Fasting for health: the science behind this growing trend

Mimi Dexter-El has not had breakfast in over two years.

That means walking by her mother cooking breakfast each morning, “smelling the wonderful aromas” of onions, eggs and other delicious breakfast food, and not eating any of it. 

Dexter-El is a big proponent of what’s called intermittent fasting. She even has a blog and Facebook page devoted to the topic.

There are several ways to do it. Some people don’t eat anything a couple of days a week. Others eat every other day or limit their caloric intake on certain days (as has commonly become known as the 5:2 diet). Some limit eating to a specific time each day. For Dexter-El, who’s 47 and works in marketing in Phoenix, that window is between 5 and 10 p.m.

It means that during lunch time, instead of heating up her lunch, she might just sip on white tea.

“It’s pretty amazing that your brain and your mind can really work to fuel itself sufficiently,” she said.

Intermittent fasting has been growing in popularity in recent years, with several high profile celebs jumping on board. And if you believe the hype about this no-cost approach, there could be all sorts of health benefits, from preventing Alzheimer’s disease to combatting arthritis.

While a growing body of research is pointing to some positive effects, especially in people who are obese, studies on the long term impact in humans are still early, with most research coming out of animal studies.

Critics worry such an approach overlooks other important healthy habits.

Yo-yo’ing on other weight loss diets

Dexter-El says she tried a bunch of different diets and exercise approaches but none seemed sustainable.

“You know, usually I would lose the weight and then gain it all back, and then some,” she said.

Then a couple of years ago, she realized things were really getting out of control. She was 44 years old and at 5’5,” weighed 237 pounds. She worried about following in the path of her father, who, for years, did not control his diabetes.

“He has had a few amputations. He’s blind,” she said. “And that definitely scared me straight.”

At first Dexter-El says her doctor was wary of the fasting approach, but he saw her weight and bad cholesterol dip.

“My numbers just improved in every area so he eventually kind of came around to it,” she said.

So are a number of other doctors and scientists.

Studying the impact on obesity and other inflammatory diseases

One even quotes a famous 19th century writer to prove his point.

“‘A little starvation can really do more for the average sick man than can the best medicines and the best doctors,'” said Dr. Mark Mattson, quoting Mark Twain.

Dr. Mattson, a professor at Johns Hopkins and head of the neuroscience lab at the National Institute on Aging, says for most of human history, we needed to be able to fast.

“Our ancestors, undoubtedly before agricultural revolution, had to go extended periods of time without food,” he said.

People had no choice but to adapt. Those who couldn’t function efficiently on an intermittent diet, and even excel, would probably die.

But Mattson is going beyond these evolutionary theories and Mark Twain quotes.

He has been studying the effects of intermittent fasting on the brain and the body, and says the first thing that happens during an intermittent fast is the body starts burning fat, instead of sugar.

“What defines fasting is a switch in the source of the energy in our bodies from glucose that’s released from the liver to mobilization of fats from fat cells,” he said.

Sounds great if you’re trying to lose weight, right? Mattson thinks there are even more potential benefits.

“In all our organ systems – essentially the heart, muscle and liver – one thing that happens is there’s reduced inflammation,” he said.

And, reduced inflammation in the body is a good thing. It means healthier cells. Mattson says those healthier cells in the brain could mean better cognition and possibly protection from diseases like Alzheimer’s and Parkinson’s. He’s testing this out right now in a study of older adults.

Nutritionists, however, like Stella Volpe at Drexel University is not on board.

“It really is not something that I would encourage people to do,” said Volpe, adding that she worries fasting could be harmful. “From a standpoint of what the body needs, that there’s no reason, scientifically, why a person would do that, at least not at this time.”

Volpe points to the lack of long term, scientific studies on the effects of fasting in humans, and she thinks it overlooks the importance of consistent, healthy eating practices.

“It’s not teaching them good, healthy eating practices and behaviors, to be somewhat consistent in their eating behaviors and snacks throughout the day,” she said.

Wrapping up for the day

Still for fans of intermittent fasting, they say it’s working for them. Mimi Dexter-El would welcome more science to back up what she’s doing, but she doesn’t see any reason to stop, even when fasting has it’s moments, like in the middle of the afternoon.

“Right now, I’m feeling a little tired,” she said around 2 p.m. on a recent work day.

She hadn’t eaten anything in 17 hours.

“I’m still going to push through. It gets easier and easier the longer I do it.”

And before she knows it, 5 p.m. hits and it’s time to eat. She scans the fridge and settles on some papaya. She heats up some leftover stew. Later on, she snacks on some popcorn and has a couple pieces of candy.

And that’s it.

“It really wasn’t too hard,” she said around 9 p.m. “We start all over again tomorrow.”