King Grub
2014-06-02, 12:05
Energy deficit (ED) diminishes fat-free mass (FFM) with concomitant reductions in anabolic hormone secretion. Although consuming high protein diets preserves FFM during ED, the effects of dietary protein on circulating anabolic hormones and their potential relationships with FFM in response to short-term ED are not well described.
PURPOSE:
Determine the anabolic hormonal response to habitual consumption of high protein diets during short-term ED, and to evaluate whether modulations in testosterone and IGF-I components are associated with the documented preservation of FFM subsequent to consuming high protein diets.
METHODS:
In this randomized controlled trial, 33 adults were assigned diets providing protein at 0.8 (recommended dietary allowance; RDA), 1.6 (2X-RDA), and 2.4 (3X-RDA) g/kg/d for 31 days. Testosterone, sex-hormone binding globulin (SHBG) and insulin-like growth factor-I (IGF-I) system components were assessed after a 10-day period of weight-maintenance (WM) followed by a 21-day period of ED (40%). Associations between the change in FFM and anabolic hormone levels were determined.
RESULTS:
As compared to WM, and regardless of dietary protein intake, there was a decrease (P < 0.05) in total testosterone (WM=545.9±35.8 ng/dL, ED=460.9±35.3 ng/dL), free testosterone (WM=13.08±1.2 pg/mL, ED=10.14±1.2 pg/mL), total IGF-I (WM=190.6±9.4 ng/mL, ED=163.8±9.4 ng/mL), and acid-labile subunit(WM=1783.7±61.6 μg/mL, ED=1626.5±61.6 μg/mL, whereas SHBG (WM=44.8±10.2 nmol/L, ED=52.7±10.2 nmol/L, IGF binding proteins (IGFBP-1, WM=2.75±0.7 ng/mL, ED=4.43±0.7 ng/mL), IGFBP-2(WM=8.2±3.7 ng/mL, ED=15.9±3.7 ng/mL) and IGFBP3 (WM=188.4±7.2 ng/mL, ED=199.9±7.2 ng/mL) increased (P < 0.05) during ED. There was no energy-by-protein interactions on any hormones or IGF-I system components measured. Changes in FFM in response to ED were negatively associated with ALS (r = -0.62, P < 0.05) in 2X-RDA; however, no other relationships were observed.
CONCLUSION:
Consuming a high protein diet does not impact the androgenic and IGF-I system response to short-term ED. Furthermore, these data suggest that the protective effects of high protein diets on FFM during ED are likely not influenced by anabolic hormone concentrations.
High Protein Diets Do Not Attenuate Decrements In Testosterone And IGF-I During An Energy Deficit. ACSM Annual Meeting May 28 2014.
PURPOSE:
Determine the anabolic hormonal response to habitual consumption of high protein diets during short-term ED, and to evaluate whether modulations in testosterone and IGF-I components are associated with the documented preservation of FFM subsequent to consuming high protein diets.
METHODS:
In this randomized controlled trial, 33 adults were assigned diets providing protein at 0.8 (recommended dietary allowance; RDA), 1.6 (2X-RDA), and 2.4 (3X-RDA) g/kg/d for 31 days. Testosterone, sex-hormone binding globulin (SHBG) and insulin-like growth factor-I (IGF-I) system components were assessed after a 10-day period of weight-maintenance (WM) followed by a 21-day period of ED (40%). Associations between the change in FFM and anabolic hormone levels were determined.
RESULTS:
As compared to WM, and regardless of dietary protein intake, there was a decrease (P < 0.05) in total testosterone (WM=545.9±35.8 ng/dL, ED=460.9±35.3 ng/dL), free testosterone (WM=13.08±1.2 pg/mL, ED=10.14±1.2 pg/mL), total IGF-I (WM=190.6±9.4 ng/mL, ED=163.8±9.4 ng/mL), and acid-labile subunit(WM=1783.7±61.6 μg/mL, ED=1626.5±61.6 μg/mL, whereas SHBG (WM=44.8±10.2 nmol/L, ED=52.7±10.2 nmol/L, IGF binding proteins (IGFBP-1, WM=2.75±0.7 ng/mL, ED=4.43±0.7 ng/mL), IGFBP-2(WM=8.2±3.7 ng/mL, ED=15.9±3.7 ng/mL) and IGFBP3 (WM=188.4±7.2 ng/mL, ED=199.9±7.2 ng/mL) increased (P < 0.05) during ED. There was no energy-by-protein interactions on any hormones or IGF-I system components measured. Changes in FFM in response to ED were negatively associated with ALS (r = -0.62, P < 0.05) in 2X-RDA; however, no other relationships were observed.
CONCLUSION:
Consuming a high protein diet does not impact the androgenic and IGF-I system response to short-term ED. Furthermore, these data suggest that the protective effects of high protein diets on FFM during ED are likely not influenced by anabolic hormone concentrations.
High Protein Diets Do Not Attenuate Decrements In Testosterone And IGF-I During An Energy Deficit. ACSM Annual Meeting May 28 2014.