Pofessor Greg Whyte: Fat is not an Olympic legacy issue, fitness is

The global pandemic of obesity that blights developed nations has driven a national obsession which has demonised fat and created a "fatist" society. For over two decades we have been subjected to a media vilification of those who dare to carry a few extra pounds and an incessant diatribe of diet propaganda purporting to possess the panacea for health.

On closer inspection, however, it would appear that size may not be the only – or indeed the most important – factor in determining the nation's health. The focus on diet linked to the volume and make-up of calories we consume has overshadowed the importance of the critical half of the energy balance equation: physical activity.

Health and physical activity are synonymous. As a species, the structure and function of our bodies are governed by our movement. Unfortunately evolution has dealt a potentially fatal blow not directly to our body and soul, but to our environment. Industrialisation, alongside the development of transport and technology, has resulted in an increasingly sedentary society.

Obesity is merely an outward sign of the true global pandemic: inactivity. Accordingly, it is our sedentary lifestyles we should look towards if we are to save our species.

Inactivity increases the risk of a range of chronic diseases, from diabetes to cancer. A recent study from the United States reported a higher rate of premature deaths associated with inactivity compared with diabetes and smoking combined. In contrast, other studies have demonstrated the greater importance of exercise over body size alone.

Indeed, it appears it is healthier to be "fit and fat" than it is to be "thin and unfit". Increasing one's physical activity through daily living and exercise has a more positive effect on health than weight loss through diet alone. Furthermore, physical activity is valuable in combating mental health issues such as depression.

All told, physical activity is the "magic bullet" for health as it targets physical and mental health and, combined with its social benefits, it has the power to truly enhance well-being.

Unfortunately, it is those least likely to engage in sociocultural change that appear to suffer the most at the hands of the grim reaper's slothful right-hand man: the young. Inactivity during the formative years of development has a profound effect on future health and that is why physical activity promotion for young people holds the key to the health of the nation, physical and economic.

The answer to this conundrum may be at hand if the government and the London Organising Committee for the Olympic Games (Locog) can deliver on the promise they made when winning the bid to host the Games. The focus of Locog on young people in the bid document was widely regarded as the key to its success. Underpinning the involvement of young people was the promise of an Olympic "legacy" focused upon increasing physical activity.

At first sight London 2012 seems to have provided the answer to all our prayers; however, the benefit comes in the delivery, not the promise. With less than five months to go there is little evidence of a lasting legacy to support the promise. Of greatest concern is the abject failure of those in power to take responsibility for delivering the promise – Locog and the government appear to be at odds as to who should be delivering legacy.

Hosting the Games is a once-in-a- lifetime opportunity in that we have a unique chance to provide the foundations of a cure for the epidemic of inactivity. Unless we act now, that opportunity may be lost.

The true value of the Games will be reflected by the legacy left behind. Unlike the "Wimbledon effect" which sees tennis courts across the land booked solidly for two weeks followed by 50 weeks of desolation, the Games must deliver long-term: reducing sedentarism and improving the nation's health cannot be delivered with a quick fix of Olympic hysteria.

It requires planning and long-term investment even in times of "austerity". Inactivity is the biggest health problem this nation faces – and the cure for it may only be in our reach until the Olympic flame goes out.

Professor Greg Whyte is a former Olympian & sports scientist