Healthy reference population

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Healthy reference population

Description

A healthy reference population, HRP, of zero underweight or overweight is considered as a standard population. The WHO Child Growth Standards on height and body mass are based on large samples in longitudinal (N=1737 children) and cross-sectional studies (N=6669) with similar numbers of girls and boys from Brazil, Ghana, India, Norway, Oman and the USA (1997-2003). Anthropometric studies carried out on adults since the 1960ies are prone to reflect the impact of high-caloric nutrition on allometric relationships, referring us to earlier time points for a HRP. The Committee on Biological Handbooks compiled a large dataset on height and body-mass of healthy males from infancy to old age (CBH dataset, N=17523; Zucker 1962). The original studies were published between 1931 and 1944 and thus apply to a population (USA) before emergence of the fast-food and soft drink epidemic, and with a lifestyle demanding a balanced physical activity without the impact of local war or economic disaster on starvation.

Abbreviation: HRP

Reference: Body mass excess

From BMI to BME

Four allometric phases

The HRP is characterized by three allometric phases in childhood to early adolescence (up to 1.26 m height), and a final phase with an exponent of 2.867 (=1/0.35) >1.26 m, equal in women and men (Fig. 1; green line).

Figure 1: Four phases of the allometric relationship between body mass, M°, and height, H, in the healthy reference population (HRP), and shift of M at body mass excess, BME, indicating underweight (BME = 0.8 and 0.9) or overweight (BME = 1.2) and increasing degrees of obesity (1.4 to 2.0). Compared to the HRP, the body mass index, BMI, assumes a more shallow increase of M° with H, hence a BMI of 20 indicates overweight (1.2M°) at 1.38 m, but underweight (0.9M°) at 1.92 m.

Personalized BMI-cutoffs

Figure 2: Comparison of fixed BMI-cutoffs (dashed horizonal lines at BMI 18.5, 20, 25, 30 and 35) and personalized BMI-cutoffs, BMI_x, as a function of height in the four phases of the allometric relationship. The personalized BMI-cutoffs are related to the reference body mass, M°, of the healthy reference population (HRP), and body mass excess, BME, from 0.8 to 2.0 (the numbers indicate the personalized BMI-cutoff lines).

The fixed BMI-cutoffs at BMI 18.5 kg·m^-2 for underweight, or 25 and 30 kg·m^-2 for overweight and obese, do not support a general categorization from children to adults, for women and men, or different ethnic groups. The BME-concept resolves these limitations, with BME-cutoffs at 0.9 for underweight, or 1.2 and 1.4 for overweight and obese for a large range of ethnic groups including white Caucasians, Black Americans and Asians (Inuit are an exception). Differences in height between Caucasians and Asians explain the limitations of fixes BMI-cutoffs. The BME-concept rationalizes the necessary adjustments in the BMI-cutoffs for Asians, and thus presents personalized BMI-cutoffs (Fig. 2).

References

1. WHO Multicentre Growth Reference Study Group (2006) WHO child growth standards based on length/height, weight and age. Acta Pædiatrica Suppl 450:76-85. - »Bioblast link«
2. WHO Multicentre Growth Reference Study Group (2006) WHO child growth standards: length/height-for-age, weight-for-age, weight-for-length, weight-for-height and body mass index-for-age: Methods and development. Geneva: World Health Organization:312 pp. - »Bioblast link«
3. Zucker TF (1962) Regression of standing and sitting weights on body weight: man. In: Altman PL, Dittmer DS, eds: Growth including reproduction and morphological development. Committee on Biological Handbooks, Fed Amer Soc Exp Biol:336-7. – Anthropometry, H and M°, of the healthy reference population, HRP; based on [3.1-3.5]. - »Bioblast link«
   1. Bayley N, Davis FC (1935) Growth changes in bodily size and proportions during the first three years. Biometrika 27:26-87.
   2. Gray H, Ayres JG (1931) Growth in private school children. Behavior Res Fund Monog, Univ Chicago Press, Chicago:282 pp. – With averages and variabilities based on 3110 measurings on boys and 1473 on girls from the ages of one to nineteen years.
   3. Meredith HV (1935) Univ Iowa studies in child welfare 11(3).
   4. Peatman JG, Higgons RA (1938) Growth norms from birth to the age of five years: a study of children reared with optimal pediatric and home care. Am J Diseases Children 55:1233-1247.
   5. Simmons KW (1944) Monographs Soc Research in Child Develop 9(1).
4. Body mass excess

MitoPedia concepts: MiP concept 

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MitoPedia:BME