What's Your Nutrition IQ?

Getting the facts about food can help you lose weight.

By Kathleen Zelman, MPH, RD, LD
WebMD Weight Loss Clinic - Expert Column

The more you know about nutrition, the more you can eat! So trust me when I tell you: Nutrition knowledge is power.

To help you test your nutrition know-how, I devised this true/false quiz. So sit back, relax, and give it a shot: It's fun, and you may learn a thing or two along the way.

1. True or false? To lose 1 pound of body weight, you must burn 3,500 calories.

True. To burn a pound of fat and not water or muscle weight (we need to preserve every ounce of muscle!), you must create a deficit of 3,500 calories. You can do this by reducing the number of calories you eat, burning more calories through physical activity, or both. Studies show that the most effective strategy is combining diet and exercise to create a 500-calorie daily deficit. That adds up to 3,500 calories -- and a 1-pound loss -- per week. Faster weight loss is usually ineffective over the long run, as pounds lost quickly often get a round-trip ticket back. Slow and steady wins this race.

2. True or false? Carbs, proteins, and fat all have about the same amount of calories.

False. Carbohydrate and protein each weigh in at 4 calories per gram, while fat has 9 calories per gram, and alcohol has 7 calories per gram. Ounce for ounce, foods that contain mostly fat are more than twice as calorie-dense as carbs or protein. For good health, you need to consume all the major nutrients: carbs, fat, and protein. Each has essential functions. Carbs and protein should account for about two-thirds of your daily intake; the remaining third should come from fats.

Carbohydrates are not as evil as some would have you believe. In fact, carbs are your body's preferred form of fuel. They should be the mainstay of your eating plan, accounting for up to half of your calories. Choose "smart" carbs such as fresh fruits, vegetables, whole grains, beans, and peas. Simple refined carbohydrates, such as white bread, soda, and sugars, are the carbs that should be restricted.

3. True or false? Excess calories from fat are more easily stored as body fat than other types of calories.

True. Extra dietary fat is easily stored as body fat. Excess proteins and carbs require more work to be converted for storage. Only 3% of the calories from fat are used up in the process of storage, while 23% of the calories in carbs and protein are used in this process. And people tend to overeat fat because high-fat foods tend to pack lots of calories into a relatively small package (such as cookies).

But it's important to remember that an eating plan that stays within your calorie needs -- regardless of the combination of fats, carbs, and protein -- will not result in weight gain. The most important factor is to balance calories consumed with calories burned, so that you burn fat instead of storing it.

4. True or false? "Empty calories" refers to foods that are "free," or have virtually no calories.

False. Empty-calorie foods are those that offer little nutritional value, but lots of calories. Most empty-calorie foods have few vitamins, minerals, or fiber, but are high in calories, fat, and/or sugar. To avoid them, check the Nutrition Facts panel on food labels and choose foods that offer at least 20% of the recommended Daily Value of a few vitamins and minerals (except sodium -- we all get plenty of that mineral).

5. True or false? Calories eaten at night turn to fat more easily than those eaten during the day.

False. Whether you lose or gain weight comes down to this formula: Calories in - Calories Out = Weight Loss (or Gain). "Calories in" come from the food and beverages you consume. "Calories out" include those burned by physical activity; those your body burns even when at rest, by functions such as breathing; and the "thermic activity" of food (the number of calories it takes to digest and absorb food).

Many experts recommend consuming all your calories before 8 p.m. because most of us are sedentary after that hour and less likely to burn extra calories. And it is a good habit to eat most of your meals during the more active phases of the day. But the bottom line is that it's the total number of calories you consume -- regardless of the time of day -- that determines whether you gain or lose weight.

6. True or false? Meats described as "lean" are healthier choices.

True. According to government definitions, "lean" refers to cuts of meat (including poultry and game) with less than 10 grams of total fat, 4.5 grams of saturated fat, and 95 milligrams of cholesterol per 3.5-ounce cooked serving. The only exception is for ground beef labeled as 80%-95% lean. Ground beef that is 95% lean has 5% fat by weight -- which is equivalent to 6.4 grams of total fat per serving, and still qualifies as lean. But ground beef that contains more than 5% fat by weight is too high in fat to be considered lean.