DIET AND WEIGHT CONTROL
One needs to understand some commonly used terms before discussing weight control. The term normal weight can mean average, desired, or standard. Normalweight is that which is appropriate for the maintenance of good health for aparticular individual at a particular time. The following is a simple method of determining one’s ideal body weight. It is known as the “rule of thumb” method.
· Males assume 106 pounds for the first 5 feet (60 inches) and add 6 pounds for each inch over 60.
· Females assume 100 pounds for the first 5 feet (60 inches) and add 5 pounds for each inch over 60.
· Large-boned individuals of both sexes increase the first sum by 10%.
· Small-boned individuals of both sexes decrease the first sum by 10%.
This method is quick, but one must remember that it is only an estimate.
Overweight can be defined as weight 10% to 20% above average. Obesity can be defined as excessive body fat, with weight 20% above average. Under-weight is weight 10% to 15% below average.
The medical standard used to define obesity is the body mass index (BMI). It is used to determine whether a person is at health risk from excess weight. The BMI is obtained by dividing weight in kilograms by height in meters squared. Fewer health risks are associated with a BMI range of 19 to 25 than with BMI above or below that range. A BMI between 25 and 30 indicates over-weight, whereas a BMI over 30 indicates obesity. Table 16-1 presents a range of BMIs using English units, so one needn’t do the metric conversion.
The distribution of fat is another indicator of possible health problems. Fat in the abdominal cavity (visceral fat) has been shown to be associated with a greater risk for hypertension; coronary heart disease; type 2 diabetes; and certain types of cancer than has fat in the thigh, buttocks, and hip area. A pear-shaped body has a lower risk for disease than does the apple-shaped body. A waist-to-hip ratio also can give an indication of risk. This is determined by dividing the waist measurement by the hip measurement. A ratio greater than 1.0 in men and 0.8 in women indicates risk for the same diseases as given above. There also appears to be an increased risk of metabolic complications for men with a waist circumference of 40 inches and women with a waist circumference of 35 inches, according to the American Heart Association.
Body weight is composed of fluids, organs, fat, muscle, and bones, so large variation exists among people. In addition to height, one needs to consider age, physical condition, heredity, gender, and general frame size (small, medium, or large) in determining desired weight. For example, a 6-foot 2-inch man with a 44-inch chest, 36-inch-long arms, and 812⁄-inch wrists will weigh more than a 6-foot 2-inch man with a 40-inch chest, 35-inch-long arms, and 712⁄-inch wrists because he has more body tissue. Table 16-2 gives lists of acceptable weights according to age, sex, and height for adults that reflect realistic weight goals.
Some people can weigh more than is indicated on Table 16-2 and still be in good physical condition. Professional football players, because of the amount of lean muscle mass they develop, are examples. However, when they retire and reduce their physical activity, that same muscle can change to fat. If their weights remain the same, they then will be considered overfat because the proportion of fat will have become too high. Some can weigh what Table 16-2 indicates they should weigh and yet be overfat because too great a percentage of the weight is made up of fat.
Body fat is measured with a caliper. Using a caliper correctly requires practice and skill. Because the fat under the skin on the stomach and on the upper arm is representative of the percentage of overall body fat, it is usually measured when knowledge of the percentage of body fat is required. If it is more than 11⁄2 inches, one is considered overweight. If it is under 1⁄2 inch, one is considered underweight (Figure 16-1).
A moderate amount of fat is a necessary component of the body. It protects organs from injury and acts as insulation. The final determination of desirable weight depends on common sense.