The bottom line on intermittent fasting and brain aging is: The jury is still out. Although a recent review article, published in The New England Journal of Medicine, summarizes the generally positive effects of intermittent fasting on health, findings differ across mice, rat, primate, and human studies.
There is little data on the effect of intermittent fasting on cognitive aging, specifically. It is also still not fully clear whether it is fasting per se, or caloric restriction and/or weight loss that leads to potential benefits.
However, the evidence seems to suggest that fasting periods, in particular, are what lead to change. Fasting causes a metabolic switch from using glucose as fuel to using ketone bodies as fuel, which results in a downstream effect of positive influences on health and aging.
The mounting data on lifestyle factors continues to confirm that diet, exercise, sleep, stress reduction, cognitive and social stimulation all play a role in helping to reduce risk factors for dementia. Intermittent fasting may eventually prove to be another lifestyle choice that can help moderate risk factors.
More research is needed to determine an optimal fasting schedule, such as:
- 5:2, when people consume a certain number of calories for five days a week and a much-reduced caloric intake for two days
- Daily fasting during a certain number of hours; 8:16, when people restrict eating to 8-hour intervals and fast for 16 each day, is especially popular.
In a society ingrained with three meals a day plus snacks and a strong eating culture, such restriction may be difficult and unsustainable. Practitioners also need more information as to which fasting schedule to prescribe and how to help people adhere. As with all lifestyle changes, adapting in moderation may be best. For example, a person could try fasting for 12 hours a day and gradually make this fasting period longer.
So, should we try this at home? If the literature convinces you, then I would consider trying small steps towards this goal and always in consultation with a physician and careful monitoring to determine any effects, positive or negative.
Does the literature convince me? Not sure yet, but I’m sure that I am also among the resistant to changing my eating patterns, especially without hardcore evidence.
In studies of human beings, genetics and other factors do also play a role in healthy aging. Lifestyle factors can help moderate risk, but may not be cures, which is why some people may develop dementia even though they have always seemed to be doing all the “right” things. Taking steps towards lowering risk factors is a “no-brainer” (pardon the pun!), but the path there may be different for each of us.