Season 5 Episode 4 | 4m 38s | Video has closed captioning.
An intermittent fasting diet is one of the hippest new nutrition and fitness philosophies, based around the idea that going hungry can be good for your health. Some think it’s a weight loss secret that calls upon our ancient evolutionary programming. We look at the science behind intermittent fasting.
Aired: 11/30/17
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[MUSIC] Dieting almost never works.
Research tells us eating less and exercising more can help you lose weight at first, but those pounds rarely stay off.
Now some experts think we should focus less on what we eat and more on how often.
Intermittent fasting has become one of the hottest dieting fads out there.
Some health gurus suggest skipping breakfast every day, while others recommend eating only five days a week, limiting yourself to less than 500 calories on the other two.
36 hours might seem like a long time between eating, but In the wild, fasting might actually be more normal than regular meals.
Many predators only eat every few days, and penguins sometimes don't eat for as much as six months each year!
But are the risks of depriving yourself of food worth the health benefits?
What say you, Magic 8-Ball of Science?
In one experiment two sets of mice were given the same high fat diet, but one group was only allowed to eat for eight hours every day.
After 100 days, the mice that fasted weighed less and were in better shape, even though both groups got the same diet!
So what makes skipping meals potentially so healthy?
When you eat, energy is stored as glycogen, mostly in your liver.
Your liver is kinda like the fridge in your kitchen.
Energy is easily added, and, via your daily metabolism, removed.
We convert excess energy to body fat for long term storage - like the freezer in your basement.
But a chemical called insulin regulates access to that long term energy storage.
When we eat, insulin rises, and our cells consume less fat.
When we don't eat, insulin's low, and we can burn those extra pounds.
Not all body fat is bad, but too much is unhealthy.
Why would our bodies have a chemical to stop us from burning it??
The reason is we evolved through periods of scarcity.
Early hunter-gatherers probably ate whenever food was available.
Fasting is an ancient part of who we are.
These days we're surrounded by Big Gulps, Bigger Gulps, and Gulps the literally the size of a human child.
More calories than we know what to do with.
Our bodies are wired to store excess energy for a rainy day, but since we keep eating, that rainy day never comes.
But fasting creates artificial scarcity.
Periods without food lower our insulin, leading to more fat burning, and maybe healthier bodies.
The science is young, but intermittent fasting, might reduce triggers that lead to heart disease, diabetes even cancer.
Short fasts also seem to benefit our brains.
You may think that hunger makes you delirious and stupid or not yourself but fasting can feed our neurons because fat-burning creates chemicals called ketones, which the brain can gobble up.
During periods of regular, intermittent fasting, scientists have even seen growth in brain regions involved in memory.
Imagine your ancestors in an ancient jungle.
It makes evolutionary sense that when we really need to find food, the human brain would be creative and alert.!
There's plenty of fine print., There have been no long term studies that might reveal unknown negative impacts from fasting.
It's unknown how fasting compares with vegan, paleo, raw, keto, or cheeto diets.
Scientists don't know if fasting could trigger eating disorders.
And you shouldn't do it if you're a child, underweight, pregnant, nursing, elderly, or recently deceased.
But for now, we can say fasting probably has benefits - but it hasn't been proven to be any healthier than other diets.
It just seems to work in a special way: by calling on our bodies' evolutionary energy programs.
Maybe the moral of the story is that what we consider when we say "everything in moderation" really isn't moderate when we look at how our bodies evolved!
It's not that food is bad for you.
It's that not eating, sometimes, might be just as healthy.
It's some food for thought.
Stay curious.
