TESTOSTERONE By Robbie Durand
106 MD musculardevelopment.com July 2019Bodybuilding is a sport in which athletes need to cut body fat to
show muscular defi nition while maintaining lean muscle mass. Just
about every guy on the planet wants six-pack abs, but having low
body fat can have negative consequences on a man’s testosterone.
Energy availability is a scientifi c concept describing how much
energy is available for essential metabolic functions such as
reproduction, immunity and skeletal muscle mass. Just about every
man knows that when women start losing excess body fat, their
endocrine system shuts down and they oft en experience amenorrhea
or absence of a menstrual cycle. Women need a certain amount
of body fat to maintain healthy reproductive function, but new
research is also discovering that men who lose excess body fat for a
bodybuilding show or excessive exercise also have lower endocrine
and reproductive function. Many men will increase the amount of
aerobic exercise while simultaneously decreasing total calories to
reduce body fat leading up to a bodybuilding show. Here is what a
few studies had found when men went on a low-calorie diet:
- In one case study, an athlete dieted for six months prior to
competition, starting with self-reported eating of ~2,800 kcal at the
start of his diet and gradually decreased it toward ~2,500 kcal per
day at the end of the diet. He performed fi ve hours of resistance
training per week, 1× 40-minite high-intensity interval training
(HIIT) per week and 1× 30-minute low-intensi steady state (LISS)
per week, thus expending ~600 kcal per day in exercise energy
expenditure. At the end of six months, the athlete’s testosterone
levels decreased by 76 percent, whereas cortisol levels increased by
107 percent, and anxie increased. This was also accompanied by a
21 percent reduction in lean muscle mass. - Another interesting study measured hormone response to three
weeks of energy restriction and two weeks of refeeding among 32
young men. The subjects were eating a meager 1,350 calories per
day. Subjects lost on average 12 pounds during the three weeks
of calorie restriction. Resting metabolic rate was reduced by 266
calories per day, the activity of the sympathetic nervous system was
reduced by 38 percent, insulin by 54 percent, 3-3~-5-triiodothyronine
(T3) by 39 percent, and testosterone by 11 percent. All results indicate
powerful short-term eff ects of shift s in dieting on male physiology. - Another study measured the eff ects of low and high protein on
lean muscle mass and endocrine markets during a calorie-restricted
diet. Subjects lost on average 6 pounds of bodyweight and the
anabolic muscle response to a protein-rich meal was lower among
those who consumed low protein versus the higher protein groups;
the loss of lean muscle mass was also greater in low protein versus
the high protein group, suggesting protective eff ects of higher
protein intakes during short-term calorie restriction. Interestingly
enough, serum testosterone, free testosterone and total IGF-1 were
decreasing in all protein groups, indicating that despite high protein
intake, without suffi cient calories, anabolic hormones decreased.
The author concluded that the adverse eff ects of low caloric intake
in bodybuilders are seen in which caloric intake falls below <20 kcal/
kg of lean m uscle mass, something that has been observed in the
end stage of contest diets. This approach resulted in muscle and
strength loss and in the study, those with the lowest observed body
fat had signifi cant mood disturbance, and hormonal imbalances
Long-Term Calorie Restriction
Can Impair Testosterone
Just about every guy on the planet
wants six-pack abs, but having
low body fat can have negative
consequences on a man’s testosterone.
occurred. To avoid the negative consequences of dieting, incorporate
a structured food plan with at least 25 kcals/kg of lean muscle mass
in conjunction with high protein intake (>1.6 grams of protein per kg of
bodyweight) and adding resistance exercise.Robbie Durand works for VPXSPORTS.COMReference:
Fagerberg P. Negative Consequences of Low Energy Availabili in Natural Male
Bodybuilding: A Review. Int J Sport Nutr Exerc Metab 2017; May 22:1-31. doi: 10.1123/
ijsnem.2016-0332