Obesity is not a cost that can be calculated
Obesity is a body size, there are healthy and unhealthy fat people just like there are healthy and unhealthy thin people. The current state of oppression, stigma and shame around obesity means that any calculation of the cost of obesity is impossible to separate from the cost of that oppression, stigma and shame.
Obesity is correlated to a number of diseases so it is considered a “risk factor” although the term is used loosely since there is no proof of causality of risk, it’s as if they found out that short people get a certain disease more often but they have no idea why so they say that shortness is a “risk factor”. At any rate, a family history of heart disease is also considered a risk factor. The calculations that are commonly used to show the “cost of obesity” are often based on the assumption that obese people will get every disease for which they have a risk factor, or that every disease they get is caused by their fat. This is exactly the same as if we calculated the cost of people with a family history of heart disease based on the assumption that they are all going to get heart disease, or that any heart disease they get is caused by their family history. It’s just poor research.
Besides which, an attempt to calculate the cost of a group of people based on how they look in order to make a decision to eradicate that population because they’ve been deemed to expensive is clearly dangerous and wrong.”