Is intermittent fasting good for longevity?
Intermittent fasting improves health markers such as weight and insulin sensitivity, but whether it also makes you live longer has not yet been proven in humans. It is worth considering, but discuss it with your doctor first if you belong to a risk group.
In animals, intermittent fasting works impressively: mice, but also yeast, worms and fruit flies live longer and stay healthier when they fast periodically. This has been demonstrated in multiple independent studies. But animal research is not human research, and that gap is large here.
In humans, life extension has never been directly demonstrated. There are no large studies showing that people who fast periodically live longer than people who do not. What is reasonably well supported: weight decreases, insulin sensitivity improves, and risk factors for cardiovascular disease are reduced. These effects have been observed in both normal-weight individuals and those with excess weight.
Intermittent fasting also activates a cellular clean-up process called autophagy. In this process, the body clears away damaged proteins and cell components. In animal research, this process protects against age-related diseases such as cancer, Alzheimer's and Parkinson's. Whether it works just as strongly in humans has not yet been sufficiently proven.
One mechanism involved is noteworthy: fasting raises the level of a substance called spermidine, a small molecule that occurs naturally in cells. In multiple model organisms as well as in human volunteers, spermidine rose during fasting and proved to be necessary for the protective effects. Once its production was blocked, those effects disappeared. Note: several authors of this research have financial interests in companies working on related products, which colours the interpretation.
Safety is not a minor issue. Research signals side effects and limitations for specific groups, such as older people and people of certain sexes. Systematic safety research is still lacking. If you start intermittent fasting, be sure to discuss it with your doctor if you take medication, are pregnant, or have a history of disordered eating.
Claims based on PMID 38499159, 27810402, 35310455, 24440038, 39117797, 33512641, 36911497. Financial conflicts of interest have been reported for the spermidine study (PMID 39117797).
Does metformin help you live longer in good health?
For people with diabetes, metformin has a reasonably well-supported health benefit, but as an anti-ageing agent for healthy people it has not yet been proven. Wait for the results of the TAME study before drawing conclusions.
Does rapamycin help people live longer in good health?
Rapamycin works in mice, but whether it also leads to a longer and healthier life in humans has not yet been demonstrated. Side effects are real, long-term data in healthy people are absent, and use outside a clinical context cannot currently be justified.
Is donating blood regularly good for your health?
Regular blood donation is safe for many people, but it can deplete your iron stores, especially if you menstruate or donate frequently. Have your ferritin level checked regularly and discuss your donation frequency with your doctor if you want to become pregnant or are feeling tired.
Can fasting really rejuvenate your cells?
Fasting has clear cell-rejuvenating effects in animal research, but in humans the evidence is still limited to small studies using biomarkers. The most promising findings have not yet been confirmed in large human studies, so caution is warranted.
Does intermittent fasting help your gut health?
For healthy people and people with metabolic syndrome there is reasonably consistent evidence that intermittent fasting has a beneficial effect on gut bacteria and inflammation markers. If you have a chronic bowel disease, discuss fasting with your doctor first, as evidence in that group is still lacking.
What does intermittent fasting do to your insulin sensitivity?
Intermittent fasting improves insulin sensitivity in most people, but be aware of possible muscle loss and hormonal effects, especially if you combine it with intensive exercise.