The study that I remember them quoting/citing is very, very poor quality. It looked at the weight of individuals at death, and concluded that people who die when older tend to be slightly fatter.  See the problem already? You're a smart fucker. Most people tend to become sedentary in the last few months of life, confined to their bed or home as health problems add up. Of course they're not going to be super fit as they struggle for breath and struggle to the bathroom to squeeze out a single drop of urine.  Of course, that led to fat fuckers saying that being overweight causes you to live longer, rather than the truth, which is older deaths gain some weight at the end.