New Yorkers are born tough, but not Stone-age tough. Our ancestors were hunter-gatherers who often went periods of time without food while foraging. Humans had adapted to the unpredictability of getting their next meal.
But now we have “evolved” to expect three square meals a day, not to mention snacks.
“Weight loss has become a cultural obsession,” says Jennifer Cholewka, RD, CNSC, CDN, Clinical Nutrition Coordinator at The Mount Sinai Hospital. “And intermittent fasting is a trending topic. But it has roots in how we have evolved as human beings.”
Scientists are discovering that our bodies adapt to intermittent fasting in ways that our ancestors did. And according to a recent article in The New England Journal of Medicine, fasting has health benefits that extend far beyond weight loss. It seems that “when” we eat can be just as important as “what” we eat.
What is intermittent fasting?
With intermittent fasting, there are scheduled times when you eat and times when you don’t. Medical researchers have studied three approaches and shown them to be effective.
Daily time-restricted feeding means narrowing the time you eat to a shorter period of time during the day, usually eight hours. The time that you’re fasting is 16 hours each day. So you might stop eating at 8 at night, and not eat again until noon the next day. After 10-12 hours, your body throws a “metabolic switch” and you start burning through the glucose stored in your body. Your liver stores about 700 calories of glucose, and once gone, your body starts burning away that hard-to-get-rid-of belly fat.
5:2 intermittent fasting means that you eat as you normally do, five days a week. On the other two days, you only eat one moderately-sized meal. The two days that you’re fasting should not be consecutive. And your goal should be one 500-calorie meal on those days. You could work up to this gradually, by starting with one day a week. Your meal on that day could be 1,000 calories. Try that for a month, and then extend it during the second month to two days a week. The next month, reduce your meals to 750 calories. And then the next month, shoot for 500 calories.
Alternate day fasting is the most extreme version. On the days that you eat, keep it to a 12-hour window. Then you will fast that night and not eat anything the next day. It’s important to note that you can drink as much water as you want, and also tea and coffee if you don’t add any calories like milk, half-and-half, or sugar. You can also take vitamins, supplements, and of course, your normal meds. Talk to your doctor though, because certain meds and supplements need to be taken with food. So your plan might be to eat Sunday, Tuesday, Thursday, and Saturday. And then the next week, it would be Monday, Wednesday, and Friday.
What’s the payoff?
As if being svelte wasn’t enough, the benefits of intermittent fasting cited in The New England Journal of Medicine include:
• Cancer prevention
• Cellular and DNA repair
• Diabetes prevention and improvement
• Prevention of heart disease and stroke
• Greater mental acuity and brain health
• Greater muscle endurance
Some of these benefits are related to weight loss. Intermittent fasting increases your metabolism so you burn more calories, and it tends to target fat around the central organs. Belly fat is worse for the heart and causes inflammation. And less cholesterol means less heart disease and risk of stroke.
But once your “metabolic switch” kicks in, there are a host of other benefits. Once your body runs out of glucose, it starts converting ketone bodies from the liver for fuel. And this causes a wave of other changes throughout the body, because ketone bodies aren’t just fuel, they give orders to a variety of other cells and molecules that can affect health.
Scientists have been looking at the relationship between intermittent fasting and cancer in animals for quite a while. Calorie restriction or alternate day fasting has been shown to slow the growth of many tumors and increase their response to chemotherapy and radiation. Studies on humans are promising, but care must be taken to avoid malnutrition. Consultation with your doctor is key.
Another process triggered by the ketone bodies is called autophagy, which repairs the normal cells in the body. It’s like cellular house-cleaning, where the cells get rid of old proteins. Studies on both humans and animals demonstrate physical benefits. In one study, young men who fasted for 16 hours lost fat while maintaining muscle mass over a period of two months of resistance training. Balance, coordination, and endurance all improved in animals during fasting studies.
Brain power gets a boost, too. Verbal memory, spatial cognition, short-term and associative memory are all improved with humans in fasting studies. This is powerful news for the prevention of Alzheimer’s and Parkinson’s diseases. Neurological benefits have also been documented for multiple sclerosis and rheumatoid arthritis.
What’s the downside?
To gain the benefits, intermittent fasting isn’t a quick fix; it’s a lifestyle. Maintaining periods of not eating can be hard to stick to. But starting with a gradual program and working up to longer periods of fasting can help. In the beginning, you can expect to feel hungry, but science tells us that this is as much psychological as physiological. Drinking water when you feel hunger pangs can trick your body into feeling full. You might feel a bit foggy—but good news, black coffee and tea are your friend. And of course, if you’re under any type of medical treatment such as chemotherapy, consult your doctor first.
Throughout history, spiritual literature is full of examples of people who fasted for purification. On the basis of the latest research, it seems that the glow of health is here for modern-day fasters.