Researchers reviewed data from participants ages 31 to 80 in both generations. BMI was the main measure, which is used to determine whether a person is underweight, normal weight, overweight or obese.
Scientists controlled for a range of factors found to impact morality, including smoking, disease, education, marital status and gender. Then, they calculated how each BMI trajectory — six for the younger generation and seven for the other one — was linked to mortality rates.
It was found that people who began at a normal weight and changed to being overweight later on were the most likely to survive in both generations.
Despite the same basic results, some concerns arose with the pattern established by the younger cohort.
“The higher BMI trajectories in the younger generation tend to shift upward at earlier ages relative to their parents,” Zheng said.
“Even though the mortality risks associated with obesity trajectories have decreased across the generations, their contributions to population deaths increased from 5.4% in the original cohort to 6.4% in the offspring cohort,” Zheng noted, as the proportions of those with a higher BMI systematically increased in the younger generation.
“That’s because more people are in the obesity trajectories in the offspring cohort,” he added.