Restricting calories could protect against aging, scientist says

A
capuchin monkey in Trujillo, Honduras.
US Air Force/Capt. David J.
Murphy

Instead of survival of the fittest, evolution might actually be
about survival of the laziest.

That’s according to a
new study published Tuesday in the journal The Royal Society.
Researchers from the University of Kansas studied fossils of
ancient mollusks and gastropods, and found that
organisms with higher metabolic rates were more likely to go
extinct.

Animals that required less energy to power their daily
lives and maintain their bodily functions were more likely
to win in the long run, the results showed.

While metabolism isn’t the only factor that determines
whether a species goes extinct, the researchers suggest that it’s
a very important component of long-term survival. 

That new finding adds to a growing body of evidence that
links lower metabolism with longevity. (
Naked
mole rats, for example, are the longest living
rodents thanks to a quirk in their metabolism.)

Rozalyn Anderson, an associate
professor at the University of Wisconsin’s School of Medicine
and Public Health, told Business Insider that her work in monkeys
also suggests metabolism is at the center of the aging
process. 

“I think it’s all about energy: energy use, energy storage and
the type of pathways that are being engaged to derive energy,”
she said.

Restricting calories in monkeys

Anderson’s most recent
research has been on the impacts of restricting caloric
intake in Rhesus monkeys.

In a study of 76 monkeys published in
the journal Science in 2009, Anderson and her colleagues
found that restricting how many calories the animals consumed by
25% over
a span of 20 years made them age differently, compared to a
group of control monkeys that ate however much they wanted.

The monkeys who ate less were 2.5 times less likely to have an
age-related disease like cancer or heart disease.

“The calorically restricted animals age differently,” Anderson
said. “They don’t age slower, they age differently, and the way
they age is associated with less disease risk. And that
difference is in terms of their metabolism.”

She added that restricting a body’s caloric intake — the fuel it
takes in — alters how the body produces and consumes energy,
making it more energetically efficient.

Anderson also noted that the monkeys that underwent caloric
restriction maintained their level of physical activity as they
aged, whereas the control animals’ physical activity levels
decreased. She explained at a
conference in 2014 that for calorically restricted animals,
there’s a lower metabolic cost associated with movement — more
“bang for your buck” when it comes to trading nutrients for
usable energy units.

When humans
restric their calories, researchers have seen similar
outcomes. A two-year-long, NIH-supported study published in

The Journals of Gerontology in 2015 found that
participants who restricted their calories by 12% on average saw
decreases in risk factors that contribute to age-related heart
disease and diabetes. The experiment did not significantly
alter their metabolism, though. 

Read more:

Animals that defy the rules of aging — like naked mole rats —
could help scientists unravel the secrets to longevity

Shutterstock

Connecting the dots between factors in the aging process

Anderson said that in her various studies of different
facets of aging, she’s most fascinated when her research uncovers
pathways that converge and overlap. This is happening more and
more in the field of aging, and it’s helping her piece together
why caloric restriction seems to alter parts of the aging
process. 

“I think it’s all completely connected, and these are just
different ways of looking at the same phenomenon, which is the
things that change with age that makes older people more
vulnerable to disease than young people,” Anderson said. “How
could you imagine a machine as complicated as a person or a
monkey or a mouse, and not have it massively
interconnected?” 

For example, she found that a specific group of microRNAs —
molecules that control gene expression — that she studied in
relation to aging a while back plays an active role in the body’s
response to caloric restriction. Anderson also found links
between caloric restriction and her previous studies on NAD, a
molecule that’s tied to energy metabolism and mitochondria.
Putting these cellular-level studies into a bigger picture allows
Anderson to gauge how all the moving parts come together when
calories are limited. 

“There’s this idea that the constellation of cells in a tissue
are performing different tasks and different ones are creating
vulnerability in different ways,” Anderson said. “It’s
becoming more nuanced, for sure, it’s becoming more complicated.
But it’s also making more sense. Which is why I think it’s kind
of cool.” 

Aging is inevitable, Anderson said, but her work is suggesting
that how you age is flexible and manipulatable. 

Understanding the relationship between metabolism and aging will
allow scientists to better design studies on longevity. And as
more research reveals how and why animals with lower metabolisms
live longer and survive better, scientists may be able to figure
out ways to
mimic those effects in humans.