Possible keys to living longer

The post Can Exceptional Longevity be Predicted? that hit the Longevity Science blog recently has some interesting findings (based on a small sample, so take them with a grain of salt).

The authors state that "scientists currently disagree on whether a small or a large body size is conducive to exceptional longevity. Historical demographers are confident that small body size is associated with increased mortality, while biologists are firmly convinced that a small body size is preferable for longevity." So if you are of either body type you can take comfort:)

Additionally, "Numerous historical studies have found that body height in young adulthood is a good indicator of a past history of nutritional and infectious diseases. Infectious diseases (and diarrheal diseases in particular) that were highly prevalent in the past clearly led to growth retardation and a shorter body height, making shortness a marker of an unhealthy childhood and impaired health." That doesn't seem too surprising. The followup states "It could be expected that shorter people raised in a less healthy environment would have higher death rates at older ages as well. In his pioneering study published in 1984, Norwegian demographer Hans Waaler found a negative relationship between body height and mortality later in life. Waaler’s initial findings were reproduced later in many other studies, including a famous study of U.S. Union Army Civil War veterans. According to these studies, future centenarians should be taller than their peers." It seems that longevity is yet one more advantage for the tall.

But wait: "Our study confirmed that obesity at young adult age (being stout at 30 years) is detrimental to attaining exceptional longevity, while height is a far less important factor. The findings that a stout build predicts much lower survival rates to age 100 were consistent with existing knowledge that particularly high body mass indexes (BMIs) and obesity are associated with increased mortality."

The question that comes to mind then is what is the effect of a person being not stout until after age 30? In other words, if a person starts to put on a few pounds in the 35-45 age range, is there a significant negative effect on longevity?