While smokers and the overweight are often criticised for the financial impact of their unhealthy lifestyles, an obese person's medical bills actually average 10 per cent less overall than those of a person of normal weight.
Smokers require even less treatment, say the researchers.
The reason is that the healthy tend to live longer and so, while they might not have to battle lung cancer, heart disease or diabetes in their fifties, they may need long-term care for illnesses of old age such as Alzheimer's.
As a result, any "savings" made by them being healthy when young are more than offset by their being ill in old age.
Based on healthcare costs in Holland, where the study was conducted, a person of normal weight can expect their medical bills from the age of 20 to total £210,000 over the course of their lifetime, while an obese person's costs will be £187,000. Smokers, whose life expectancy is the shortest of the three, cost the least, at £165,000, the researchers from the National Institute for Public Health and Environment calculated.