A topic I revisit here and at the Longevity Meme with depressing frequency is the damage done to health and longevity through holding on to excess body fat. There's a lot of denial on this topic, but it's hardly rocket science: the weight of scientific evidence clearly shows that extra fat increases the risk of all sorts of age-related conditions that will cut years from your life. Not to mention the years in which you're made more miserable than you would have otherwise been due to suffering those conditions.
Not all of the mechanisms by which fat tissue hurts us are fully understood, but enhanced levels of chronic inflammation seems to be one of them. Correlation with lack of exercise is no doubt another, given the large difference regular exercise can make to your healthy longevity over the years. We already know that rising levels of chronic inflammation are important in shaping the deterioration of the aging body, and it looks like extra fat tissue creates that issue earlier and in greater force than would otherwise be the case.
I noticed a popular press article today on one of the recent studies that links fat to a shorter, less healthy life:
The studies used Body Mass Index (BMI), a measurement that divides a person's weight in kilograms by their height squared in meters to determine obesity. Researchers found that death rates were lowest in people who had a BMI of 23 to 24, on the high side of the normal range. Health officials generally define overweight people as those with a BMI from 25 to 29, and obese people as those with a BMI above 30.
Peto and colleagues found that people who were moderately fat, with a BMI from 30 to 35, lost about three years of life. People who were morbidly fat - those with a BMI above 40 - lost about 10 years off their expected lifespan, similar to the effect of lifelong smoking.
Moderately obese people were 50 percent more likely to die prematurely than normal-weight people ... obese people were also two thirds more likely to die of a heart attack or stroke, and up to four times more likely to die of diabetes, kidney or liver problems. They were one sixth more likely to die of cancer.
This is in the same ballpark as other studies and reviews I've seen in past years. If you want a better chance of living longer, don't get fat - it's pretty much common sense.