Body fat limits

[Guest guest]

fyi:

ran across this in:

Auerbach: Wilderness Medicine, 4th ed., Copyright © 2001 Mosby, Inc.

page 1279.

Body fat level approaching 6% indicates impending lean body mass deterioration in the fasting individual.[28] Essential fat stores (fat in bone marrow, heart, lungs, liver, kidneys, intestine, muscle cell membranes, and the central nervous system) are necessary to maintain of life and prevent decompensation. Essential fat stores constitute 3% to 4 % of body weight. Total body fat depletion in previously nonobese individuals occurs at approximately 50% body weight loss. In fasting uncomplicated by disease the time until death is largely determined by the size of fat stores and the time to reach the 3% level of essential fat. Low fat stores are not the cause of death, but their diminution contributes to breakdown of homeostasis

1280and impairment of physiologic function. Fat stores protect function. Typical fat stores in humans are 10 to 15 kg (including 2.1 kg of "essential" fat), or approximately 27% of body weight. A well-nourished adult has sufficient fat stores to sustain life for 60 to 70 days. Death has been reported sooner in voluntary hunger strikers and may be related to simultaneous fluid restriction and the lack of "will to live."

A loss of greater than 50% of the lean body mass is also predictive of death. Remaining body fat and protein reserves are difficult to measure accurately. The body mass index (BMI, weight in kg divided by height in m2 ) is a convenient method to assess risk of mortality in severely starved individuals. Before the unfortunate war and famine in Somalia, the lowest BMI compatible with life was thought to be 13 in males and 11 in females.[31] [23] found that a BMI of 10 could be compatible with life under conditions of specialized hospital care. A BMI of 10 may be compatible with life among certain somatotypes in a warm climate, but other races in colder climates may face death before reaching the low BMI level noted in Somalia.