Physical trainers have found that when aerobics experts, who tend to have relatively high metabolic rates, gain weight by increasing the number of calories they consume, their metabolisms continue to be higher than average. They will thus burn more calories at their new weight than do people for whom the new weight is normal. As a result, aerobics experts will ultimately lose the newly gained weight until their weight matches their high metabolic rate.
The conclusion of the argument above depends on which of the following assumptions?
(A) Physical trainers disagree over whether metabolic rates can be increased or decreased through the use of targeted hormone treatments.
(B) The metabolisms of people who are not aerobics experts are more variable than the metabolisms of people who have been aerobic experts.
(C) People who are at their usual weights find it equally difficult to gain or to lose weight due to the constant speed of their metabolisms.
(D) Not many aerobics experts who have gained weight by increasing caloric intake continue to consume substantially more calories than do people for whom the higher weight is normal.
(E) The number of calories that an individual burns in a day is determined by the amount consumed that day and not by the individual's current weight.