Q. Is regular whole milk really only about 3 percent fat?

A. Yes. The fat percentage figures refer to how much of the milk's total weight comes from fat. Whole milk is about 88 percent water, 3.25 percent protein and 5.25 percent lactose (milk sugar), according to Christine Bruhn, a professor of food science at the University of California-Davis. It's about 3.25 percent fat on average and therefore about 96.75 percent fat-free. However, that doesn't mean there aren't tremendous calorie differences among types of milk.

• Whole milk (1 cup): 150 calories, 70 calories from fat (about 47 percent of the calories are from fat).
• Two-percent milk (1 cup): 120 to 130 calories, 45 calories from fat (about 35 percent of the calories are from fat).
• One percent (low-fat) milk (1 cup): 90 to 100 calories, 20 calories from fat (about 20 percent of the calories are from fat).
• Skim (nonfat) milk (1 cup): 80 calories, 0 calories from fat.

"Choosing low-fat or nonfat milk offers a pretty significant calorie savings as well as a reduction in unhealthy, saturated fat," says Gail Woodward-Lopez, the associate director of the Center for Weight and Health at the University of California-Berkeley. Also, if you find skim milk a bit "weak," try mixing it with 2 percent milk until you get used to it, then keep adding less and less of the 2 percent.

Q.Which has more calories: unhealthy saturated fat or "heart-healthy" monounsaturated and polyunsaturated fats?

A. All fats, gram for gram, have virtually the same number of calories. "Fat (whether it's saturated or not) has 9 calories per gram," says Alice H. Lichtenstein, a nutrition professor at Tufts University. Nevertheless, saturated fat has been linked to high cholesterol and should be limited in your diet, whereas unsaturated fats have heart-healthy properties (but still have calories). Saturated fats, such as butter, are typically solid at room temperature, whereas unsaturated fats, like oil, are liquid.

Q. What is the most common nutrient deficiency in America?

A. According to Dr. Mary Cushman, associate professor of medicine and pathology at the University of Vermont, iron deficiency is the most common. Those at highest risk include infants, teenage girls, pregnant women and the elderly. Iron is an essential mineral necessary for the formation of hemoglobin, which carries oxygen in the blood, and myoglobin, which carries oxygen in muscle tissue.

In general, dietary iron is absorbed poorly. Animal sources, including poultry, red meat and fish, seem to be the best for absorption of iron. Plant sources include dried fruits, leafy green vegetables, nuts, legumes and whole-grain products. Be sure to ask a physician about your requirements, because too much iron is not good, either.

Q. Which is the best oil?

A. They're all pretty much equal in terms of weight control — meaning that all oil has about 120 calories per tablespoon. Yes, regular vegetable oil has the same number of calories as olive oil. Just because an oil is heart-healthy doesn't mean it's calorie-free. The best oils? "While most of the vegetable oils are pretty low in saturated fat, technically canola and soybean are the best," Lichtenstein says. "They are both high in omega-3 fatty acids, and soybean oil is high in polyunsaturated fat while canola is high in monounsaturated fat — both of which are heart-healthy." Does that mean olive oil isn't good? "Olive oil tastes great and is a very good oil, and it is important to actually enjoy your food," adds Lichtenstein.

Q. Is it true that cooking sprays like Pam and Mazola have no fat at all?

A. No. First of all, to qualify as "fat-free," a food must have less than 0.5 gram of fat per serving. The key words here are "per serving." These claims are based on standardized serving sizes, which can be unrealistic or confusing. And even though Pam has less than 0.5 gram of fat per serving, technically qualifying it for the "fat-free" claim, the Food and Drug Administration thought such an assertion would be misleading for a product that is essentially 100 percent fat (that's right — it's full of fat). The compromise was to allow Pam and other similar products to put the words "for fat-free cooking" on the label.

I'm still a fan — as long as you're careful about how long you're spraying!

Q. If you see the term "No Added Sugars," does that mean the food is a low-calorie or reduced-calorie food?

A. No. The words "no added sugars" and "without added sugars" only mean that no sugar or sugar-containing ingredients (such as fruit juice, applesauce or dried fruit) are added during processing or packing. So don't be fooled — read the nutrition facts and check the calories per serving.

Q. Is it true there's no real benefit to washing meat and poultry?

A. Yes. Believe it or not, washing poultry or meat (with regular water) does not effectively reduce the pathogens that cause food-borne illnesses, says Mark Sobsey, a professor of public health at the University of North Carolina at Chapel Hill. In fact, washing these foods could actually increase your risk of getting sick, because it could easily spread germs on your hands and around the sink, warns Sobsey. The best way to ensure that these foods don't make you sick is to cook them properly. That means heating them to the proper temperature and making sure no red or pink color is visible.