i'm also 5'7''. firstly, your weight is a VERY healthy, great weight for someone that tall! and i eat literally almost 1,000 calories more than you a day and am losing weight... you can do this! you kill your metabolism if you restrict them forever.

You definitely need to eat more, esp when doing a program like Insanity where you burn crazy calories!

Here's where the problem is....say you eat 1400 calories a day but between your walking schedule and Insanity, you're burning 1000 calories. Not to mention what you're burning just doing regular daily activity. You're simply not getting enough calories so your body is hanging on to everything you're feeding it. This is where you stall out in your weight loss.

You need to eat enough to support all the activity your body is doing. And you don't want your deficit so large that your body continues to hang on to whatever you feed it.

I know it may seem completely backwards but it works. You just have to have faith and jump in with both feet!

Don't be afraid - your body needs that fuel! Honestly, with all that exercise (Insanity + Walking) even 1,700 sounds low. My guess is that you will probably still be netting at or below BMR (which is not recommended).

Have you figured out your TDEE ?