According to the Telegraph:

Smokers, heavy drinkers, the obese and the elderly should be barred from receiving some operations, according to doctors, with most saying the health service cannot afford to provide free care to everyone.
…
About one in 10 hospitals already deny some surgery to obese patients and smokers, with restrictions most common in hospitals battling debt.

Managers defend the policies because of the higher risk of complications on the operating table for unfit patients. But critics believe that patients are being denied care simply to save money.
…
Obesity costs the British taxpayer £7 billion a year. Overweight people are more likely to contract diabetes, cancer and heart disease, and to require replacement joints or stomach-stapling operations.

Meanwhile, £1.7 billion is spent treating diseases caused by smoking, such as lung cancer, bronchitis and emphysema, with a similar sum spent by the NHS on alcohol problems. Cases of cirrhosis have tripled over the past decade.
…
Among the survey of 870 family and hospital doctors, almost 60 per cent said the NHS could not provide full healthcare to everyone and that some individuals should pay for services.

But Michael Moore told us that health care is free in the UK. What is all this talk of "costs"?

Meanwhile, the NHS and nanny staters in the United States ignore the overall savings that smokers and the obese provide to health care systems… by dying young.

According to Dutch researchers:

Although effective obesity prevention leads to a decrease in costs of obesity-related diseases, this decrease is offset by cost increases due to diseases unrelated to obesity in life-years gained. Obesity prevention may be an important and cost-effective way of improving public health, but it is not a cure for ncreasing health expenditures.

The researchers used their model to estimate the number of surviving individuals and the occurrence of various diseases for three hypothetical groups of men and women, examining data from the age of 20 until the time when the model predicted that everyone had died. The “obese” group consisted of never-smoking people with a BMI of more than 30; the “healthy-living” group consisted of never-smoking people with a healthy weight; the “smoking” group consisted of lifetime smokers with a healthy weight. Data from the Netherlands on the costs of illness were fed into the model to calculate the yearly and lifetime health-care costs of all three groups. The model predicted that until the age of 56, yearly health costs were highest for obese people and lowest for healthy-living people. At older ages, the highest yearly costs were incurred by the smoking group. However, because of differences in life expectancy (life expectancy at age 20 was 5 years less for the obese group, and 8 years less for the smoking group, compared to the healthy-living group), total lifetime health spending was greatest for the ealthy-living people, lowest for the smokers, and intermediate for the obese pople.

Besides the fact that the fallacy of saving health care costs by eliminating smoking and obesity is intuitive, I believe there is another reason so many people believe that smokers and fat people should be denied health care. People don’t like smokers and fat people for moral and aesthetic reasons. Therefore, they think that it is good for “those people” to suffer.