Is a low-carbohydrate or ketogenic diet good for living longer?
A ketogenic diet can help with weight problems and metabolic disorders, but for people who simply want to live longer and stay healthy, no proven advantages over a varied diet have been demonstrated. Those who exercise intensively may even be at a disadvantage.
Several studies point to interesting mechanisms: a ketogenic diet influences processes that play a role in ageing. But a second body of evidence quickly dampens the enthusiasm. The effects differ greatly depending on the disease and the specific version of the diet, and solid proof that such a diet actually extends lifespan in people simply does not yet exist.
The strongest evidence concerns weight and metabolism. Ketogenic diets demonstrably help with weight management, metabolic syndrome, and insulin resistance. The so-called Spanish ketogenic Mediterranean diet showed strong improvements in metabolic markers, with the added benefits of preserved muscle mass and reduced hunger. Whether those improvements also lead to a longer life has never been demonstrated.
There are also risks. A high protein intake, typical of this diet, increases the burden on the kidneys' filtering capacity. Over the long term, this can cause chronic kidney damage, even in people without a pre-existing kidney condition. Animal protein appears to be more harmful in this respect than plant protein. Long-term studies in people are still lacking.
For specific diseases, the picture is mixed. In cancer, everything depends on the tumour type and there is no consensus. In Alzheimer's disease, the diet restored memory in mice, possibly through a specific ketone compound, but this has not yet translated to people. In multiple sclerosis, small early studies found the diet to be safe, but evidence of effectiveness in people is absent.
If you combine a ketogenic diet with intensive exercise, there is a concrete drawback. For high-intensity training, such as CrossFit, a carbohydrate-rich diet performs better. Because intensive exercise is itself one of the strongest protectors of a long, healthy life, this is a practically important point.
All claims come from combined study reviews and animal studies. There are no large long-term studies in people that use lifespan as a measured outcome. The evidence for short-term metabolic benefits is reasonable, but for longer life specifically it remains limited and indirect.
Does eating less help you live longer?
In laboratory animals the effect on lifespan is well established, but in healthy humans direct evidence is lacking. A moderate and sustainable eating pattern is wiser than extreme restriction; discuss major changes to your diet with a dietitian or doctor.
Which diet is best supported by evidence for a long, healthy life?
For anyone looking to use diet to invest in a long and healthy life, the Mediterranean diet is currently the best-supported choice. Large human studies consistently show positive effects on both cardiovascular health and cognitive health.
Do you actually live longer if you structurally eat fewer calories?
In laboratory animals, eating less convincingly extends lifespan, but this has not yet been demonstrated for healthy people without excess weight. If you want to benefit from what has been shown, eating moderately less or following an interrupted eating pattern are the safest, most reasonably supported options.
Do you live longer on a vegetarian or plant-based diet?
A good-quality plant-based diet is linked to fewer early deaths. But strictly vegetarian or vegan eating has not been proven to be better than a varied diet that includes occasional meat or fish.
Does the Mediterranean diet help you live longer?
In large population studies, the Mediterranean diet is consistently linked to a lower chance of dying and less heart and blood vessel disease; those who want to follow the diet as a whole have the strongest evidence on their side.
Does the timing of your meals affect how long you live?
The timing of your meals is associated with biological ageing and risk of death, but cause and effect have not been proven. Eating early, a nightly fasting window of at least 13 hours and a regular eating pattern appear to be the best choices based on what is currently known.