That’s not redundant. It’s not about size and shape. The problem of trying to measure fatness in the biggest terrestrial animals was highlighted in this report (1) in the journal Obesity by investigators at the University of Alabama that included a new friend of mine, Dr. David Allison, who’s now with the Indiana University-Bloomington School of Public Health. We are new-found friends because of our mutual admiration of the late Dr. Albert Stunkard.
It has long been found that elephants in zoos have a lot of trouble making baby elephants. Fifty percent of lady elephants in zoos have irregular reproductive cycles or no cycles. That has been attributed by zoologists to be related to their obesity. Thirty-three percent of female African elephants in North American zoos are classified as obese. But obesity in elephants has been based on body condition scores (BCS) and body mass index (BMI). BCS are a subjective assessment based on things like pinching their skin to see how fat that is. BMI is probably just as sloppy a determination of fatness in elephants as it is in humans.
These guys used Deuterium (2H) containing water to measure fatness. 2H is a nonradioactive isotope of hydrogen (1H). When deuterated water is administered to animals, it is diluted by the 1H in water molecules, providing an estimate of total body water (TBW). TBW is assumed to be restricted to the animal’s fat free mass (FFM); thereby, using the standard mammalian hydration constant, based on TBW of 73%, FFM can be calculated. Fat mass (FM) is then inferred by subtracting FFM from weight.
Twenty-two female elephants from 8 zoos were studied. Forty-one percent had abnormal reproductive cycles. Fat mass ranged from 5 to 16 % and increased with age. They could not determine what constituted problematical obesity in elephants because there was not enough correlation of FM with problems of obesity such as glucose, insulin, leptin or inflammatory markers. Elephants, as well as other big animals do not have much subcutaneous fat, because they don’t want to have much insulation. They need to be able to get rid of heat.
They showed that the usual ways of measuring obesity in elephants did not correlate with percentage fat mass by this presumably better determination and also fatness of elephants did not have anything to do with reproductive abilities. That seemed to be related only to the age of the elephants. Female elephants in zoos are getting too old to make babies, and reproduction in zoos is not self sustaining of the elephant population.
Which just goes to show you, you can’t judge the fatness of an elephant by the size and shape of their pachydermic cover. That’s also true about the cover of humans.
1. Chusyd DE et al. Adiposity and Reproductive Cycling Status in Zoo African Elephants. Obesity January 2018; 26(1):103-110
John DiTraglia M.D. is a Pediatrician in Portsmouth. He can be reached by e-mail- firstname.lastname@example.org or phone-354-6605.