Hu and colleagues analyzed health data from nearly 120,000 study participants, including women in the Nurses' Health Study between 1976 and 2012, and men in the Health Professionals Follow-Up Study between 1986 and 2012.

Participants were asked to recall their weight from early adulthood, age 18 for women and 21 for men, and to report their weight at age 55.

Women gained an average of 12.6 kg over early to middle adulthood, and men about 9.7 kg.

Compared to those who kept their weight stable, those who gained a moderate amount of weight had an increased risk of major chronic diseases and premature death, and were less likely to score well on a "healthy aging" assessment of physical and cognitive health.

In a meta-analysis of study participants from the two cohorts, each five-kg weight gain was associated with a 30 percent increased risk of type 2 diabetes, 14 percent increased risk of hypertension, eight percent increased risk of cardiovascular disease, six percent increased risk of obesity-related cancer, five percent increased risk of dying prematurely, and 17 percent decreased odds of achieving healthy aging.

"These findings may help counsel patients regarding the risks of weight gain," the researchers wrote.