Define basal metabolic rate.

Discuss dietary practices sometimes employed by athletes to manipulate body composition.

the rate of metabolism measured under standard or basal conditions «awake, at rest, fasting»
OR
the lowest rate of body metabolism that can sustain life ✔

Gaining muscle mass:
adequate protein intake must be consumed «in addition to correct strength training» ✔

changes in body composition as a result of this strategy occur slowly over time ✔

excess protein cannot be stored in the body and is excreted ✔

there are risks associated with excessive protein intake relating to damaging the kidneys «in addition to causing dehydration and constipation» ✔

Reducing fat mass:
low energy intake «negative energy balance» causes the body to metabolize stores of fat «causing them to lose weight» ✔

associated with lean athletes and particularly women ✔

there are risks associated with losing excessive levels of body fat that can prevent the normal functioning of the body «eg amenorrhea / electrolyte imbalance / development of gall stones » ✔

Dehydration:
participants may deliberately avoid or restrict food and fluid intake in order to remain weight category 
OR
to gain entry to a lower weight category «eg boxing/martial arts and rowing» ✔ there are risks associated with dehydration «due to the impact on the functioning of the cardiorespiratory system» ✔

Most defined well.

Surprisingly poorly answered. I like this question. It seems simple but is applied and requires a broader perspective, so it highlights deficiency in this important skill.