High-altitude anorexia leads to a hormonal response pattern modulated by both hypoxia and caloric restriction (CR). The purpose of this study was to compare altitude-induced neuroendocrine changes with or without energy imbalance and to explore how energy sufficiency alters the endocrine acclimatization process. Twenty-six, normal-weight, young men were studied for three weeks. One group (HYPO, n = 9) stayed at sea level and consumed 40% fewer calories than required to maintain body weight (BW). Two other groups were deployed to 4300m (Pikes Peak, CO) where one group (ADQ, n = 7) was adequately fed to maintain BW and the other (DEF, n=10) had calories restricted as above. HYPO experienced a typical CR induced reduction in many hormones such as insulin, testosterone, and leptin. At altitude, fasting glucose, insulin, and epinephrine exhibited a muted rise in DEF compared to ADQ. Free T₄, TSH, and norepinephrine showed similar patterns between the two altitude groups. Morning cortisol initially rose higher in DEF than ADQ at 4300m, but the difference disappeared by day 5. Testosterone increased in both altitude groups acutely, but declined over time in DEF only. Adiponectin and leptin did not change significantly from SL baseline values in either altitude group regardless of energy intake. These data suggest that hypoxia tends to increase blood hormone concentrations, but anorexia suppresses elements of the endocrine response. Such suppression results in the preservation of energy stores, but may sacrifice the facilitation of oxygen delivery and the use of oxygen efficient fuels.