The case of the missing calories - calculating calorie count - Answering Machine

Vegetarian Times, Oct, 1996 by Randi Rose

What is the methodology for determining the total number of calories? As a health educator, I know to calculate calorie content one must first know how many grams of fat, carbohydrates and protein are in the product. I am also aware that fat has 9 calories a gram and protein and carbohydrates each have 4 calories a gram. Knowing this, it should be simple multiplication and addition to determine total caloric content. Yet everywhere I look, the listed calorie total is different from my calculations. Why doesn't my math add up? Please respond because this dilemma is about to drive me batty.

--J. R., Livingston, Texas

Don't go nuts. The reason your calculations don't match those from corporate America is not your math. Rather it is due to the "rounding off" skill taught to elementary school students. When it comes to tallying calorie content based on food label information, so many of the figures have been rounded off-including the fat, protein and carbohydrate amounts --that your calorie total can be significantly different from the official total on the label.

There is a method to labeling madness. Companies follow strict government criteria to reach the values they list on the Nutrition Facts label. The ultimate figures are meant to be reliable guidelines allowing consumers to compare like products with ease. The figures are not meant to be exact. The result: "More often than not, the calorie total will be slightly different from a consumer's calculations," says Virginia Wilkening, M.S., R.D., of the office of food labeling at the U.S. Food and Drug Administration (FDA).

Take, for example, a bag of pretzels. You have 2.5 grams of fat, 32 grams of carbohydrates and 4 grams of protein. If we multiply 2.5 grams of fat by 9; 32 grams of carbohydrates by 4; and 4 grams of protein by 4, we get a total of 166.5 calories. Yet the official calorie count listed on the label is 170.

The FDA rounding rules corporations follow when determining their nutrition breakdowns are:

* FAT MUST BE DECLARED on a food label to the nearest half a gram, if there are fewer than five grams of fat in the product. For products with more than five grams of fat, companies round to the nearest whole number. So a product with 4.6 grams of fat would say 4.5 grams on the label; a product with 5.4 grams of fat would say 5 grams.

Carbohydrates and protein are always rounded to the nearest whole number.

* CALORIES ALSO MUST be listed in specified increments. Ever wonder why most cereals have exactly 110 calories per cup and not, say, 112 or 109? If a product has 50 calories or fewer, the manufacturer must round off to the nearest multiple of five. If a product has more than 50 calories, the manufacturer must round off to the nearest multiple of 10. These unnaturally tidy numbers are meant to clue you in to the fact that they're inexact--of course, consumers don't always catch on. "We required increments so the label wouldn't be read as being more precise than it is," says Wilkening. "We expect things to fall into a bell-shaped curve with an equal number of products rounding up on calories as rounding down."

* THE 9-4-4 NUMBERS that nutrition-savvy consumers can recite with the fluency of the alphabet are also approximations meant for rough calculations. For example, the notion that carbohydrates have four calories per gram is rounded up from 3.6. This explains the label on a can of Coca-Cola Classic. This product has no fat or protein and 39 grams of carbohydrates. Multiplied by 4, the soda appears to have 156 calories, but the label claims 140. Coca-Cola spokesperson George Barkley confirmed that the company reaches the 140 figure by multiplying the carbohydrate grams by 3.6. "Those 16 calories won't make a hill of beans in a diet," explains Kathleen Zelman, R.D., a Marietta, Georgia-based nutritionist and spokesperson for the American Dietetic Association. "People must believe the numbers on a label but accept that there is a margin of error." Protein tends to have 4.1 or 4.2 calories per gram, depending on the source.

If this explanation isn't enough to drive you batty, the following additional guideline may. A separate rule applies to the calorie count on products that contain insoluble fiber. The FDA allows manufacturers to subtract out from the calorie total those that are attributable to insoluble fiber because they pass through the body undigested. Quaker subtracts out insoluble fiber when tallying the calorie content for its oat cereals, according to a spokesperson.

Worried that all these imprecise numbers mean you can't judge a product by its nutrition label? Don't be. Although the math may be confusing, the bottom line is whether or not you can trust the numbers on food labels. A study done last year at St. Luke's-Roosevelt Hospital in New York City evaluated a variety of products sold nationally and found the labels are accurate. In fact, because manufacturers often prefer to print the calorie contents rendered with exact numbers (3.6 multiplied by carbohydrate grams gives a lower number than multiplied by 4), the calorie information provided on a product will be more accurate than home calculations performed based on the 9-4-4 formula.