Explain this....

So my scale hasn't moved in months so I went to Target last night to buy a new one figuring the old one must be broken. A bag of Resees peanut butter heart-shaped chocolates ended up in my cart. After I set up the new scale next to the old one, realized that they both read the same number, I curled up in my bed with my bag of hearts and devoured the entire bag (yup, the entire bag) and drifted off into a chocolate induced coma. I get up this morning, shuffle my way through the empty bag and all its wrappers on the floor, step on both scales......low and behold.....three pounds down. Broke through a plateau. WTF.