Fasting and ketones
Mattson and D’Agostino even go so far as to suggest that increased ketone levels boost brain function. Mattson found that ketones in brain tissue stimulate the production of BDNF, the substance that increases the number of mitochondria in the brains of intermittent fasting rats. And D’Agostino was able to show that a ketone ester drink can stabilize the brain chemistry of mice with a genetic disorder associated with seizures: levels of a brain substance called GABA, which has an effect calming on brain activity, increased while levels of another substance called glutamate, which excites brain cells, decreased. “Ketones,” D’Agostino concludes, “return the brain to a normal state.”
Since seizures and poorly functioning mitochondria also play a role in the brains of people with Alzheimer’s disease, Mattson hopes ketones could help here too, and he’s found the first evidence of this in at least one model. murine of the disease in 2019.
Mattson is now also studying possible ketone-related effects on the brain in people who fast intermittently: In one small study, he had 20 overweight and obese people with insulin resistance eating just 500 calories, two days a week. week for two months. The other days, they eat normally. It then examines whether this leads to improvements in brain function and metabolism compared to 20 people on a normal diet.
Perhaps changes in the brain related to ketones could also explain the better ability to concentrate people report when they fast. D’Agostino, for example, remembers writing two grant applications (both successful) and a major publication after a seven-day fast. “Anecdotally,” Mattson confirms, “I get a lot of feedback from people who have switched to intermittent fasting saying they are more productive and focused.” Even the US Air Force and NASA approached him to find out how fasting could allow pilots or astronauts to concentrate for longer periods.
Better concentration is also the reason why Geoffrey Woo, whose company HVNM sells a ketone ester drink, became interested in fasting: in 2016 he founded the WeFast group, which regularly organizes fasting events in Silicon Valley to help people increase their productivity. The group now has more than 20,000 members.
And the series of small, provocative studies on ketones and brain power doesn’t stop. For example, in 2016, Oxford University biochemist Kieran Clarke reported that a diet high in ketones improved spatial learning and memory in rats.
Two years later, Brendan Egan and Mark Evans of Dublin City University found that taking a ketone ester drink prevented an increase in decision-making errors after exercise in sports like soccer. However, Egan points out that in his most recent studies, a ketone drink failed to improve cognitive performance in runners.
Ketones or fasting can also improve exercise performance. Panda mice, for example, ran on treadmills nearly twice as long when fasting 15 hours a day as mice that fasted only 12 hours. And when Clarke fed rats a diet high in ketones for five days, the animals ran 32% farther on a treadmill.
In humans, however, the results are still unclear. For example, Egan found no improvement in endurance performance after taking a ketone drink or after two months of fasting 16 hours each night. On the other hand, Paoli says he has evidence of improved muscle efficiency with long-term fasting. And when Clarke gave eight cyclists a ketone drink with sugar (to achieve ketone levels equivalent to a week of fasting), it improved their endurance in a 30-minute time trial by 2%, or l ‘equivalent to about 400 meters, which is what elite sport makes a clear difference.
Taking a sip of a ketone drink may be easier than a week of fasting, but it comes at a price: 90 milliliters of the HVNM drink with 25 grams of ketones, which is three to seven days of fasting, costs ten U.S. dollars. Nevertheless, top athletes already use such drinks, because taking ketones is not illegal, since ketones are produced by the body itself. Woo says most cycling teams have used the HVNM ketone ester drink before on major European tours such as the Tour de France or the Giro d’Italia.
Nevertheless, the drinks are likely to be too expensive for many normal long-term athletes. And then there’s the taste: when my wife tried the HVNM drink a few years ago while training for the New York City Marathon, she thought it was pretty gross, “like burns from ‘stomach mixed with jelly beans’.