Fast to Last

Eat less to live longer

Fasting is a hot topic these days, but in reality, it has been part of our lifestyle in some form or another for most of human history. The primary difference between now and then is intentional versus unintentional. The incredibly plentiful times we live in provide non-stop food consumption at our fingertips, which is relatively new in the overall picture of our evolution.

While recorded human history goes back about 5,000 years, estimates put the appearance of the first homo sapiens approximately 200,000-300,000 years ago. Food on demand has only been part of our equation for about the last 150 years…which is a relatively short amount of time in the grand scheme of things. Whether due to necessity, circumstance, or ritual, for most of human history, going long periods between eating was commonplace.

These days, we think going a couple of hours without putting something in our mouths is inhumane. I remember one time, years back when we took our young son to the movies. It suddenly hit me how crazy it was that people feel the need to eat through a movie—not just a little tea sandwich, but ginormous buckets of popcorn and equally huge cups of soda, mostly right after lunch or dinner. It’s kind of crazy if you really think about it.

The contrast between hunter-gatherer times and now got me wondering if many of our ailments could possibly be due to the relatively little evolutionary time that our bodies have had to adapt to these harmful 24/7 food options. Combined with the abundance of empty-calorie choices, we have gotten so far off track in our eating habits as a society that it’s no wonder we are seeing a renewed interest in fasting as another tool in the diet toolbox.

Beyond weight loss 
But the benefits of fasting go beyond possible weight loss. The more enduring advantage of some calorie restriction is its impact on longevity. Benjamin Franklin wisely said, "To lengthen thy life, lessen the food." More recently, David Sinclair, the founding director of Harvard’s Center on Aging Research, wrote: “After twenty-five years of researching aging and having read thousands of scientific papers, if there is one piece of advice I can offer, one surefire way to stay healthy longer, one thing you can do to maximize your lifespan right now, it’s this: eat less.”

Although most fasting studies focus on weight loss, the link between fewer calories and longevity has been known since the 1950s and proven with extensive laboratory research. According to Dr. Michael Greger in How Not to Age, simple calorie restriction (without malnutrition) is one of the most potent non-pharmaceutical interventions for extending health span and lifespan. For instance, simply reducing food intake can prolong the average lifespan of rats and mice by 50%.

Clearly, one surefire way to eat less is to limit the time frame in which we eat. Enter the wisdom of time-restricted eating.

Time-restricted eating versus intermittent fasting
The terms “intermittent fasting” and “time-restricted eating” are getting conflated, but in reality, they are two distinctly different things. Time-restricted eating is technically defined as going more than 12 hours without eating in 24 hours. Practitioners of this method establish a limited window of time to eat within those 24 hours, such as 12/12 (eating within a 12-hour window), 16/8, 18/6, with some people going as low as 20/4.

Intermittent fasting, on the other hand, is a pattern of not eating at all for 24 hours, which could be a daylong fast once a week, once every five days, or once a month. There are oodles of variations depending on the goal.

Consistent time-restricted eating gives your body time to burn through calories and triggers all sorts of physiological processes of cellular renewal, which significantly benefits overall metabolic health. Along with eating less overall, most longevity experts recommend moderate time restrictions, such as 12 hours to eat your meals and 12 hours to give your body a rest. While some go so far as endorsing an 8/16 window (i.e., 8 hours to eat and 16 to rest), anything less (such as 20/4) may not allow people to consume enough nutrition to be healthy—especially given that our food is much less nutrient-dense than our ancestors.

Then, of course, the question becomes when to start the window of eating. There are different schools of thought on when the first meal should be; some people prefer to skip breakfast, with lunch being their first meal of the day. However, studies suggest that reducing evening eating and shifting the eating window to the morning may have additional metabolic benefits, including decreased cancer risk. For example, a study of older Italians practicing early eating within a 10-hour-a-day window showed 72% lower odds of suffering from cognitive impairment.

Clearly, the adage "Eat breakfast like a king, lunch like a prince, dinner like a pauper" and its sister version, “Eat your breakfast, share your lunch with a friend, and give your dinner to your enemy," are more than just clever sayings, but words to live by!

Luckily for me, my natural window for eating is earlier in the day because if I eat close to bedtime, I just don’t sleep well—my stomach often bothers me the following day, and interestingly, I wake up much hungrier than usual. I’ve loosely established my normal window between 7:00 AM and 3:00 PM unless I’m having a special dinner (like our family’s traditional Saturday pizza night), and on those days, I delay my start to 10:00ish in the morning.

Restricted mindlessness
For me, perhaps as important as the physical benefits of restrictive eating is the mental discipline of simply being more mindful about when, what, and how I eat… essentially restricting mindlessness, which leads to poor decisions in many aspects of life.

I have found that eating within a window has two immediate benefits. First, it encourages me to carefully consider what I eat to ensure that I get enough variety, quality nutrients, and protein. Second, it cultivates mindfulness and increases self-control, which in turn has cascading benefits throughout life. 

The goal is moderation
The bottom line is that our bodies were designed for food in moderation—not the excesses of our current culture. Although my 8-hour window may be on the recommended outer edge of time-restricted eating, it works for me; why not see what works for you? I encourage you to establish a mindset of eating less overall and to try setting a time-restriction goal for yourself…all in our shared quest to live well, age great.

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