As the sun comes out (or not!) the doctors are back doing science research on our behalf. While we prepare to bare our bodies on the beach, Dr Saleyha Ahsan and the University of Oxford test whether it is really possible to bust belly fat, and skin surgeon Gabriel Weston takes a special camera on the streets to see how protective sun cream actually is. Dr Chris van Tulleken tests how cheap a pair of sunglasses we can buy and still be assured protection from damaging UV light. And as the warmer weather tempts more of us to do some exercise, GP Zoe Williams makes a guest appearance to test what it's really doing for our health, whilst Michael Mosley investigates some surprising ways to get the benefits of exercise without doing any at all.