Concentrating on Calories

Obesity has evolved into a major health concern in our society, says James Painter ([email protected]), Chairperson, School of Family and Consumer Sciences, Eastern Illinois University, Charleston, Ill.

“It’s not a mystery how this happened,” he says. “We have lost track of what we eat, and we eat too much.”

Since the mid-1970s, the prevalence of overweight and obesity has increased sharply for both adults and children. Data from two U.S. Dept. of Health and Human Services’ Centers for Disease Control and Prevention National Health and Nutrition Examination Survey surveys show that among adults age 20–74 years the prevalence of obesity increased from 15% (in the 1976–80 survey) to 32.9% (in the 2003–04 survey) (HHS, 2004a, 2004b).

The surveys also show increases in overweight among children and teens. For children age 2–5 years, the prevalence of overweight increased from 5% to 13.9%; for those age 6–11 years, the prevalence increased from 6.5% to 18.8%; and for those age 12–19 years, the prevalence increased from 5% to 17.4%.

Although one of the national health objectives for the year 2010 is to reduce the prevalence of obesity among adults to less than 15%, current data from CDC indicate that the situation is worsening rather than improving.

Food manufacturers and the entire food industry should share the responsibility for weight control, asserts Painter. “Controlling portion size to controlling Calories is a key means by which industry can have a positive impact,” he advises.

Return to Nutrition 101 class and you’ll remember that the “Calories” mentioned on a food package are actually kilocalories (kcal), or 1,000 calories, Painter says. In the lab, a calorie is the amount of energy needed to raise the temperature of 1 g of water 1°C.

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“The original method used to determine the number of kcal in a given food directly measured the energy it produced,” Painter relates. “The food was placed in a sealed container surrounded by water, an apparatus known as a bomb calorimeter. The food was completely burned, and the resulting rise in water temperature was measured. This method is not frequently used today.”

Currently, the Calories (kcal) listed on food packages are calculated using a food composition table, according to the Nutrition Labeling and Education Act of 1990 (NLEA). The National Data Lab (NDL) states that most of the Calorie values listed in the U.S. Dept. of Agriculture tables and industry food tables are based on an indirect Calorie estimation made by using the Atwater system.

“In this system, the total Calorie value is calculated by adding the Calories provided by the energy-containing nutrients, specifically protein, carbohydrates, fat, and alcohol,” Painter says. “Because carbohydrates contain some fiber that is not digested and utilized by the body, the fiber component is usually subtracted from the total carbohydrate before calculating the Calories.”

A complete discussion of this subject and the Calories contained in more than 6,000 foods can be found on the NDL Web site at www.nal.usda.gov/fnic/foodcomp.

Another online tool that allows the user to total the Calorie content of limitless numbers of foods is the Nutrition Analysis Tool (www.nat.uiuc.edu), which Painter developed in 1996.

Laboratory Analysis
Private laboratories can assist in Calorie content analysis, especially when a specialized chemical analysis is warranted, such as when a product is so new that no precedents exist for measuring its components.

ABC Research Corp. (phone 352-372-0436,www.abcr.com), Gainesville, Fla., is one such lab.

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“We determine Calories by first measuring the moisture, protein, fat, and ash content,” says Kathy Barry ([email protected]), ABC’s Food Chemistry Director.

ABC uses the formula 100 – (moisture + protein + fat + ash) = carbohydrates. Calories are then calculated using the formula 4 × protein + 4 × carbohydrates + 9 × fat = Calories/100 g.

“Our clients include food manufacturers, restaurants, and fast-food establishments that typically want a full nutrition panel,” Barry says. “We run about 500 such tests per year.”

There are actually five ways to calculate Calories for a label, three of the most popular being the 4-4-9 formula, 4-4-9 minus fiber, and Atwater factors, says Layne Westover (layne@esha. com), Vice President of Marketing and Business Development, ESHA Research, Inc., Salem, Ore. (phone 800-659-3742 or 503-585-6242, www.esha.com). “Manufacturers usually use 4-4-9 or 4-4-9 minus fiber, and USDA uses Atwater factors,” he says.

The 4-4-9 method, which produces average conversion-factor values, uses the following formula:
• g of protein × 4 kcal/g = kcal from protein

• g of carbohydrate × 4 kcal/g = kcal from carbohydrates

• g of fat × 9 kcal/g = kcal from fat The 4-4-9 minus fiber method uses the following formula:

• g of protein × 4 kcal/g = kcal from protein

• (g of carbohydrate – g of fiber) × 4 kcal/g = kcal from carbohydrates

• g of fat × 9 kcal/g = kcal from fat

“Atwater Factors tend to be more precise,” Westover says. “Different foods have differing caloric contributions per gram. For example, 1 g of fat from one food may yield 8.4 kcal, while 1 g of fat from another food may yield 9.37 kcal. For fat, the values ranged very near 9 kcal, but it is not exactly 9 kcal. The same concept holds true with a gram of protein or carbohydrate. Generally, you’ll find Atwater Factors result in slightly less total Calories than when you approximate using 4-4-9.

“Finally, when displaying Calories on a nutrition facts panel, the value is rounded according to NLEA rounding rules, further skewing the discrepancy,” Westover adds.

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Software Tools
To assure accuracy when determining the amounts of Calories and other nutrients, it’s a good practice to compare any lab analyses with nutrition analysis software,Westover says. “It is critical to have quality,/accurate data. It is equally important to use current, reliable software.”

Genesis R&D SQL—the newest generation of ESHA product formulation and labeling software—offers camera-ready NLEA-compliant labels, as well as ingredient statements and appropriate nutrient content claims.

ESHA’s nutrient database consists of more than 27,000 foods and ingredients. “The information is collected from more than 3,000 sources, including USDA and brand-name and fast-food suppliers,” Westover says. “The Canadian Nutrient File is also available, offering an additional 5,000 foods.”

The ESHA database includes whole foods, raw materials, chemicals and additives, combination foods, brand-name items, fast foods, and baby foods. “Users can also add an unlimited number of their own ingredients,” Westover adds.

“The Calorie remains the single most requested piece of nutrition information,” Westover asserts. “The science of Calorie analysis has not significantly changed in the last half century. What has changed is the level of interest and the application of that information. When we license data for nutrition and recipe analysis Web sites, Calories are the number-one component our clients request. Health issues, including obesity, diabetes, high blood pressure, and other related disease states, are driving the demand for Calorie information.”

As consumers demand that restaurants make available the nutritional information of foods, we will likely see additions to the NLEA or a new regulation that will require restaurants to provide nutritional data such as calories, fat, sodium, and sugar for menu items targeted to those consumers battling obesity, high blood pressure, and diabetes, suggests George Baker (georgeb@abcr. com), Chief Executive Officer, ABC Research Corp. “Calories are likely the most important factor in maintaining a healthy weight,” he says. “According to the National Institutes of Health, genetics and other factors affect how your body uses the calories you consume. Still, the only way to gain weight is by taking in more calories than you burn.”

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In light of increasing numbers of obesity cases, it’s no surprise that efforts to provide information about the caloric content of food may not be embraced or appreciated by consumers, says Jeanne Goldberg ([email protected]), Director, Graduate Program in Nutrition Communication, Friedman School of Nutrition Science and Policy, Tufts University, Boston, Mass. Goldberg served as principal investigator on the research that led to the selection of the Food Guide Pyramid by USDA and HHS in 1992.

“Yes, Calories are important and it’s important to know how many Calories are in a serving, but what does a serving look like in a consumer’s eyes?” Goldberg wonders.

Even with Calories-per-serving amounts listed on the package, consumers may not look at the number of servings on the package, Goldberg points out, even with that information on the label. “That’s because consumers may not understand the label and they may have a preconceived notion of what size serving they want,” she explains. “Nonetheless, it’s important for food manufacturers and restaurants to disclose the number of Calories per serving.”

In a restaurant, Calories are typically controlled, and especially in some chain restaurants portions tend to be more precise, Goldberg says. “But even in chain restaurants, there can be flexibility. For example, one employee may add more or less filling to a fajita, and that, of course, affects how closely the caloric information relates to the Calories in the actual serving.”

As a result, it’s necessary to stand back and look at the different servings, especially if a restaurant is posting the caloric content of its menu items, Goldberg advises. “Increased possibilities for human involvement in the serving process means all bets are off as to actual Calorie count in the portions,” she says. Unless someone weighs or premeasures portions, she says, the Calories on the label and what is actually served may be significantly different.”

Goldberg is quick to point out that even when caloric content of foods or servings is made available to consumers, they may not be interested or care about it or want to be hounded by it.

“Taste is absolutely the number-one driver in food choices,” she emphasizes. “Cost and convenience tend to be second and third. Health runs a solid fourth.”

by Linda L. Leake,
Contributing Editor,
Food Safety Consultant, Wilmington, N.C.
[email protected]

References