Out-of-shape people are more likely to change their lifestyle and improve their health if offered a cash incentive, research has found.
A study looked at how effective incentives were for 30,000 people who were set challenges such as giving up smoking.
Newcastle University researchers looked at 16 previous studies and found sums as small as £3 could make people up to 50% more likely to make changes than with standard interventions.
Financial penalties for failure also worked, and the research team found large incentives were not necessarily more effective than smaller ones.
But it was not clear if the positive impact would continue in the long-term after the rewards had stopped and the researchers said more work would be needed to establish whether the policy could save the NHS money.
Newcastle University research associate Dr Emma Giles said: "This was an interesting finding and we were surprised at just how strong the effect was.
"People who took part in these reward or penalty schemes were much more likely to adopt healthy behaviours, and if they continued they would have more chance of remaining healthy for longer.
"Many studies used vouchers for supermarkets or similar things rather than actual cash. This might be a more acceptable way of implementing this."
Dr Jean Adams, a senior lecturer in public health, said: "We were surprised how few studies we found which had looked at the impact financial incentives can have.
"At this stage we don't know the right level that incentives should be at, so it is not clear if this sort of scheme would save the NHS and country money.
"We try all kinds of techniques to try to help people to quit smoking or otherwise live healthy lives, so why not try this? It is about nudging people to healthier behaviours.
"There is a chance this could save the taxpayer money in the long run."
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