9.5: Healthy Eating

Dietary advice to lower risk of heart disease and cancer are part of the dietary recommendations for a healthy diet, discussed in Chapter 18. A healthy diet includes eating a lot of vegetables and fruits—one of the strongest and most persistent links to less cancer and heart disease.

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Lycopene gives tomatoes a red color and is linked to a lower risk of prostate cancer. Guys who can’t stay away from fries, can at least drown them in ketchup!

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Since fat has been a focus of this chapter and the previous one, let’s look at lowering fat in the diet. By lowering fat intake, one tends to follow other dietary advice as well. A diet lower in fat tends to be higher in plant foods and fiber, and lower in saturated fat, salt, and calories.

Because fat is such a concentrated source of calories, a lower-fat diet helps prevent obesity. Obesity, as we have seen, tends to raise blood pressure and lower HDL-cholesterol, thereby increasing the risk of atherosclerosis. Obesity also raises the risk of diabetes and certain cancers.

Fat Content as a Percent of Total Calories

It’s recommended that 20-35% of the calories in our diet come from fat (see Fig. 9-8). Such advice is too precise to be of practical use to the ordinary consumer—most consumers don’t know whether their fat intake is 25, 30, or 40% of their energy intake. Practically speaking, this recommendation is best followed by knowing how the “% of calories from fat” calculation is made, and using these values as a gauge in making food choices.

Figure 9-8: Recommended fat intake as a percent of total calories.

Comparisons are easiest when fat content is expressed as a percent of total calories rather than as a percent of total weight. When the fat content is expressed as percent of total weight, comparisons are distorted by the amount of water in the food.

For example, fat from dairy products is a major source of saturated fat in our diet. Whole milk contains 3.5% total fat by weight, lower-fat milk is 1–2% fat, and fat-free milk is almost fat-free. It’s not readily apparent that switching from whole milk to lower-fat milk would make much difference in total fat (and saturated fat). Milk, however, is mainly water, so its fat content, by weight, is low and misleading.

To calculate the percent of calories from fat, only two numbers are needed—the grams of fat (or the calories from fat) and the total calories in the food, numbers which are found on food labels and in food composition tables.

About 50% of the calories in whole milk comes from fat, while it’s 35% of the calories in reduced-fat (2%) milk, 15% of the calories in lowfat (1%) milk, and 5% of the calories in non-fat milk. Looking at fat content this way, the advice to switch from whole milk to lower-fat milk is more convincing.

In another example, consider the meaning of 80% fat-free on the label on a package of frankfurters. One wonders if 80% fat-free means that 80% of the fat was taken out of this particular brand of frankfurters, making them low in fat. Looking more carefully at the label, one finds that a frankfurter of 100 calories has 8 grams of fat. Since each gram of fat represents 9 calories, 72 (9 x 8) of the 100 calories (72%) comes from fat:

8 gm fat x 9 calories/gram = 72 calories from fat (72 calories from fat ÷ 100 total calories) x 100 = 72% of total calories from fat

The label is misleading. But it’s technically correct because the percentage of fat was calculated as a percentage of total weight, and over half of the frankfurter is water. The label says that each frankfurter weighs 45 gm and contains 8 gm of fat. This means, that by weight, the frankfurter is 18% fat [(8 gm fat/45 gm total weight) x 100 = 18% fat by weight]. The other 82% of the frankfurter is fat free! It would be more to the point to state, “More than 70% of the calories come from fat,” but this, of course, would be disastrous for sales.

U.S. government standards allow a maximum of 30% fat (by weight) in frankfurters. If there is less fat than this, one can expect this to be emphasized on the label. A label stating 33% less fat, for instance, means that the frankfurters contain 20% fat by weight instead of the allowed 30%.

Going back to the example of switching to lower fat milk, the switch also helps in the Dietary Guidelines to limit saturated fat intake to less than 10% of total calories. 1 cup of whole milk has 30% of its calories from saturated fat; reduced-fat milk (2% fat) has 22%; low-fat (1%) has 17%, and fat-free milk has 5% of it’s calories from saturated fat.

As a final note, keep in mind that there aren’t any forbidden foods in a healthy diet. The point is to eat smaller amounts of foods rich in saturated fat (and foods high in calories and added sugar) or less frequently.