Balance of payments. Health benefits from doing any sport, including pot holing, mountaineering and horse riding, outweigh the damage done by the low nunbers of those that fall off. Every Sunday the hospitals see a run of footballers with broken ankles and cruciate injuries, along with people who have fallen off bikes, but these people are all fitter and generally healthier than the thousands who sit and watch TV instead.
Junk food and peanuts, well, we all have to eat. Junk food attracts VAT if served hot, and a bit of VAT funds the hospital cardiac wing. In addition, you have to weigh up the cost of pensions against health care. As an example, a friend of mine was always obese and was never going to claim a pension for 20 years. In the event he didn't get to 60 and was still working and paying tax when he died. That's a positive for the exchequer.