The Harvard School of Public Health demurs: http://www.hsph.harvard.edu/obesity-prevention-source/obesit...

And the argument that the longer lifespans of healthy people means they will consume more healthcare dollars sounds quite specious on the face of it. After all, healthy people do not have chronic conditions whereas the obese & smokers can spend 20-40 years being treated for hypertension, diabetes, heart failure, arthritis, emphysema, COPD, etc. How could people living, on average, an extra four to seven years without such chronic care possibly wind up costing more? As it turns out, the study you reference was not based on data from actual patient outcomes but is a mathematical model: http://www.plosmedicine.org/article/info%3Adoi%2F10.1371%2Fj...

David Strip calls into question the validity of the model thusly:

"Much in line with the response by Mittendorf, the validity of the results lies very strongly on key assumptions that are not demonstrated. The analysis assumes that the cost of an incidence of the 22 key diseases is independent of the risk factors being tested. Likewise, remaining health care costs, which account for 85% of health-care spending in the Netherlands , are assumed to be uncorrelated to risk factors. Given that this latter class of spending dwarfs the former, the importance of demonstrating the lack of correlation is particularly important. The incidence of numerous co-morbidities with obesity argues, in fact, that one might reasonably expect to find that the annual health costs are higher in the obese and that the cost of treatment in the last months preceding death may be quite different from the non-obese.

Kim McPherson, emeritus professor of public health at Oxford, wrote in response to the van Baal study here: http://www.plosmedicine.org/article/info%3Adoi%2F10.1371%2Fj...

In a sense, Van Baal and colleagues' study is a useful antidote to current concerns. But let us be clear: it does not attenuate them. Obese people cost less because individuals die younger and hence with less chronic morbidity associated with old age. This is a useful thing to know, but how might it affect public health strategies for obesity? In particular, does it mean that concerns about increasing population obesity are misplaced, as least as far as health-service costs are concerned?

Sadly not. Examine an obese population and a lean population of the same age and sex distribution, and the former will incur far greater health-care costs throughout the life course. Much more diabetes, and more cardiovascular disease and cancer will occur amongst the obese—even amongst the older obese [3]. Compare health-care costs now with those thirty years ago, and—holding everything but obesity constant—the current population costs much more to the health sector than it did then [4]. Moreover, quite apart from health-care costs, the other costs to society from obesity are also greater because of absences from work due to illness and employment difficulties; these costs amount to considerably more than health-care costs [5]. It is not clear that these extra costs are intrinsically related to health-care costs, but they are currently estimated to be around four times as great in obese than in lean people [5].