Agreed with the others, if your diet is "borderline" at best now with calorie intake, adding a calorie dense supplement like MM will not help you.
No matter how good something is, if it makes you exceed your calorie needs, you will not see the results you want.
On a tangent here, it amazes me, folks see something on TV, or read something in a study that this or that is so healthy, and prevents this or that, so they unconsciously add it to their dietary intake, without subtracting something equally as calorie dense, think they are being healthy, and end up adding weight and can't figure out why.