A big increase in obesity threatens to cause health problems for millions of people across the world.
Tiredness and obesity can be linked
In this week's Scrubbing Up, obesity expert Professor Tony Leeds warns that our weight problems could also put the lives of other people at risk.
Britain is gripped by a much-publicised epidemic of obesity - one in four of us is clinically obese.
Many obese people face an increased risk of illnesses such as heart disease, diabetes and cancer. On average, their lives will be shortened by nine years.
But some might be unwittingly putting the lives of others at risk too.
These additional fatalities are occurring not in Britain's cardiac units, but on the country's roads, due to people falling asleep at the wheel of cars and lorries.
But why is this - and how many of us are unwittingly potential killers?
It is because Britain has yet to wake up to the dangers of obstructive sleep apnoea (OSA).
OSA may be more common than is realised, especially in people with type 2 diabetes, where one in four might be affected.
It causes snoring, interrupted by pauses in breathing, and choking and gasping during sleep. This makes sleep disturbed and restless, and can leave people tired, irritable, forgetful and depressed. It also increases the risk that they will fall asleep at work - or while driving.
OSA can be caused by structural abnormalities of the upper airway but obesity is a big risk factor.
Extra fat next to the airway can increase pressure on the muscles which support the airway, raising the risk that it will narrow and become obstructed.
The lifestyle of many lorry drivers means that many are significantly overweight. They lead a sedentary lifestyle, keep unsocial hours and might have unhealthy diets
A recent British Medical Journal study showed that losing weight by following a very low calorie diet led to significant improvements in symptoms in just seven weeks for 26 out of 30 obese men with moderate or severe OSA. A longer-term US study produced similar findings.
But the risks of living with the condition were graphically illustrated by another study, which calculated that people with severe sleep apnoea were between six and 15 times more likely to be involved in a road traffic accident.
Lorry drivers seem to be particularly at risk. The typical lifestyle means many are significantly overweight - they lead a sedentary lifestyle, keep unsocial hours and might have unhealthy diets.
One study found only 11% had a "healthy" body mass index - and half were above the obesity threshold.
Britain's leading sleep experts believe that nearly one in six lorry drivers could have sleep apnoea - that's nearly 80,000.
Perhaps we should call for a campaign to alert all drivers to the importance of adequate sleep
But difficulties when driving may be under-reported - perhaps for fear of losing their licence and livelihood.
In a period of just four months, at least four cases came before UK courts of drivers of large goods vehicles accused of causing death by dangerous driving.
All four drivers were suffering from sleep apnoea - diagnosed only after these terrible accidents.
In one incident it was revealed that a lorry driver involved in a fatal crash had seen his doctor just five months before, complaining of tiredness - but sleep apnoea was not diagnosed.
BODY MASS INDEX
Calculated by dividing weight in kilograms by height in metres squared
Normal: 18.5 - 24.9
Overweight: 25 - 29.9
Obese: Above 30
At the inquest, the coroner called for a toughening of the licensing regimen for commercial drivers, including regular medical screening.
He also called for fast-track medical assessment of those involved in road traffic collisions - but stressed that a diagnosis of sleep apnoea was unlikely to force them off the roads.
Survey data and random inquiry suggest that falling asleep (even momentarily) while driving may be more common than we realise. Our lifestyles, TV and computer use nibble away at the hours of sleeping.
Perhaps we should call for a campaign to alert all drivers to the importance of adequate sleep, to the effect that being obese can have on sleep quality, and to the need for an immediate visit to the GP if sleep apnoea is suspected.