Is a low-carbohydrate or ketogenic diet good for longevity?
A ketogenic diet can help with weight problems and metabolic disorders, but for people who simply want to live longer and healthier, no proven advantages over a varied diet have been demonstrated. Those who exercise intensively may even be at a disadvantage.
Reviews point to interesting mechanisms: a ketogenic diet influences pathways that play a role in ageing1. But a second review immediately tempers the enthusiasm: effects differ greatly depending on the disease and the dietary variant, and hard evidence that such a diet genuinely extends lifespan in humans simply does not yet exist2.
The strongest evidence concerns weight and metabolism. Ketogenic diets demonstrably help with weight management, metabolic syndrome and insulin resistance3. The so-called Spanish ketogenic Mediterranean diet showed strong improvements in metabolic markers, with the added benefits of muscle preservation and reduced hunger. Whether those improvements also lead to a longer lifespan has never been demonstrated.
There are also risks. A high protein intake, typical of this diet, increases the load on the kidney filters. This is called hyperfiltration, and over the long term it can cause chronic kidney damage, even in the absence of pre-existing kidney disease4. Animal protein appears to be more harmful in this regard than plant protein. Long-term studies in humans are still lacking.
In specific diseases the picture is mixed. In cancer, everything depends on the tumour type and there is no consensus5. In Alzheimer's disease, the diet restored memory in mice, possibly via a specific ketone compound, but this has not yet been translated to humans6. In multiple sclerosis, small pilot studies found the diet to be safe, but evidence of effectiveness in humans is lacking7.
If you combine a ketogenic diet with intensive exercise, there is a concrete disadvantage. During high-intensity training, such as CrossFit, a high-carbohydrate diet performs better8. Since intensive exercise is itself one of the most powerful protectors of a long, healthy life, this is a practically important point.
All claims are derived from reviews, scoping reviews and mouse studies. There are no large long-term studies in humans that use lifespan as an endpoint. The evidence for short-term metabolic benefits is reasonable, but for longevity specifically it remains limited and associative.
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 high-quality plant-based diet is associated with less premature death. However, eating strictly vegetarian or vegan has not been proven to be better than a varied diet that occasionally includes meat or fish.
Does the Mediterranean diet help you live longer?
The Mediterranean diet likely lowers your risk of heart disease and premature death. But anyone who truly wants to live longer needs more than a good dietary pattern alone: physical activity, not smoking and social connection count at least as heavily.
Are beans and legumes good for longevity?
Large observational studies consistently show that people who eat more legumes have a lower risk of death. For most people, a daily serving of legumes is well supported by the evidence; older adults should also pay attention to getting sufficient protein overall.