The National Health Service will collapse unless people start to get a grip on their unhealthy lifestyles, the head of the cash-strapped service has warned.

Speaking at an event on 18 May where Prime Minister David Cameron put forward his plans for a seven-day NHS, Simon Stevens, its chief executive, said Britain was a society which "normalises obesity". And, he added, alcohol abuse cost the NHS £5bn (£7.8bn) a year.

Stevens, who has warned the NHS needs an extra £8bn a year by 2020 to ensure it can cope, said "concrete, sometimes controversial action" on lifestyles was needed.

He said: ‎"As a nation it's time to get our act together on prevention. Yes, life expectancy is its highest ever. But smoking still explains half the inequality in life expectancy between rich and poor - and two thirds of smokers get hooked as kids.

"Binge drinking costs at least £5bn a year - in A&E admissions, road accidents, extra policing.

"Junk food, sugary fizzy drinks and couch potato lifestyles are normalising obesity – and as parents, a third of us can't now spot when our own child is seriously overweight.

"So we've got a choice. Condemn our children to a rising tide of avoidable diabetes, cardiovascular disease, cancer? And burden taxpayers with an NHS bill far exceeding an extra £8 billion by 2020?

"Or take wide-ranging action - as families, as the health service, as government, as industry - using the full range of tools at our disposal. It's a no brainer – pull out all the stops on prevention, or face the music."