Wealth, in the most general sense, is a blade of many edges. Let us consider food, for example, which has moved over the centuries of growing wealth from being expensive and unreliably supplied to its present state of being cheap and exceedingly reliable in supply in all the stable regions of the world. That has been a passage of stages: from the bootstrapping of early longevity gains and better land use in the 1700s, all the way through to the stunning advances in productivity that resulted from applications of the first wave of modern biotechnology in the 60s and 70s. Unfortunately we humans are not well adapted for an environment of abundant and cheap food: by following our instincts and ingrained preferences we wind up fat and sedentary, a state that causes significant harm to health and longevity.

This is one of those temporary issues, a matter of a handful of decades. Medical biotechnology will catch up to the new demands of the population, and at some point humans will learn to alter themselves such that there are no longer any detrimental consequences to overeating, or being fat, or being sedentary. That isn't so far away: perhaps fifty years at the outside. In the meanwhile there is willpower or there is a shorter, less healthy life. Your choice.

The data on what exactly excess body fat will do to you - on average, statistically speaking - has been growing over the past years. Fat is metabolically active, an eager and pushy partner in the feedback loops and controlling systems of your metabolism. A lot of what it does is bad in the long term: spurring chronic inflammation, for example. Even comparatively early in life, putting on the pounds and keeping them on for years at a time has a sizable impact on your risk of later suffering all of the most common age-related conditions. Failing to exercise appears to be just as bad in a whole different set of ways.

In any case, here is recently published research from a long-term study that adds yet more data on the costs of fat tissue - and thus the costs of the lifestyle choices needed to gain and maintain that fat tissue:

While some past studies have shown that persons carrying a few extra pounds in their 70s live longer than their thinner counterparts, a new study that measured subjects' weight at multiple points over a longer period of time reveals the opposite. Research from Adventist Health Studies recently published in the Journal of the American Geriatrics Society showed that men over 75 with a body mass index (BMI) greater than 22.3 had a 3.7-year shorter life expectancy, and women over 75 with a BMI greater than 27.4 had a 2.1-year shorter life expectancy. Generally, a BMI between 18.5 and 24.9 is considered normal weight, and a BMI of 25 to 29.9 is considered overweight. A BMI of 30 or more is considered obese.

Previous work in this area by others found a protective association for a high body weight among the elderly. Pramil N. Singh, DrPH, lead author of the paper and an associate professor in the School of Public Health at Loma Linda University, says the data from many past studies is problematic because only a single baseline measure of weight was taken, which does not account for weight changes or how weight changes affect life expectancy. Additionally, most past studies had mortality surveillance of fewer than 19 years, which analyses have shown to be an inadequate amount of time to study risks associated with weight.

"We had a unique opportunity to do 29 years of follow-up with a cohort that was also followed for mortality outcomes," Dr. Singh said. "Across this long period of time, we had multiple measures of body weight, which provided a more accurate assessment."