For 30 years, the researchers kept track of volunteers who died and noted the causes of death. They sought to answer a simple question. The researchers found that until age 75, a higher body mass index was associated with a greater risk of premature death from all causes, including heart disease. Relative risk is a statistical method that compares a particular risk factor to other causes of death. The researchers found that the relative risk associated with obesity declined with age in people between 30 and 74.
Younger people have fewer disorders, so the relative risk of obesity is higher.
It declines steadily with age until about 74 years. Probably not, Thun says. Absolute risk, the actual number of deaths linked to obesity, is probably a more telling figure. The absolute risk associated with obesity goes up after age 30. Simply put, carrying too much weight becomes more hazardous as a person ages.