Do your cells actually get younger when you restrict calories?
Calorie restriction demonstrably slows the biological rate of ageing in cells, including in people. An approach such as the fasting-mimicking diet, eating less for five days per month, is more achievable for many people than daily calorie restriction and showed measurable improvements after just three months.
Calorie restriction slows the biological rate of ageing in multiple studies involving people. In one large study, 218 healthy people ate fewer calories for two years. Their cells were measurably ageing more slowly afterwards. This is the strongest direct evidence in people to date.
In rats, calorie restriction shows even broader effects: ageing-related changes in the make-up of cells and the signals cells send to one another that drive inflammation are partly reversed. Whether this works just as powerfully in people is not yet certain, but it does suggest how calorie restriction might be working.
A fasting-mimicking diet (five consecutive fasting days per month, for three months) lowered several risk factors at the same time in 100 healthy adults: blood pressure, fasting blood sugar, markers of inflammation, and fat levels in the blood. The effect was greatest in people who already had slightly elevated values. This is not a direct measure of cellular age, but of demonstrable health-related changes.
Epigenetic clocks measure how fast cells are ageing based on chemical tags on the DNA. Several small studies in people suggest that calorie restriction or a Mediterranean diet influences the readings of such clocks in a favourable direction. An important caveat applies here: in two reviews, the authors had commercial interests in companies that sell these clocks. Furthermore, it has not yet been proven that a lower clock reading actually means a longer life or less disease.
Of all dietary strategies, calorie restriction and intermittent fasting have the broadest support from studies in mammals, including monkeys. Other approaches such as a ketogenic diet or specific supplements look promising in studies examining how they might work, but so far have little direct evidence in people. Strictly restricting calories is hard for most people to keep up; the fasting-mimicking diet is a researched alternative approach with a lower barrier to entry.
This answer draws on two studies in people in which participants were assigned to different groups (including one large study with 218 participants), a study in which participants were assigned to a fasting-mimicking diet (100 participants), a review combining 13 studies, and several review articles covering animal and lab-based research. The human evidence for a slowing of the biological rate of ageing is encouraging but still limited in scale and duration. A relevant point: in two of the reviews, the authors had financial ties to companies selling biological age tests, which slightly colours the interpretation of those specific sources. In addition, the real-world meaning of a lower score on biological age tests has not yet been established: it is not proof that people live longer or in better health.
Can you really lower your biological age, and does research support this?
There are promising hints that biological age is measurable and perhaps steerable, but this has not been proven. Wait for larger studies in people before basing major decisions on this.
Is it true that women age more slowly biologically than men?
Multiple studies confirm that women are biologically younger than men of the same age, but women also spend their extra years more often in poorer health. The difference is therefore real, but more complex than the simple conclusion that 'women age more slowly'.
Does your biological age change differently at night than during the day?
The night is biologically not a pause but an active recovery phase, and that phase deteriorates noticeably with age. Those who protect their sleep rhythm, with fixed times, limited screen use before bedtime and a longer nightly eating break, preserve that recovery function for longer.
Can nucleotides lower your biological age?
NAD+ supplements measurably raise NAD+ levels in your blood and, in one study, prevented biological age from rising, but did not actively lower it. The evidence is still too thin for firm conclusions, but 600-900 mg of NMN per day appears safe and also improved walking ability in that same study.
Does calcium-AKG lower your biological age?
Reliable evidence that calcium AKG lowers biological age in humans is lacking. The well-known claim of 8 years comes from a small study without a placebo group, conducted by researchers with a commercial interest. Wait for the results of the ongoing independent study before drawing any conclusions.
Does your biological age advance more quickly when you are lonely?
Loneliness is associated with measurably faster biological ageing, and that association has been found across multiple independent measures. Whether loneliness directly causes this has not yet been proven, but the evidence is strong enough to take social connection seriously as part of healthy ageing.