Dr.ObesityLA said:The honest answer is that the effect is real, the magnitude is contested, and the individual variation is larger than either.
There is a second half to this that has not been said yet. Whatever the answer turns out to be, the method for getting there is the same: state the assumption, do the arithmetic in public, and invite the correction. That is slower than asserting, and it is the only version that survives being wrong.
That is the short version; the long version is somebody else's post.