Question

When energy balance in the body is positive, body mass decreases?

Answer 1

The energy balance when being positive, body mass does not decreases, in fact increases.

Explanation:

Energy is a measure in relevance to the body mass, either be it the kinetic energy or potential energy, each is defined in relevance to the body mass.  

As we know, K.E.= $\frac{1}{2}m v^{2}$

And, P.E. = mgh

Both as evident has, Energy is directly proportional to mass

Thus, when the energy balance in the body is positive, body mass will increase.