MacArthur SES & Health Network
MacArthur SES & Health Network


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Central Body Fat

Summary prepared by Karen Matthews in collaboration with the Allostatic Load Working Group. Last revised August, 1996.

Chapter Contents

  1. Definition
  2. What aspect of allostasis does central body fat potentially measure?
  3. How is central body fat measured?
  4. Does central body fat predict disease?
  5. Does central body fat vary with psychosocial factors?
  6. Does central body fat vary with SES?
  7. Further Readings

Definition

Accumulation of fat in the abdominal area, adjusted for total body fat, or adjusted for an index of obesity, such as body mass index.

What aspect of allostasis does central body fat potentially measure?

Although genetic factors may account for up to 50% of the variance in body fat distribution, central body fat also increases with age after young adulthood and is correlated with life style variables, e.g. smoking, and with markers of stress. These findings suggest that central body fat may be an indirect measure of cumulative burden, which, is in part, determined by environmental factors.

How is central body fat measured?

Epidemiological studies have used waist/hip ratio (WHR) because of the necessity to screen large numbers. WHR is usually measured over underwear in the clinic setting using inelastic tape. The technician measures the waist as the narrowest part of the torso, which is usually above the umbilicus, and the hips as the maximal part of the buttocks, taking care to measure a horizontal plane without compressing the skin. To do the latter, the technician must squat at the individual's side to identify the maximal part of the buttocks. Because some individuals are exceptionally obese, some investigators use anatonomical anchor points (e.g. 1" above umbilicus) to identify measurement site. WHR has also been measured in the home by the participant and is highly correlated with technician measured WHR.

Body mass index is weight in kg divided by height in meters squared, although there are many other indices of body mass.

% body fat, nonessential fat mass, and fat free body mass can be calculated from skinfold thicknesses measured at seven sites. Total body fat and lean tissue mass can also be measured using bone densitometry.

Computed axial tomography (CAT) scans are used to measure subcutaneous truncal-abdominal fat. Because exposure to radiation is part of the procedure and the procedure is expensive, this technique is not used in large scale epidemiology studies. If the investigational purpose is to measure abdominal fat, then the scans are usually a single scan between 4th and 5th lumbar vertebrae.

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Does central body fat predict disease?

Central body fat as estimated by WHR is related to risk of myocardial infarction, stroke, non-insulin dependent diabetes mellitus, hypertension, endometrial carcinoma, and polycystic ovary syndrome in epidemiological investigations. It also predicts mortality in white and African American men and in white women. It covaries with several biological risk factors for disease, e.g. with blood pressure, low HDL-C, and high insulin resistance. Several epidemiological analyses show that gender differences in CVD morbidity are eliminated by controlling for WHR, suggesting that gender differences in disease are due in part to pathogenic processes associated with central body fat.

Does central body fat vary with psychosocial factors?

Gothenburg, Sweden Study and the Healthy Women Study report that abdominal obesity is correlated with reports of stress and distress. WHR might be associated with weight cycling, cortisol abnormalities, and is associated with smoking. Experimental minimal data suggest a preferential deposition of fat in the abdominal area after stress exposure.

Does central body fat vary with SES?

Socially subordinate female monkeys have more central body fat.

Further Readings

Bjorntorp P. Behavior and metabolic disease. International Journal of Behavioral Medicine, 1996, 3:285-302.

Bouchard C, Tremblay A, Despre JP, et al. The response to long-term overfeeding in identical twins. New England Journal of Medicine, 1990, 322:1477-82.

Folson AR, Kaye SA, Sellers TA, et al. Body fat distribution and 5-year risk of death in older women. JAMA, 1993, 239:483-487.

Jackson AS, Pollock ML. Practical assessment of body composition. Physician and Sports Medicine, 1978, 13:76-90.

Jackson AS, Pollock ML, & Ward A. Generalized equations for predicting bone density of women. Medicine and Science in Sports and Exercise, 1980, 12:175-182.

Rodin J. Determinants of body fat localization and its implications for health. Annals of Behavioral Medicine, 1992, 14:275-281. girths as predictors of mortality in black and white women. Archives of Internal Medicine, 1992;152:1257-1262.

Schoen RE, et al. Anthropometric variables do not accurately estimate visceral adipose tissue in obese individuals. In press.

Vague J, Bjorntorp P, Guy-Grand, et al. (Eds). Metabolic Complications of Human Obesities. The Netherlands: Elsevier, 1984.

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