Heavy refers to a measurement of weight, which is only relative, since it is essentially the measure of the force of gravity on an object, such that the weight of an object can vary if gravity varies. Just thought I'd point out this irony when we're talking aout an alien based around gravity. Unless you were referring to his mass, which is somewhat more constant.
Not sure what unit of measurement you'd prefer, so I'll try a default imperial system. I'd say he looks to be seven or eight feet tall, maybe nine at the most. Hard to say about the rest, but my guess at his weight under normal earth conditions would be half a ton at least. Maybe quite a bit more.