10 Things You Don't Know about Calories

Calories get a bad rap. We blame them for everything -- from making us feel guilty about enjoying a hot fudge sundae with extra nuts to the way our jeans fit (or don't fit, as the case may be).

Yet, demonizing calories is like bad-mouthing oxygen: It's impossible to survive very long without either one. "Calories fuel the body. We need them, just as we should enjoy the foods that provide them," says John Foreyt, Ph.D., director of the Nutrition Research Center at Baylor College of Medicine in Houston and an expert on weight management. "There's nothing bad or magical about calories, it's just that body weight comes down to a simple equation of calories in (from food) versus calories out (as physical activity)."

Here's the real skinny -- answers from the experts to 10 of the most frequently asked questions about calories, and what you really need to know to lose weight.

1. What is a calorie?

"Just like a quart is a measurement of volume and an inch is a measurement of length, a calorie is a measurement or unit of energy," explains dieting-researcher Kelly Brownell, Ph.D., a professor of psychology at Yale University in New Haven, Conn., and author of The LEARN Program for Weight Management (American Health Publishing Co., 2004). "The number of calories in the foods you eat is a measure of the number of energy units that food supplies." Those energy units are used by the body to fuel physical activity as well as all metabolic processes, from maintaining your heartbeat and growing hair to healing a scraped knee and building muscle.

Only four components of food supply calories: protein and carbohydrates (4 calories per gram), alcohol (7 calories per gram) and fat (9 calories per gram). Vitamins, minerals, phytochemicals, fiber and water do not supply calories.

2. How do I calculate how many calories I should cut to lose weight?

First, you need to know how many calories you're currently consuming. You can figure that out by keeping a food journal: tracking calories for everything you eat during a period including at least two weekdays and one weekend day (since people tend to eat differently on weekends). Figure out the calorie count for each food item (see question 3), then tally the total calories and divide by the number of days you tracked your intake to find your daily average.

Or you can roughly estimate your caloric intake by using this formula: If you are age 30 or under, multiply your weight by 6.7 and add 487; women who are 31-60 should multiply their weight by 4 and add 829. Then, multiply the total by 1.3 if you're sedentary (don't work out at all), 1.5 if you're slightly active (work out three to four times a week for one hour), 1.6 if you're moderately active (work out four to five times a week for one hour) or 1.9 if you're very active (work out almost every day for one hour).

Once you know about how many calories you consume per day, try Foreyt's 100/100 plan: "To lose a couple of pounds a month, cut 100 calories from your daily diet and add 100 calories in exercise. This is as easy as eliminating the pat of butter on a slice of toast and walking 20 minutes every day," he notes.

3. How do I figure out the calories in fruits, vegetables and other foods without a nutrition label?

There are dozens of calorie-counting books on the market. Check out Corinne Netzer's The Complete Book of Food Counts, 6th Edition (Dell Publishing, 2003). You also can get similar information for free on the Web. One of our favorite sites is the U.S. Department of Agriculture's online nutrient database at www.nal.usda.gov/fnic/foodcomp/search/.

Use these tools diligently to keep track, and in just a few weeks you'll be able to gauge how many calories are in the portions you typically eat. It's then simply a matter of cutting down on those portions to lose weight.

4. What is the lowest, yet still safe, calorie level I can drop to when I'm trying to lose weight?

"Women should not consume less than 1,200 calories a day," Brownell cautions. In fact, a diet below 1,000 calories a day (called a very low-calorie diet or VLCD) increases your risk for gallstones and heart problems and should be followed only by obese people under a doctor's supervision. While you can drop to 1,200 calories per day and survive, doing so is not a smart idea. Going for a bare-minimum caloric intake may yield quick results, but it also can leave you listless and unable to exercise (key to keeping the pounds off), and may lead to muscle loss and a slowing of your metabolism. Even if you're careful about what you eat, a daily intake of 1,200 calories can shortchange you on important nutrients such as calcium and folate.

Your best bet for success: a moderate calorie cut such as the one Foreyt recommends. That way you'll stay healthy and still have energy for an active lifestyle.

5. Are calories from fat more fattening than calories from carbohydrates and protein?

Yes. "Dietary fat is more readily stored as body fat, because the body must work harder to convert carbohydrates and protein to [body] fat, while dietary fat can be stored as is. That increased work equates to a slight loss of calories," says Robert H. Eckel, M.D., a professor of medicine at the University of Colorado Health Sciences Center in Denver and chairman of the American Heart Association's Council on Nutrition, Physical Activity and Metabolism. When a 100-calorie pat of butter enters your system, your body burns 3 percent of its calories in order to turn it into body fat. But your system uses 23 percent of the calories in carbs and protein to convert them into fat for storage. That said, there is no evidence that dietary fat is stored in any greater amount as body fat than carbs or protein if you are balancing calories in with calories out. Overeating is still the problem -- it's just that it's much easier to overeat fatty foods since they are such concentrated sources of calories.

But be sure not to cut out all fat. A little bit is necessary for body functions, such as vitamin absorption. And monounsaturated fats -- olive oil, nuts, avocados -- have been found to be beneficial for heart health.

6. Do I cut calories or fat to lose weight?

Cut both for best results. "It is a lot easier to restrict calories when you cut fat, while cutting fat aids in weight loss only if it is accompanied by a drop in calories," Brownell explains. The National Weight Control Registry -- an ongoing project at the University of Pittsburgh and the University of Colorado -- found that dieters who maintained a 30-pound or more weight loss for more than one year were successful in part by limiting their calories to about 1,300 a day and keeping fat to about 24 percent of calories.

7. Do calories from saturated fat take longer to burn than calories from unsaturated fats?

Probably not. A handful of studies, mostly on animals, found that the monounsaturated fats in nuts and olives might burn a little faster than saturated fats. "All fats are metabolized differently, but the differences are so slight that switching from one fat to another has no practical use for weight loss," Foreyt says. Of course, the fats from most plants and fish are heart-healthy, so that benefit alone is good reason to switch from filet mignon and butter to fillet of sole and olive oil.

8. Are "empty" and "hidden" calories the same thing?

No. Empty calories describes foods that offer little or no nutritional value. For example, for 112 calories, an 8-ounce glass of fresh-squeezed orange juice offers potassium and supplies 100 percent of your daily need for vitamin C, while the same amount of orange soda has 120 calories and is completely devoid of nutrients. The soda delivers empty calories; the OJ does not. In general, the more a food is processed, the lower its number of vitamins, minerals, fiber and cancer-fighting agents known as phytochemicals, and the higher its content of fat, sugar and empty calories.

In contrast, hidden calories can be found in all types of foods. These are the calories that sneak into your diet quietly, such as from the butter added to vegetables in a restaurant kitchen. "If you eat away from home, you're in for trouble, because you don't know how many hidden calories from fat have been added to your meal," Foreyt warns.

The easiest way to avoid hidden calories is to ask about ingredients whenever someone else has prepared your meal and to request that food you're served at restaurants be steamed, baked or broiled dry. When purchasing packaged foods, always check the nutrition label. That seemingly harmless bran muffin could harbor several grams of fat, upping the calorie content significantly.

9. Do no-calorie foods aid in weight loss?

Theoretically, yes. Switch your daily cola to diet cola and you'll save about 160 calories per 12-ounce can, which should lead to about a 17-pound weight loss over the course of a year. However, scientists have learned that when people consume lowfat, sugar-reduced, low-calorie or calorie-free foods, they typically compensate by eating more of something else later. A Pennsylvania State University study of women found that those who were told they were snacking on reduced-fat yogurt ate more food at their midday meal than did women told the yogurt was full-fat, regardless of the actual fat content of the snack.

To make no- and low-calorie foods work to your advantage, use them in combination with tried-and-true habits for permanent weight loss, such as reducing portion sizes, getting at least 25 grams of fiber a day, eating lots of fruits and vegetables and exercising five times a week.

10. Do calories eaten at night act differently from those eaten during the day?

Not really. "Eat a huge dinner or snack uncontrollably in the evening and there might be a slight fat-storing effect compared with eating a big breakfast followed by a physically active day," Foreyt says. "But the effect is so insignificant that it won't have any noticeable influence on your weight." However, for most of us, dinner typically is the biggest meal of the day, supplying almost half of a person's daily caloric intake, and that's not even counting a late-night snack of ice cream or chips. Bigger portions and excess calories at any time of the day will pack on the pounds. Significant research shows that eating a nutritious, low-calorie breakfast -- for example, a bowl of whole-grain cereal topped with fruit and nonfat milk -- makes it easier to manage your weight. That's not because of any difference in how the calories are burned, but because you're less likely to overeat later in the day if you start off with a healthful meal.