Childhood obesity increases the risk of developing multiple sclerosis, research shows.
Experts say that one in ten cases of the condition are linked to people carrying excess weight as a child or teenager.
Multiple sclerosis (MS) affects the brain and spinal cord, causing problems with balance and movement, as well as potential disability.
It is a lifelong condition that is usually diagnosed in people in their twenties and thirties.
Previous studies have found that more than half of MS risk is down to environmental factors.
The new study, by Queen Mary University of London and the University of Oxford, aimed to estimate how many cases were a result of smoking and obesity.
It found that obesity accounts for around ten per cent of the risk of developing MS, but this proportion could increase if childhood obesity levels continues to rise.
The study, published in the International Journal of Epidemiology, said that childhood obesity is projected to contribute up to 14 per cent of overall risk of MS by 2035.
It found that approximately 10 per cent of the population risk of MS could be attributed to smoking, but that this will decrease as smoking rates decline.
In contrast, obesity levels are increasing in the UK.
Around one in ten children are obese when they start primary school, but this doubles to one in five by the time they leave aged 11.
One in three adults in the UK are obese – meaning they have a Body Mass Index over 30 – and Britain’s spiralling obesity levels is placing growing pressure on the NHS.
Corresponding author Dr Ruth Dobson from Queen Mary University of London said: ‘Our findings highlight the potential to reduce the incidence of MS worldwide with targeted public health strategies. It is not only cancer and heart disease that are influenced by smoking and obesity – shifting the focus to diseases with onset in early adulthood, such as MS, may resonate more with younger people whose lifestyle choices will have an impact on their risk of future illness.’