Human physiology studies have explored the effects of physical exercise and hypoxia on peripheral cholecystokinin (CCK) metabolism. In a study involving 32 male students, participants were divided into normoxic (NOR) and hypoxic (HYP) groups. Acute normoxic exercise increased CCK levels, while acute hypoxic exercise decreased them. Chronic training under normoxic or hypoxic conditions did not affect CCK responses, despite changes in body fat. These findings suggest that CCK metabolism is more sensitive to acute changes in energy expenditure and may be influenced by serotoninergic activity and tissue oxygenation. Another study investigated the association between high altitude and very low birth weight (VLBW), independent of maternal economic status. In Bolivia, high altitude was linked to reduced birth weight and increased infant mortality, regardless of income level. Birth weights were lower in high-altitude regions, and the frequency of VLBW was higher. High altitude also correlated with an increased head-to-body weight ratio. These results indicate that high altitude, independent of economic status, promotes VLBW and altered body shape at birth.Human physiology studies have explored the effects of physical exercise and hypoxia on peripheral cholecystokinin (CCK) metabolism. In a study involving 32 male students, participants were divided into normoxic (NOR) and hypoxic (HYP) groups. Acute normoxic exercise increased CCK levels, while acute hypoxic exercise decreased them. Chronic training under normoxic or hypoxic conditions did not affect CCK responses, despite changes in body fat. These findings suggest that CCK metabolism is more sensitive to acute changes in energy expenditure and may be influenced by serotoninergic activity and tissue oxygenation. Another study investigated the association between high altitude and very low birth weight (VLBW), independent of maternal economic status. In Bolivia, high altitude was linked to reduced birth weight and increased infant mortality, regardless of income level. Birth weights were lower in high-altitude regions, and the frequency of VLBW was higher. High altitude also correlated with an increased head-to-body weight ratio. These results indicate that high altitude, independent of economic status, promotes VLBW and altered body shape at birth.