Here's why:
Quaker Instant Oatmeal: Maple and Brown Sugar vs. Quaker Weight Control Instant Oatmeal: Maple and Brown Sugar. A package of the original variety is 43g, and has 160 calories, with 20 calories from fat; the Weight Control package is 45g, and has 160 calories with 25 calories from fat. So, where's the savings?
Both list "whole grain oats" as the first ingredient but the "classic" formula lists sugar second whereas the Weight Control formula lists whey protein isolate.
The ads claim that the oatmeal will keep you full longer and with protein powder as the second ingredient it will -- and if you add fruit to your bowl you'll have something that your body will consider a balanced meal. Just don't buy it thinking that "weight control" is equivalent to "low calorie."