Physical Performance and Metabolic Recovery Among Lean, Healthy Men Following a Prolonged Energy Deficit

Abstract

Previous studies have demonstrated that full recovery from weight loss may take months or years. The present investigation examined short-term recovery (5 wks "post") of physical performance (muscular strength, muscular power, vertical jump), body composition, metabolic hormones (testosterone, luteinizing hormone, sex hormone binding globulin, insulin-like growth factor-1, triiodothyronine, thyroxine, thyroid binding globulin, and thyroid-stimulating hormone) and metabolic markers (transferrin, ferritin, prealbumin, glycerol, nonesterified fatty acids, high-density lipoproteins, and lactate) in 10 healthy young men after an 8-week Army course with an energy deficit (1000 kcal/d) and loss of body mass (-12%). Subjects ate ad libitum after the course ended ("post"). Body composition was determined by dual-energy X-ray absorptiometry; strength from a simulated power clean, power from body mass and jump height, and metabolic hormones were measured in morning-fasted blood by radioimmunoassay. With the exception of transferrin and glycerol, all study parameters were significantly (p<.05) altered by the training course. At 5 weeks post fat-free mass along with all physical performance measures returned to initial levels; however, fat mass had significantly (p<.05) increased over initial levels. Also, with the exception of lactate, all measured hormones and markers were close to initial levels and within normal ranges. Reported complications during recovery included sleep irregularities, diarrhea, loss of motivation and feelings of fatigue. While the long range effect of this energy deprivation experience is uncertain, these data do suggest that severe weight loss does not result in lasting alterations of the contractile and metabolic properties of skeletal muscle in young, lean, healthy men.

How dieting makes some fatter: from a perspective of human body composition autoregulation

“…In more recent years, similar body weight and fat overshooting have also been reported in young men at the US Army Ranger School recovering from about 12% of weight lost following 8-9 weeks of training in a multistressor environment that includes energy deficit and sleep deprivation (36)(37)(38) . Nindl et al (36) found that at week 5 in the post-training recovery phase, body weight had overshot by 5 kg, reflected primarily in large gains in fat mass, with all ten subjects showing higher fat mass than before weight lost.…”

“…Nindl et al (36) found that at week 5 in the post-training recovery phase, body weight had overshot by 5 kg, reflected primarily in large gains in fat mass, with all ten subjects showing higher fat mass than before weight lost. Similarly, in young male volunteers participating in another 8-week US Army Ranger course that involved four repeated cycles of restricted energy intake and refeeding, Friedl et al (38) found that more weight was regained than lost at week 5 of recovery following training cessation, with fat overshooting representing an increase of 40 % in body fat above pre-training levels.…”

Utility of Measuring Insulin-Like Growth Factor-I for Assessing Military Operational Stress: Supporting Future Force Warrior from the Bench Top to the Battlefield

“…The physiological strain produced by these operational stressors can have deleterious effects on muscle mass, endocrine and metabolic function, as well as physical and mental performance (Friedl et al, 1994;Friedl, 1999;Friedl et al, 2000;Nindl et al, 1997;Nindl et al, 2002;Nindl et al, 2003a;Nindl et al, 2003b) (see Figure 1). A goal of the Army Medical Research and Materiel Command's (MRMC) biomedical research program is to identify useful biomarkers that are indicative of nutritional and physiological status that can be assessed rapidly, with minimally or non-invasive collection methods.…”

“…Friedl and colleagues performed experimental studies characterizing the physiological responses of soldiers participating in the U.S. Army Ranger Training Course (Friedl et al, 1994;Friedl et al, 2000;Nindl et al, 1997). The data provide insight into the adaptive process that occurs as soldiers cope with sustained physical work, energy restriction and sleep disruption.…”

“…In contrast, IGF-I appears to be a more responsive and selective biomarker of energy status due to its rapid response to depletion and repletion (Baxter et al, 1998) In a study examining endocrine and metabolic recovery responses, Nindl et al (1997) measured IGF-I, transferrin, ferritin, and prealbumin before, at the end of the U.S. Army Ranger Training Course, and after 5 weeks of recovery. The five week recovery period produced a rebound effect such that body mass was significantly higher than measured before starting the course.…”