Anthropometric Surveys

When energy intake is insufficient to meet requirements, energy is derived by metabolizing fat and lean tissues, mainly muscle. Children first stop gaining height/length and then lose weight, whereas adults lose weight. Weight loss is more rapid in children

Figure 3 Dietary energy supply (DES), 1994-1996. (Reproduced with permission from the Food and Agriculture Organization (2000) Undernourishment around the world. Counting the hungry: Latest estimates. In: The State of Food Insecurity in the World. Rome: FAO.)

than in adults because of their higher energy requirements per kilogram body weight, mainly due to a different body composition. Population-level measurements of body weight and height/length in children indirectly assess the adequacy of food intake on the assumption that a low average body weight and height/length compared with a growth reference reflects an inadequate diet. WHO recommends that the following be used to compare undernutrition in children in different areas of the world:

• Underweight is defined as the proportion of children whose weight in relation to their age is below —2 standard deviations (—2 z scores) of the median of the National Center for Health Statistics (NCHS) reference.

• Wasting is the proportion of children whose weight in relation to their height is below —2 z scores of the median of the NCHS reference.

• Stunting is the proportion of children whose height in relation to their age is below —2 z scores of the median of the NCHS reference.

The previous calculations underestimate the true prevalence of undernutrition because a child can be below his or her optimal weight or height/length yet remain above the —2 z score cutoff point. Wasting is often described as acute malnutrition because it reflects relatively recent weight loss, and stunting is described as chronic malnutrition. Growth retardation is often described as protein-energy malnutrition, which is a misnomer because there is increasing evidence that other nutritional deficiencies besides protein-energy, such as zinc, can lead to growth faltering. Severe undernutrition is defined by a weight in relation to height below —3 z scores of the NCHS reference (marasmus) and/or by the presence of nutritional edema (kwashiorkor or marasmus kwashiorkor), and it is associated with a high risk of dying. WHO and UNICEF maintain a global database on the prevalence of undernutrition among children. Stunting is more prevalent than underweight (Table 1) and is often used to monitor long-term trends in undernutrition.

In emergency situations, rapid assessment surveys are often carried out using the mid-upper arm circumference as a proximate indicator of nutritional status in children and, increasingly, adults. This approach is less reliable than methods based on

Table 1 Prevalence of undernutrition by region

UNICEF region

Under-5

Wasting

Weight Loss Resolutions

Weight Loss Resolutions

Are You Tired Of Failed New Year's Weight Loss Resolutions That Leave You Even More Overweight Than Ever Before? Not Anymore Finally Succeed With Your New Years Weight Loss Resolution Once And For All And Get The Body Of Your Dreams.

Get My Free Ebook


Post a comment