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It’s not just what you eat; it’s how much and when you munch.

Did that last workout convince you that you deserve another serving or snack today?  Think again. Researchers find that restricting calories extends animal life and may do more for humans, too.

This conversation can get a little tricky—especially since we all tend to get a little hangry when we miss our favorite meal or snack. Yet decades of cross-disciplinary research and calorie-restriction studies across a variety of species conclusively show that eating less leads to longevity, along with improved quality of energy, cognitive function and life. According to an extensive review of research and literature on the subject by the Division of Geriatrics and Nutritional Science of the Washington University School of Medicine in St. Louis and published in the “Journal of Gastroenterology,” restriction of calories can slow down aging and prolong life span in 60 percent of experimental animals.

The review considered the status of the present-day knowledge of the impact of diet and metabolism and their impacts on aging and life span. While it concluded that more research is needed—especially long-term research on humans—the aging process can be altered without negative effects such as malnutrition or reduced quality of life, and without new interventions or gene manipulation. Here are some concepts that hold promise for most humans who want to feel better and possibly live longer.

Let the hunger gains begin

It seems counterintuitive, especially when we’ve been conditioned to believe that if we don’t eat, our metabolism and our ability to think will be affected. But the opposite has proved to be the case in studies on calorie restriction. Under the care of a health practitioner, following a carefully reduced diet with high nutritional density for an extended period can lead to positive metabolic adaptations. Some markers include reduction in blood pressure and cholesterol levels, and surprisingly an increase of energy and clarity of thinking.

One theory is that hunger initiates a constant stress level that makes us stronger and more resistant to aging. It’s not the mental stress of a tough day but a physiological state that triggers a cascading metabolic effect in the system. Consuming fewer calories can slow metabolism, and over an extended period—for example one to two years—the body adapts and becomes more efficient. Note that we have yet to see benefits of that plan studied in a clinical environment.

The methods of calorie restriction vary. The most effective study was the CALERIE study (Comprehensive Assessment of Long Term Effects of Reducing Intake of Energy) conducted by researchers from Duke University School of Medicine, the National Institute on Aging, and the National Institute of Diabetes and Digestive and Kidney Diseases. The most effective dieters maintained meals but switched to low-calorie, high-satiety food such as vegetables and fibrous fruit that kept them satisfied. The participants lost weight immediately, reducing their body mass by 15 percent in the first year, and in the second year, they experienced health benefits such as a reduction in the risk of cardiovascular disease by 28 percent and in the protein IGF-1, which impacts aging.

Size matters

In the U.S., we’ve supersized everything from our morning cup of joe to giant green salads loaded down with dressing and toppings, buckets of popcorn at the movies and dessert every day. It’s estimated that we’re consuming on average an extra 1,000 to 1,500 calories that are unnecessary to sustain our activity.

So what’s the right serving size? All you really need is a general understanding of an acceptable quantity of food depending on the type of food. Precision Nutrition has a well-researched and well-tested infographic that is easy to remember. And the Mayo Clinic reminds us that a portion is not equal to a serving. Portion is a specific amount of food on your plate or in the meal, while a serving is related to a specific amount of food containing a certain number of calories. This distinction is particularly useful when comparing the satisfaction of eating a portion of green salad compared to a portion of mac and cheese, which may represent many servings. You might still opt for the cup of macaroni instead of a cup of salad, but at least it’s an informed mouthful.

Say no to the midnight snack

There’s a growing body of research into meal timing. We’ve all had the experience of a day of mindfulness, movement and healthy meals derailed by a midnight binge that makes us feel bad—and not just from going to bed on a full stomach.

One of the hottest conversations right now is about intermittent fasting, which addresses when you eat, not necessarily what you eat. It’s a practice that’s often combined with specific nutritional choices, especially high-fat, low-carb meals, and it’s one of the simplest beneficial strategies for calorie restriction. According to a study by the University of Illinois’ Department of Kinesiology and Nutrition, research shows meaningful results in body composition and other health markers.

There are a number of ways to implement intermittent fasting, including daily, weekly and monthly regimens, and they vary in intensity. Generally, they require fasting eight to 12 hours following a meal, allowing your body to burn more fat than possible in a fed state. Intermittent fasting also tends to lead to reduced consumption of calories. Studies report intermittent fasters experience increased energy, reduced risk of chronic disease, longevity, and improved mental and emotional wellness. And there are lifestyle benefits to intermittent fasting, including a simplified schedule and meal production.

A different kind of full

We don’t have to hunt for our food, and if we raise or gather it, it’s most often a choice to have a vegetable garden rather than a necessity. What’s more, we don’t even have to prepare our food, with many tasty, convenient options readily available to most of us. While easy access to food has given most of us free time to spend in other ways, the trade-off has been in food quality—which can in turn impact our health, vitality, and arguably our creativity and productivity, when you factor in losses of both because of poor health.

If we’re fortunate to have access to nutritious and satisfying food, it’s not a physiological sacrifice to eat better-quality food—in smaller quantities than the portions to which we’ve grown accustomed. And there are more ways to be “fed” than by eating: We often substitute food for emotional satisfaction. There are times when a good conversation, a funny movie or a satisfying snuggle just might be the most fulfilling snack to have.

Photo credits: Jenifoto, eszekglasner S, Dipali S, rh2010, Adobe Stock

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