New research suggests a higher metabolic rate may be tied to early natural mortality. This finding could indicate that higher than normal energy levels are associated with early aging in humans.

In animals, higher energy levels are linked to a shorter lifespan. However, the association between a higher than normal basal metabolic rate and accelerated aging in humans has been obscure.

In the study, investigators examined whether energy expenditure, measured in a metabolic chamber over 24 hours and during rest, predicts natural mortality.

“We found that a higher endogenous metabolic rate, that is, how much energy the body uses for normal body functions, is a risk factor for earlier mortality,” said Reiner Jumpertz, M.D., lead author of the study.

“This increased metabolic rate may lead to earlier organ damage (in effect accelerated aging) possibly by accumulation of toxic substances produced with the increase in energy turnover.”

“It is important to note that these data do not apply to exercise-related energy expenditure,” added Jumpertz. “This activity (exercise) clearly has beneficial effects on human health.”

In the study, researchers evaluated 652 non-diabetic, healthy Pima Indian volunteers.

The overall 24-hr energy expenditure was measured in 508 individuals, while resting metabolic rate (RMR) was measured in 384 individuals.

Total energy expenditure was tracked between 1985 and 2006 with a mean follow-up time of 11.1 years, while RMR was evaluated between 1982 and 2006 with a mean follow-up time of 15.4 years.

During the study period, 27 study participants died of natural causes.

Researchers found that as energy expenditure increased, there was also an increase in risk for natural mortality.

“The results of this study may help us understand some of the underlying mechanisms of human aging and indicate why reductions in metabolic rate, for instance via low calorie diets, appear to be beneficial for human health,” said Jumpertz.

Source: Endocrine Society