Fat cells (artificipartner coloured). Recut offeive diets cainclude overweight loss and lengthen life, but the two effects are not necessarily connected.Credit: Steve Gschmeissner/SPL
Cutting calorie inget can direct to a leaner body — and a prolongeder life, an effect standardly chalked up to the weight loss and metabolic alters caincluded by consuming less food. Now, one of the biggest studies1 of dietary recut offeions ever carry outed in laboratory animals contests the conservative wisdom about how dietary recut offeion increases prolongedevity.
The study, involving csurrenderly 1,000 mice fed low-calorie diets or subjected to standard bouts of speedying, create that such regimens do indeed cainclude weight loss and joind metabolic alters. But other factors — including immune health, genetics and physioreasonable indicators of resiliency — seem to better elucidate the connect between cutting calories and incrrelieved lifespan.
“The metabolic alters are meaningful,” says Gary Churchill, a moinclude geneticist at the Jackson Laboratory in Bar Harbor, Maine, who co-led the study. “But they don’t direct to lifespan extension.”
To outside spendigators, the results drive home the intricate and individualized nature of the body’s reaction to caloric recut offeion. “It’s revelatory about the complicatedity of this intervention,” says James Nelson, a biogerontologist at the University of Texas Health Science Cgo in in San Antonio.
The study was unveiled today in Nature by Churchill and his co-authors, including scientists at Calico Life Sciences in South San Francisco, California, the anti-ageing cgo ined biotech company that funded the study.
Counting calories
Scientists have prolonged comprehendn that caloric recut offeion, a regimen of prolonged-term confines on food inget, lengthens lifespan in laboratory animals2. Some studies3,4 have shown that intermittent speedying, which retains foolishinutive bouts of food deprivation, can also incrrelieve prolongedevity.
To lachieve more about how such diets toil, the researchers watched the health and prolongedevity of 960 mice, each a geneticpartner contrastent individual drawn from a diverse population that mirrors the genetic variability create in humans. Some mice were placed on calorie-confineed diets, another group trailed intermittent speedying regimens, and others were allowed to eat freely.
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Cutting calories by 40% produceed the prolongedest prolongedevity bump, but intermittent speedying and less cut offe calorie recut offeion also incrrelieved mediocre lifespan. The dieting mice also distake parted favourable metabolic alters, such as reductions in body overweight and blood sugar levels.
However, the effects of dietary recut offeion on metabolism and lifespan didn’t always alter in lockstep. To the authors’ surpascend, the mice that lost the most weight on a calorie-confineed diet tfinished to die youthfuler than did animals that lost relatively unpretentious amounts.
This recommends that processes beyond straightforward metabolic regulation drive how the body reacts to confineed-calorie regimes. What mattered most for lengthening lifespan were traits joind to immune health and red-blood-cell function. Also key was overall resilience, presumably encoded in the animals’ genes, to the stress of shrinkd food inget.
“The intervention is a stressor,” Churchill elucidates. The most-strong animals lost the least weight, persisted immune function and lived prolongeder.
Leanness for prolongedevity
The discoverings could reshape how scientists skinnyk about studies of dietary recut offeion in humans. In one of the most comprehensive clinical trials of a low-calorie diet in well, non-overweight individuals, researchers create5 that the intervention helped to dial down metabolic rates — a foolishinutive-term effect thought to signal prolongeder-term advantages for lifespan.
But the moinclude data from Churchill’s team recommend that metabolic meastateivements might echo ‘healthspan’ — the period of life spent free from chronic disrelieve and disability — but that other metrics are demanded to say whether such ‘anti-ageing’ strategies can truly extfinish life.
Daniel Belsky, an epidemiologist who studies ageing at the Columbia University Mailman School of Public Health in New York City, alerts aachievest over-extrapolating from mice to humans. But he also accomprehendledges that the study “inserts to the increaseing empathetic we have that healthspan and lifespan are not the same skinnyg”.
