【单选题】Researchers have found that when very overweight people, who tend to have relatively low metabolic rates, lose weight primarily through dieting, their metabolisms generally remain unchanged. They will...
A.
Relatively few very overweight people who have dieted down to a new weight tend to continue to consume substantially fewer calories than do people whose normal weight is at that level.
B.
The metabolisms of people who are usually not overweight are much more able to vary than the metabolisms of people who have been very overweight.
C.
The amount of calories that a person usually burns in a day is determined more by the amount that is consumed that day than by the current weight of the individual.
D.
Researchers have not yet determined whether the metabolic rates of formerly very overweight individuals can be accelerated by means of chemical agents.
E.
Because of the constancy of their metabolic rates, people who are at their usual weight normally have as much difficulty gaining weight as they do losing it.