Technically speaking, fat is a whole family of compounds called "lipids." They are often categorized as saturated, monounsaturated, and polyunsaturated. Your "total fat" is all three types added together. On food labels, total fat is usually called just "fat."
Fats are the body's most concentrated source of energy. An ounce of pure fat provides 255 calories; an ounce of pure protein or carbohydrate, only 113.
Besides energy, fat helps to deliver certain nutrients to your body. Among them are linoleic acid, which contributes to healthy skin, blood clotting, good kidney function, and fertility; and vitamins A, D, E, and K, which enter your system more readily when dissolved in fat.
Fats also figure in the manufacture of hormones, cell membranes, nerve coverings, and prostaglandins (substances that control blood pressure and muscle action in internal organs).
The best sources of fat are meats, vegetable oils, dairy products, eggs, nuts, and grains.
Eating too much fat is one of the industrialized world's most common nutrition problems. Excess fat in the diet not only fosters obesity (because fat is rich in calories), but also figures heavily in heart disease, stroke, cancer, and other ailments. That's why, for many years, most nutrition experts have recommended getting no more than 30 percent of your calories from fat. (The latest recommendations are more lenient, however¾see "Your Daily Allowance," below.)
Although rare, it is also possible to eat too little fat. As a minimum calories-from-fat figure, authorities used to suggest about 10 percent¾but in 2002 the Food and Nutrition Board (FNB) raised this significantly. See "Your Daily Allowance," below.
In 2000, the average American got about 34 percent of calories from fat¾down from 37 percent in the early 1970s.)
Your Daily Allowance
In September 2002, the Food and Nutrition Board issued new guidelines for fat intake. Adults, it said, should get between 20 and 35 percent of their calories from fat, while children aged four** to 18 should get between 25 and 35 percent from fat. The Board cited two reasons for raising the minimum: 1) new research shows that extremely low-fat diets cut the amount of HDL or "good" cholesterol in the blood, thereby raising heart-disease risk, and 2) children need more fat during their growing years.
Most experts are quick to point out, however, that 35 percent is a ceiling¾not an ideal. Hence, Diet Power sets your Personal Daily Allowance (PDA) at the number of grams required to make up 25 percent of your PDA of calories.
** But remember that Diet Power is not designed for people under 15.
The FNB has not established a Tolerable Upper Intake Level (UL) for fat. For guidance, see the notes above.
Revising Your Allowance
If your doctor recommends a different intake, you can revise your PDA. See Personal Daily Allowances, Editing Your.
Color Coding of This Nutrient
The fat bar in your personal Nutrient History is:
· blue for "good" if you've logged 50 to 100 percent of your PDA
· red for "bad" if you've logged more than 100 percent of your PDA
· yellow for "caution" if you've logged less than 50 percent of your PDA
· missing if you've logged no fat.
In the nutrient profile of a food or recipe, the fat bar is:
· green for "good" if getting your entire PDA of calories from this item would give you less than 50 percent of your PDA of fat
· magenta for "bad" if getting all your calories from the item would give you more than 150 percent of your PDA of fat
· blue for "neutral" otherwise
· missing if the amount of fat is either zero or unknown.
On pie charts, the fat wedge is always red:
How Complete Are Diet Power's Total-Fat Readings?
Absolutely complete. Of the 11,000 items in the Food Dictionary, none list their fat content as "unknown."
(There will be unknowns, of course, if you've added foods to the dictionary with missing fat figures. But these won't be marked as unknowns. Since fat is one of the four energy nutrients, Diet Power needs a figure in the Fat column in order to calculate a food's calorie content. If you leave a blank or a question mark there, the program automatically changes it to a zero.)
To see whether a particular food has a fat reading, open the Food Dictionary and check the food's nutrient profile. If you find a question mark beside "Fat," it means the amount is unknown. (To see all foods with unknown fat readings, click the dictionary's PowerFoods tab and sort the foods by fat power; then scroll toward the bottom of the list until you see foods with question marks in the "Power Rating" column.)
Total Fat on Food Labels
Almost all food labels are required to report total fat content, in both grams and percent of Daily Value (DV).
The Daily Value for total fat is 65 grams for a person eating 2000 calories a day. At nine calories per gram, this means such a person would be getting a little over 29 percent of his calories from fat¾very near the FNB-recommended ceiling.
Labels must also state how much of the fat is saturated, but they do not have to include breakouts for polyunsaturated and mononsaturated fats.
For more on label regulations, see Labels, Food.