Objective: To quantify the health, fitness, and physiological responses to military training of Officer Cadets from a Gulf Cooperation Council country. Methods: One hundred and nineteen Officer Cadets volunteered; body composition, core body temperature, aerobic fitness, hydration status (urine osmolality), cardiovascular strain, physical activity (3-dimensional accelerometry), and energy expenditure (doubly labelled water) were measured over 5-days of Basic Training (BT), Army Training (AT), Navy Training (NT), and Air Force Training (AFT). Results: There were no differences between courses for body mass index (mean all courses: 24.1 ± 4.1 kg.m−2) or peak core body temperature (mean all courses: 38.1 ± 0.4 °C) (p > 0.05). AT body fat (19.8 ± 3.6%) and BT VO2 max (36.8 ± 11.6 mL.kg−1.min−1) were lower than the other courses (BT, 26.1 ± 8.1; NT, 26.0 ± 6.0; AFT, 24.7 ± 6.1%) and (AT, 44.8 ± 9.6; NT, 45.0 ± 7.5; AFT, 44.6 ± 5.2 mL.kg−1.min−1), respectively (p < 0.05). NT urine osmolality (979 ± 90 mOsmol.kg−1) was similar to BT (946 ± 181 mOsmol.kg−1p > 0.05) but lower in AT (868 ± 144 mOsmol.kg−1, p < 0.05) and AFT (883 ± 121 mOsmol.kg−1, p < 0.05). Cardiovascular strain during NT (22 ± 5 %HRR) was lower than other courses (range, 25 ± 4–29 ± 3% Heart Rate Reserve) (p < 0.05). Physical activity level during AFT (1.70 ± 0.18 AU) was lower than other courses (range, 1.86 ± 0.21–1.92 ± 0.18 AU) (p > 0.05). Conclusion: Positive developments were apparent from BT leading into other courses. Potential exists to increase physical training volume on all courses, which may improve participants’ aerobic fitness, body composition, and health.