The ED to be discussed today is not the one that medical doctors diagnose and older men fear. When nutritionists use the abbreviation instead of the full phrase, Energy Density, they are not identifying a disease but assessing a food based on its weight, amount, and volume in relationship to its number of calories.

While the use of abbreviation is fairly new, the concept behind it took root about 20 years ago with the publication of The Volumetrics Weight-Control Plan: Feel Full on Fewer Calories (HarperCollins Publishers, 2000) by Barbara Rolls, Ph.D. In the first of her now six related diet books, Rolls introduced a weight-loss theory she calls Volumetrics that — just like an ED assessment — is based simply on weight, amount, and volume of a food in relationship to its number of calories.

A medium-sized, three-inch-diameter apple, for instance, weighs 182 grams, 156 grams of which are water. It also contains 95 calories and 4.4 grams of fiber.

Because of the apple’s amount of weight, water, and fiber in relationship to its total number of calories, it’s seen as a filling food.

If for some reason you decided to eat three for a mid-day snack, finishing the third could be a chore, yet those three medium apples only contain 285 calories despite weighing 546 grams, a weight that is 1.2 times that of a 13.5-ounce bag of plain potato chips.

And you all know how easy it is to mindlessly eat a whole bag of potato chips while you watch one of your favorite television shows. Doing so, however, means you’ve consumed 2025 calories, about 7 times the number in the three aforementioned apples.

In research lead by Rolls prior to the publication of her first book, it was discovered that — while the number of calories you eat each day can vary significantly — the volume and weight of the food stays remarkably similar. As a result, Rolls’ diet books stress replacing “light,” high-calorie foods with “heavy,” low-calorie ones as a way to lose weight without feeling deprived or hungry.

From Rolls’ research, I believe, the term Energy Density emerged.

Today, nutritionists say that an apple has a low ED and potato chips have a high one.

In a recent article explaining ED, “Energy Density May Help Control Hunger and Manage Weight,” published in this month’s edition of the Environmental Nutrition newsletter, Sharon Lehman, MPH, RDN, suggests using the Nutrition Facts panel as a way to determine ED.

She writes: “If the calories per serving is less than the number of grams in the serving size this means [the food] has a low ED and you can enjoy satisfying portions of that food. If the calories per serving is equal to or up to twice the number of grams in the serving size this means [the food] is moderate in ED and you can eat reasonable amounts being mindful of portion size.

“If the calories per serving is more than twice the number of grams in the serving this means [the food] has a high ED and it’s best to limit your portions to a smaller amount.”

Call it ED, call it volumetrics, but the concept as a form of weight control has been recognized time and time again — in one way or another.

In 2017, for instance, a study published in the July-August issue of the Annals of Family Medicine based on research involving almost 10,000 American adults determined a correlation between carrying too much body weight and ingesting too little water. To establish this, the researchers used urine samples taken for the U.S. National Health and Nutrition Examination Survey 2009-2012.

Urine samples accurately determine hydration levels because they assess all water ingested, whether it be through water, other beverages, or water-filled foods, like fruits and vegetables.

Study leader Dr. Tammy Chang, an assistant professor of family medicine at the University of Michigan Medical School, and her associates found inadequate hydration increased the odds of obesity by 50 percent.

Similarly, researchers at the University of Illinois at Urbana-Champaign used data from the U.S. National Health and Nutrition Examination Surveys from 2005-2008 and 2009-2012 to substantiate a bevy of benefits from drinking more water. The results, published in the Journal of Human Nutrition and Dietetics about this time last year, found people who drank one to three cups more water than the daily average not only consumed fewer empty calories (such as those in sugar-sweetened beverages and junk food possessing no nutritional value) but also less total fat, sugar, sodium, and cholesterol.

Additionally, those whose daily water consumption came in at three cups over the average ate, on the average, 204 fewer calories per day.