This figure by comparison, sounds grossly underestimated (no pun intended).
Being politically correct, any other lifestyle choice is credited with illnesses and death, not obesity, even though it may in fact be the major contributor to a shortened life.
The number of clinically obese could just have occurred because they adjusted the numbers, not because there was that dramatic an increase in actual fat people.
And the health cost increase due to obesity is a judgment call. Someone has to decide that the condition was actually caused by obesity.