Let me tell you a super easy, low-fat, low-sugar, and insanely good way to make cupcakes:
1 box of cake mix (your choice)
1 small box of sugar free instant jello pudding mix (your choice, should somewhat fit with flavor of cake mix)
1 can of diet soda (I like to use cream soda or coke, but you can use whatever flavor you want!)
Stir all together, and bake according to box directions. These cupcakes are so moist and so awesome. Enjoy!