Fasting diets may boost brain power

Intermittent fasting may provide your brain with more energy, improving memory and learning capabilities, according to a new study. 

Researchers from the National Institute on Aging found that when mice were fed every other day, they grew more neurons and synaptic connections, improving their cognitive functions.

The new findings support previous research showing the health benefits of fasting for age-related and cardiovascular diseases. 

During intermittent fasting, the body switches energy sources from glucose, made in the liver, to fat cells, which stimulate activity and cell growth in the brain, according to the study. 

Eating on an intermittent fasting schedule could encourage the growth of new neurons, improving memory, learning and cognition, according to a new study 

The body runs off of the liver’s energy stores for about 10 to 14 hours in humans, says Mark Mattson, chief of the laboratory of neurosciences at the National Institute of Aging.

‘When those stores are out, human, as well as animal bodies switch to fat stores, which are converted into compounds called ketones in the blood. 

The principle is essentially the same one behind popular keto diets, which also put the body in a ‘starvation’ state, encouraging it to draw on fat cells – rather than glucose – for energy.

‘Ketones act directly on the nerve cells to stimulate production of BDNF’ – a key protein to neuron growth – ‘and may help optimize cognition, learning and memory building,’ says Dr Mattson. 

The result, which he and his team observed in mice, is better mental function, lasting a week or two. 

‘It’s a little like exercise,’ he says, ‘if you don’t keep doing it, you lose the effects.’ 

In fact, the phenomenon is analogous to exercise in number of ways. 

‘If you think in terms of aging…say between ages 30 and 40 you did exercise, then, you quit. You still accrue benefits in sort of delaying the onset of age-related disease,’ Dr Mattson says. 

The same may be true for regular bouts of intermittent fasting for mental functioning, but research has yet to bear the theory out.  

Simply eating less will not have the same effects, however. 

 We evolved to eat intermittently, and it’s important that the brain function well – perhaps even optimally – when we haven’t been able to eat for an extended time period

Dr Mark Mattson, neuroscience laboratory chief at the National Institute on Aging

‘People who eat three meals a day but have an overall relatively low calorie intake – between 1,800 and 2,000 every time they eat a meal – replenish their liver energy stores. 

‘So they may go six hours between meals, but that’s not enough to elevate ketones,’ says Dr Mattson. 

In animal studies, like his, the benefits of fasting were ‘independent of overall calorie intake,’ he says, but the ‘metabolic switch from glucose use to ketones, we think, is really important to the health benefits.’ 

The crucial neuron growth happens in the ‘resting’ period between fasting bouts, but there are brain benefits during the scarce times as well. 

The mice in the study were more alert and showed more activity in the areas of their brains responsible for learning and memory during the fasting period. This is an important survival function.   

‘One would assume that in evolution, individuals whose  brains did not function well in fasting state were likely not to survive,’ says Dr Mattson, ‘so, we evolved to eat intermittently, and it’s important that the brain function well – perhaps even optimally – when we haven’t been able to eat for an extended time period.’

Dr Mattson says that the every-other-day fasting his team used for the mice probably wouldn’t work for people, but previous research has shown that subjects adjust relatively easily to the increasingly popular 5:2 fasting regimen, which requires  two days of fasting each week.

Another ongoing study is now measuring how intermittent fasting on the 5:2 plan might be beneficial for obese people who are ‘at risk of cognitive impairment because of their ages and metabolic statuses,’ says Dr Mattson.