teams up with a Merseyside GP to trial a healthy-eating plan which asks people to swap 'sugary' carbs for more fibre. The results after just two weeks come as a surprise.