Primary care should use these opportunities to motivate patients to take an interest in their weight and lifestyle, according to Hertfordshire GP Dr David Haslam, chairman of the National Obesity Forum.

But GPs must not become 'obsessed' with minor weight loss when seeking achievable gains to BP and cholesterol can do a great deal for overall health, he said.

Speaking at a Westminster Food and Nutrition Forum event on obesity in London on Tuesday, Dr Haslam said: 'I firmly believe that best practice can take place in one minute at the end of the consultation. It doesn't take more than a minute just to engage, as long as you then promise to follow-up what [risk factors] you find.'

Dr Haslam, also a bariatric physician at Luton and Dunsable Hospital NHS Foundation Trust in Bedfordshire, suggested GPs should use this time to get patients on the scales and to take their BP.

But the approach demands care, he warned. 'You can either engage or alienate,' he said.

'That one minute is the most important one minute in the whole obesity management programme. Get it right and you find you can do some good. If you get it wrong, that's it, you'll never see them again.'

He said this approach can improve risk factors for cardiovascular disease such as BP, cholesterol and blood sugar levels.

Dr Haslam said this was perhaps more important than weight loss itself. 'I think the reason [tackling obesity] is so unpopular is because we're too obsessed with a tiny number of kilograms lost.

'We should judge ourselves, and be judged, not just on those couple of kilograms... but on the effect it has on overall health.’