In sum, severe calorie restriction and testosterone replacement did not affect muscle protein synthesis but increased muscle mass during the severe calorie restriction phase compared to the placebo.
BENEFITS OF HIGH TESTOSTERONE, PROTEIN ANABOLISM, AND PRESERVING MUSCLE MASS WHILE DIETING SUMMARY.
- The benefits of high testosterone levels before intense training and calorie restriction led to greater retention of muscle mass.
- Testosterone administration in the presence of severe calorie restriction did not affect muscle protein synthesis.
RESEARCH UPDATE: 9/24/2022: MARINES WITH HIGH TESTOSTERONE LEVELS BEFORE INTENSE TRAINING AND FOOD RESTRICTION LOSE LESS MUSCLE
Previous studies have found that intense training, stress, and diet influence testosterone levels. A previous study found that healthy participants subjected to a 21-day, 40% energy deficit, achieved with increased physical training and decreased food intake, lost 3.2 kg body mass, which coincided with a 16% decrease in total testosterone. (4, 5)
Study
Researchers examined how testosterone levels before 18 days of rigorous training and food restriction would affect military men’s body composition. The military training comprised 4 phases over ~18 days:
(1) 10-day academic classroom training,
(2) 2.5-day survival skills training conducted in a natural environment,
(3) 2.5-day evasion training, and
(4) 2.5-day captivity training.
Severe energy deficit occurs during phases 2 to 4(~7 d). Participants were provided minimal food during phases 2 and 3 (5 days), which included 1 combat ration (Meal ready-to-eat, ~1300 kcal) per participant and a limited amount of vegetables and meat to ration between team members.
During phase 4, participants were “captured” and placed in a stressful simulated captivity environment. They were provided water regularly but were only given two meals during phase 4 (~2.5 days); each meal consisted of a piece of bread and approximately one cup of rice. Fasting and energy deficiency reduce testosterone concentrations in males, which has been suggested as an adaptive response to minimize energy requirements.(6, 7)
Results
At the end of the study, the researchers found that those marines who had higher/maintained testosterone levels after the 7 days of stressful training and calorie restriction maintained greater lean mass, more fat loss around in the upper body, and lower rates of muscle protein breakdown than those who had lower testosterone levels following the same military training. (8)
Greater testosterone levels in the men before the military training started may have contributed to these positive effects compared to the men that started the military training with lower testosterone levels at the start of training. The men who preserved testosterone levels had greater fat mass at the onset of training may have served, in part, as a protective factor, as more pre-training fat mass was associated with greater decrements in fat mass and smaller declines in testosterone.
The author suggested that “maintenance of normal testosterone during training may indicate a more resilient phenotype, which may identify individuals better suited for subsequent high-stress/specialized training and may need less recovery time between consecutive missions. Interventions that prevent decrements in testosterone during strenuous military training should be investigated as a method to reduce fat-free mass loss, potential physical performance declines, and other detrimental consequences of low testosterone.”
TESTOSTERONE DOSAGE FOR MUSCLE GROWTH: DOSE-DEPENDENT RESPONSE
Testosterone increasese protein synthesis and enhances lean muscle mass. One of the first studies on testosterone administration found a dose-dependent increase in lean muscle mass with higher dosages of testosterone.(1) Another study found that 600 mg of testosterone increased muscle mass in conjunction with resistance exercise. (2) Given the powerful anabolic effects of testosterone, it would be reasonable to assume that testosterone could preserve muscle mass during a calorie deficit.
The Military Is Interested in the Benefits of High Testosterone for Retaining Muscle Mass
How does the military aim to maintain lean muscle mass in soldiers who experience low-calorie availability during military operations? It is well-established that soldiers who undergo severe calorie restriction and engage in rigorous exercise may experience a decline in lean mass. In light of this, what role does testosterone play in preserving muscle mass in such circumstances?”
Researchers placed subjects on a 28-day calorie-restricted diet, 55% calorie deficit with protein set at 1.6 g/kg/day while taking 200 mg of testosterone enanthate or a placebo. This is on the low side of protein, as most studies suggest that a calorie-restricted diet needs more protein to preserve lean muscle mass. The subjects also had 60 minutes of aerobic-based exercise to mimic the activities of daily military life.
The exercise protocol comprised low, moderate, and high-intensity exercises consisting of treadmill exercise, elliptical, stationary bike, walking, and weighted backpack carrying exercises (i.e., 30% of their body mass). The researchers measured changes in muscle mass, fat loss, and protein synthesis during and 11 days after, in which the calories were dramatically increased.
BENEFITS OF HIGH TESTOSTERONE DURING SEVERE CALORIE RESTRICTION
At the end of the study, the researchers found no difference in muscle protein synthesis between the two groups (i.e., testosterone vs. placebo). Total Testosterone and Free Testosterone increased in the group receiving testosterone, while total testosterone decreased by 20% in the placebo group, and free testosterone decreased by 42% during the energy deficit.
Severe calorie restriction (55% calorie reduction) seemed to reduce muscle protein synthesis responses regardless of whether or not they were receiving testosterone. There were, however, positive anabolic responses from testosterone administration. The testosterone group increased lean mass (i.e., 5.5 lbs.) while in a caloric deficit, while the group receiving the placebo had no change in muscle mass. Fat mass decreased in both groups by 8.8-11 pounds. After the groups returned to their normal diet, both groups increased lean muscle mass (i.e., 2.2 lbs.). (3)
In sum, the benefits of high testosterone during severe calorie restriction did not affect muscle protein synthesis but increased muscle mass during the severe calorie restriction phase compared to the placebo. No resistance exercise was performed in this study, so it would be interesting to see if this study was replicated with resistance exercise.
REFERENCES
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