I was born in 1972, but I have a thrifty streak—the unkind might call it cheap—you might expect from someone who grew up during the Depression. And when I make dinner for myself, I have gotten in the habit of mixing my tofu or fish with tons of green beans to stretch out the protein and make it last for several meals, not just one. In addition to saving money, I've been inadvertently practicing the weight-control technique known as energy density reduction, or, more catchily, "Volumetrics."
That's the term Barbara Rolls, professor and Guthrie chair of nutrition at Pennsylvania State University, has coined to describe the method, which is based on a simple principle: People tend to eat the same weight, or amount, of food from day to day. Since some foods are less energy dense—that is, they have fewer calories per gram—than others, if you fill your plate with more of those foods, you'll be eating fewer calories without actually eating less food. It's a different slant than portion control, the usual rule of thumb for weight control.
U.S. News has written before about the history of Volumetrics. Since then, Rolls's research has shown that cutting energy density is indeed associated with weight loss. Just this summer, her team published a study showing that by cutting the energy density of a pasta entrée served at a day-care facility by adding veggies, kids consumed fewer calories during the meal. (The tendency to eat a consistent volume of food begins very early, Rolls says.) T his week, an independent Japanese study published in Nutrition
supported the Volumetrics principle, finding that women who ate foods containing a lot of water had lower BMIs and waist circumferences than those who did not.
Foods with a lot of water in them are less energy dense than those without, since water has no calories and so dilutes the caloric content of the food. (Other variables you can tinker with: fiber and fat. Foods with more of the former are less energy dense, and those with more of the latter have more calories per gram.) Water is easy to control; swapping fruits and vegetables (which are 80 to 95 percent water, says Rolls), soups (also up to 95 percent water), hot cereal (85 percent), or low-fat yogurt (75 percent) for calorie-dense foods like cheese (35 percent water), bread (up to 40 percent) and saltines (3 percent) can make a huge difference in the calorie content of your typical meal. Oh, and in case you were thinking you could get the same effect by swigging a huge glass of water with your Big Mac: nice try. The Japanese study reinforces what Rolls has found before: that the water needs to be in the food to make a difference.
It's not always easy to size up a food for it energy density. (The saltines figure above floored me—who knew?) If you're reading labels, one rule of thumb is to give yourself a green light for anything that has fewer calories than grams per serving (say, 35 calories for a 40-gram serving). Similarly, be cautious about overdoing anything with more calories than grams per serving, and really control the amount of a food whose calories add up to more than twice the number of grams per serving.
A book by Rolls, The Volumetrics Eating Plan, includes recipes modified to cut energy density. I'm planning on trying some of them; I've included some of her meal fixes below.
- Pancakes: Cut the oil and butter, switch to whole-wheat flour, use raspberry sauce instead of syrup, then add more fresh fruit on top.
- Frittata: Reduce the amount of egg yolks and sub egg whites. Use low-fat cheese. Load it up with vegetables instead of meat.
- Party platter: Instead of chips and dip, offer vegetables and low-fat dips, like hummus and salsa. Or use air-popped popcorn.
- Asian spring rolls: Use a thinner rice-paper wrapper, and serve fresh instead of fried. Load it with veggies.
- Stuffed peppers: Rather than filling them with sausage, use bulgur and vegetables—and less oil.
- Strawberry milkshake: Swap nonfat, sugar-free yogurt for whole milk and ice cream, use fruit, and add ice to bulk it up.
- Chicken salad sandwich: Use whole-wheat bread instead of a croissant and lower-fat mayo instead of the regular kind. Add grapes.
- Greek salad: Use less oil and load up with veggies. Use nonfat feta cheese.
- Pasta with red sauce: Puree cauliflower and broccoli to mix into the sauce, and add whole vegetables as well.
- Strawberry trifle with lemon cream: Use yogurt cheese and reduced-fat cream cheese. Add extra fruit and use fewer cookies.