The Academy of Medical Royal Colleges, which includes the RCGP, said previous efforts to stem the rising tide of obesity had been 'piecemeal and disappointingly ineffective'.
Its report, Measuring Up, said the problem of obesity in the western world had now hit 'unprecedented proportions'.
Doctors have put forward 10 recommendations following a six-month inquiry into the issue.
Proposals include a ban on new fast food outlets being located near to schools and colleges, and a 20% duty on sugary soft drinks to be piloted.
The academy also wants to add calorie information into the traffic-light system of food labelling, invest £100m on weight management services across the country, and prevent companies advertising foods high in fat, sugar and salt before 9pm.
Professor Terence Stephenson, a paediatrician and chair of the academy, said: 'As health professionals, we see it across all our disciplines – from the GP’s surgery to the operating table and everything in between. So it is no exaggeration to say that it is the biggest public health crisis facing the UK today. Yet too often, vested interests dub it too complex to tackle.
'It’s now time to stop making excuses and instead begin forging alliances, trying new innovations to see what works and acting quickly to tackle obesity head on - otherwise the majority of this country’s health budget could be consumed by an entirely avoidable condition.'
Over a quarter of adults and a third of nine year olds are overweight or obese. Obesity-related illness now costs the NHS £5.1bn a year.
A DH spokesman said: 'The threat posed by obesity in both adults and children represents one of today's most important public health challenges. This wide-ranging report from the Academy of Medical Royal Colleges recognises, as did our own recent Call to Action on Obesity, that there is no single answer to the obesity problem.
'It is up to everyone - government, industry, health professionals and voluntary groups, as well as individuals themselves - to work jointly to promote healthy eating and healthy lifestyles.'