CHICAGO (CBS) -- For several days a week, Pernu Menheer gives up food; not just because he wants to lose weight, but because he wants to boost his brain power and productivity.
Menheer says goodbye to the food on his plate and consumes just coffee, tea, or water for 20 to 30 hours at a time.
"I wake up kind of jumping out of bed," he said of his intermittent fasting.
Menheer said he started fasting every other day to lose a few pounds, but felt increased energy and focus after he started.
"It actually really does help with my concentration," he said. "It's just like I'm on a roll right now. I'm just going to keep on coding until I am done, or until I run out of gas."
The trend is especially popular in Silicon Valley, where executives fast days at a time and boast how it increases their brains' creative potential.
"They are doing it … to give themselves a performance boost, almost like steroids for the brain," said Dr. Jason Fung, who is an international lecturer on intermittent fasting.
Fung said it's not true that fasting is a drain on the human body.
"The way that the human body works is that we store food energy for when we don't eat," he said.
Fung pointed to studies that conclude fasting slightly increases metabolism for weight loss, but also revs up brain hormones that make us feel better, and helps the liver produce molecules called ketone bodies to break down stored fat for energy.
"Some people feel that these ketone bodies are a much more efficient fuel for the brain," he said.
Dr. Krista Varady, a nutritionist at the University of Illinois at Chicago, said intermittent fasting generally is not dangerous. Varady said she has studied more thant 500 intermittent fasters who consume only 500 calories every other day.
"Just hearing from our subjects as they start the diet, they really feel like they have more focus, and that they actually have a boost of energy," Varady said.
However, Varady cautioned extreme fasting for prolonged periods could lead to decreased bone and muscle mass if you aren't careful.
"Not eating for half the week, it doesn't seem like a great idea," she said.
In spite of the benefits he feels, Menheer warned intermittent fasting isn't easy.
"When I get those little hunger pains, I already know that I'm going to ignore it," he said.
No one should begin a fasting regimen without first consulting their doctor. It's also discouraged for the elderly, people with eating disorders, and pregnant or breastfeeding women.
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