Men and women soldiers start with different body compositions: men typically have more total body weight and lean tissue, while women have more body fat. These differences remain during intense...
Mechanism
Synthesis from 1 study
Men and women start with different body shapes because of hormones — men have more muscle, women have more fat. During intense training, men burn more muscle for energy while women hold onto fat longer — but when the training gets extreme, both burn so much fat that the difference disappears, as...
Most probable mechanism
Men and women start with different amounts of muscle and fat because of hormones and genetics, and during intense training, men use more muscle for energy while women hold onto fat longer — but when training gets really extreme, both sexes burn fat so much that the difference disappears. This is seen in soldiers during Ranger training, where men kept more muscle and women lost fat until both ended up with similar fat levels.
Baseline sex differences in lean mass and adipose tissue distribution are established by hormonal regulation during puberty and maintained through adulthood, with higher testosterone in males promoting muscle accretion and higher estrogen in females favoring subcutaneous fat storage.
During prolonged caloric deficit from intense military training, males exhibit greater reliance on fat-free mass as an energy substrate due to higher muscle mass and greater metabolic flexibility, preserving lean tissue relative to females.
Females exhibit greater metabolic efficiency in preserving fat mass during moderate energy deficit, likely due to estrogen-mediated suppression of lipolysis and preferential mobilization of non-adipose energy sources, but under extreme caloric restriction, adipose tissue becomes a dominant fuel source, eroding baseline sex differences in fat mass.
Evidence from Studies
Supporting (1)
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Limited Sex Differences in Energy Balance and Body Composition during 61+D of US Army Ranger Training
Contradicting (0)
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