Yulia is twenty-four years old. She has been fit and lean her whole life and recently has begun to put on an unhealthy amount of weight. She goes to her doctor because she is not eating any differently than she has before, yet she is now heavier. What will Yulia’s doctor most likely tell her?

A. Adults need fewer calories than kids and teens, so she needs to eat less.
B. Adults need more calories than kids and teens, so she needs to eat more.
C. Adults are heavier than kids and teens.
D. Adults need more exercise than kids and teens.