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Daphne Koller, the head of Google’s life extension
spinoff Calico, recently discussed some of her unpublished
Placing animals on restricted diets appears to improve
their health and may even play a role in lengthening their
The first clinical trial of this approach in people
suggests it could have benefits as well, but more studies are
It’s not every day that the head of Google’s shadowy
life-extension spinoff offers a peek at her unpublished research.
But earlier this month, Daphne Koller,
Calico’s chief computing officer, announced at a conference in
San Francisco that she and her team have been studying what
happens to mice when they’re placed on restricted diets.
Koller explained that limiting how many calories the mice
consumed appeared to help with certain measures of aging — a
finding that’s been bolstered by a spate of recent studies in
“Caloric restriction is the one intervention that’s been
repeatedly demonstrated to extend lifespan across multiple
species,” Koller said.
Until recently, those findings had been limited to animals. But a
new paper suggests they might also apply to people.
The first clinical trial of caloric restriction on humans
Researchers published the results of the first-ever clinical
trial of caloric restriction in humans in the Journals
of Gerontology. Their takeaways were overwhelmingly positive.
study, roughly 200 non-obese people aged 21-51 were randomly
assigned to either eat as they normally did or to eat 25% fewer
calories than usual for two years. By the study’s end, the
dieters saw some hopeful health indicators, like dips in their
cholesterol and blood pressure, and more control over their blood
The dieters also lost an average of 15 pounds and kept it off — a
positive finding that’s rarely seen in weight loss studies.
“To our knowledge, no previous study in any population, not to
mention a normal weight population, has demonstrated this degree
of sustained calorie restriction and weight loss for this length
of time,” the scientists wrote.
Still, the study was preliminary and designed mostly to see if
people could stick to the diet in the first place. Sure enough,
82% of the participants stayed with it for the full two years.
What remains to be seen is whether the beneficial effects they
observed, like lower cholesterol and blood pressure, translate
into the actual health outcomes they were looking for, like a
reduced risk of disease or, most importantly, a longer life.
Studies in monkeys and mice suggest they might.
Monkeys and mice on restricted diets have younger-looking cells
Various parts of monkey and mice bodies are strikingly similar to
those of humans. So a spate of research suggesting the animals’
lives could be extended by putting them on diets has been met
A September study published
in the journal Nature found that dieting rhesus monkeys had
cells that appeared, on average, seven years younger than their
actual age. The monkeys’ diets had been restricted by 30% for
two-thirds of their lives, starting when they were middle aged.
Mice were also examined in that study — after eating 40% fewer
calories for nearly their entire lives, the mice’s cells appeared
two years younger. That’s actually a slightly more pronounced
outcome when you take into account the average lifespans of the
two animals (35 years for the monkeys and 2-3 years for the
Still, saying cells “looked younger” doesn’t tell the full story.
To assess how the dieting impacted the way the animals aged,
researchers looked at an important genetic
process called methylation that is likely linked with aging.
When the animals were placed on strict diets for long periods of
time, that appeared to interfere with the typical methylation
process. It was as if someone had tossed a brake into the
spinning gears of their biological clocks.
Still, methylation is not yet considered a gold standard for
measuring aging. There’s still a lot we don’t know about the
process, such as whether it effects all types of cells equally
and if it can be used as a metric across different kinds of
“Ultimately what these studies show is that what you eat
influences how you age, and it’s not all bad news,” Rozalyn
M. Anderson, who leads an aging research program at the
University of Wisconsin-Madison and co-authored the latest paper,
said in a statement.
Perhaps Calico has some more definitive findings up its sleeve.