Answer
The body's weight will change.
Work Step by Step
A body's mass is the constant value and remains unchanged no matter the body is moved anywhere.
The body's weight, however, is the gravitational force the earth exerts on the body and depends upon how far the body is from the earth's center.
$$W=G\frac{Mm}{r^2}$$
As we can see, when the body is moved from sea level to the top of a mountain, its distance from the earth's center $r$ increases, so the body's weight $W$ will decrease.
