Answer:
CDC is the Center for Disease Control, it's a federal organisation in the United States. Its mandate is to analyse, control and prevent any form of health epidemic issues. For example, in the measles crisis right now, CDC is involved in coordinating the quarantines, the treatment and so on.
Part of CDC's role is also to emit recommendations for the general public health, especially in prevention of epidemic issues. Overweight has reached epidemic proportions in the United States and that affects the health of the general population. So, it's right within the mission of CDC to do some recommendations on the subject of healthy weight levels.