Page 174 - Nutrition Essentials for Nursing Practice

162 U N I T 1 Principles of Nutrition

EVALUATING WEIGHT STATUS

From a health perspective, “healthy” or “desirable” weight is that which is statistically cor-
related to good health. But the relationship between body weight and good health is more
complicated than simply the number on the scale. The amount of body fat a person has and
where a person’s weight is distributed also influence health risks, as does the presence of
certain diseases or conditions, such as type 2 diabetes and cardiovascular disease. Table 7.4
summarizes the standards for evaluating ideal body weight, body mass index, and waist cir-
cumference. These values are relatively arbitrary because risk exists on a continuum without
absolute cutoffs.

Ideal Body Weight

Ideal Body Weight: The Hamwi method is a quick and easy way to compute “ideal” body weight (IBW) based
the formula given here on an adult’s height and gender. The formula is as follows:
is a universally used
standard in clinical For women: Allow 100 pounds for the first 5 ft of height
practice to quickly esti- Add 5 pounds for each additional inch of height
mate a person’s reason-
able weight based on For men: Allow 106 pounds for the first 5 ft of height
height, even though this Add 6 pounds for each additional inch of height.
and all other methods
are not absolute. Using this formula, a 5 ft 6 in tall women would have an “ideal” weight of 130 pounds
and a man of the same height would have an “ideal” weight of 142 pounds. IBW can
be adjusted upward or downward by 10% based on estimation of a person’s frame size.
Likewise, for people who are less than 5 ft tall, 2½ pounds are subtracted for each inch
under 5 ft. Although this formula is simple to use, it does not take into account body com-
position or distribution of body fat, both of which impact health risk.

Body Mass Index

In the clinical setting, body mass index (BMI) has replaced traditional height–weight cal-
culations of “ideal” or “desirable” body weight. In 2003, the U.S. Preventive Services
Task Force (USPSTF) concluded that BMI is an acceptable measure for identifying adults

Table 7.4 Evaluating Weight Interpretation
Standard
Percentage of “ideal” body weight Յ69% severe malnutrition
(% IBW) 70%–79% moderate malnutrition
80%–89% mild malnutrition
Body mass index (BMI) 90%–110% within normal range
110%–119% overweight
Ն120% obese
Ն200% morbidly obese

Յ18.5 may ↑ health risk
18.5–24.9 healthy weight
25–29.9 overweight
30–34.9 obesity class 1
35–39.9 obesity class 2
Ն40 obesity class 3