Researchers at Calico Life Sciences and the Jackson Laboratory profiled more than a thousand molecules in the blood of 960 genetically diverse mice across their whole lives, under five different feeding regimens ranging from unrestricted eating to 40 percent calorie cuts. They found that intermittent fasting and chronic calorie restriction push blood chemistry in the same direction, that the change gets bigger the more food is withheld, and that aging in the blood is not a smooth slope but two phases, with a sharp handover into terminal decline at about 85 percent of a mouse’s natural lifespan. Two proteins, an antioxidant enzyme called SODE and an inflammation marker called VCAM1, stood out as the best blood-based predictors of how long an individual mouse had left.
For nearly a century, cutting calories has been the most reliable way to make an animal live longer. What has stayed frustratingly murky is what actually changes in the body to make that happen. A new preprint from Calico Life Sciences and the Jackson Laboratory takes one of the most detailed looks yet, tracking 1,512 metabolites, lipids and proteins in the blood of 960 genetically diverse female mice followed from mid-life to natural death.
The headline idea is that the blood carries a readable signature of both diet and aging, and that the two partly oppose each other. Molecules that climb with age tend to be pushed back down by dietary restriction, and molecules that fall with age tend to be lifted. Restriction, in other words, appears to partially rewind the blood’s aging signature rather than simply slowing the clock.
Two other findings stand out. First, it barely matters whether food is withheld by fasting for a day or two a week or by chronically eating less. Both routes converge on the same molecular program, and the size of the shift scales with how many calories are cut. Second, aging in the blood is biphasic. For most of life the chemistry drifts gradually, then near 85 percent of a mouse’s lifespan it lurches into a distinct terminal phase marked by the spillage of intracellular debris into the circulation, a signal the authors interpret as cellular breakdown rather than healthy aging.
By deliberately excluding that dying window, the team searched for honest predictors of remaining life. Two proteins survived two independent statistical approaches: SODE, an antioxidant enzyme that restriction actively raised, and VCAM1, an inflammation and vascular aging marker that diet barely touched. The implication is that at least two separate biological routes, one metabolic and diet-responsive, one immune and largely diet-independent, run in parallel toward longevity. The work is a resource rather than a therapy, but it sharpens where to look. [Confidence: Medium]
Actionable Insights
This is a mouse plasma resource, not a human trial, so every take-home is a hypothesis rather than a prescription. With that caveat, the practical signals are as follows.
Degree of restriction matters more than method. In the parent cohort, 40 percent calorie restriction produced the largest lifespan gain, a median increase of roughly 36 percent, about 9 months on top of a 765-day baseline. The mildest intervention, fasting one day a week, barely reduced net calories (a 3 percent change) and moved only about 5 percent of measured molecules, versus 40 percent of molecules shifted under 40 percent restriction. Effect size scales with calorie deficit, not with the fasting schedule itself.
Candidate biomarkers to watch, not to chase: adiponectin rose under all four restriction regimens and falls with age, making it a plausible readout of a restriction-like state. Higher SODE and albumin, and lower VCAM1 and LRG1, tracked longer remaining life. Complement and other inflammation markers fell with restriction, consistent with reduced inflammaging.
Realistic magnitude check: even the best blood-protein model explained only about 10 percent of the variance in remaining lifespan, so no single marker is close to a reliable clock.
Context and Source
- Open access preprint paper: A multiomic lifespan signature in genetically diverse, diet-restricted mice. Posted to bioRxiv on 27 July 2026
- Institutions: Calico Life Sciences LLC (South San Francisco, California, USA) and The Jackson Laboratory (Bar Harbor, Maine, USA). Country: United States.
- Journal and impact evaluation: This is a bioRxiv preprint that has not been peer reviewed.