How to tone up my arms and stomach? after losing (a lot of weight)?

I'm 276. I use to be 293 a month ago. I'm currently on a workout program called insanity and I'm watching what I'm eating. I'm on a 1200 cal diet. Nothing over. I have not been starving myself.. just pushing real hard and i managed to lose 17 pounds. I don't want my arms becoming flabby and sloppy looking. What are exercises to tone up my arms and te rest of my body? being that i'm losing weight so fast. Thanks in advance.