There are recent studies showing that being overweight is not the primary factor.

The primary factor is fitness.

People who are overweight but fit (due to regular moderate exercise) die at lower rates than unfit people.

"Men and women who were fit, as judged by a treadmill test, but were overweight or obese had a lower mortality risk than those of normal weight but low fitness levels, the study in the Journal of the American Medical Association showed."

And don't even get me started about people like me who are fit, toned, and over the "optimal" weight for my height. For tall people, the optimal weight is calculated with endomorphs. If you are not an endomorph, it's basically impossible to have any muscle and meet the desired weight targets.

This is about control over our behavior because they can. Just like traffic lights and other kinds of data mining.