When i'm not fasting, I typically do Cardio w/HIIT + weights. While fasting 48 hr +, I'm wondering if its better to just do light cardio (e.g., swimming w/o sprints) or strength training? I'm thinking that my usual workout of both cardio and strength is out of the question but correct me if you think otherwise!
Doing your normal workout certainly isn't out of the question so long as you don't fall over - which is extremely unlikely in 48 hours if you're fit, hydrated and well adapted, but unless it's near the end of your fast you'll struggle a bit in the recovery. Great for fat loss, less good if your goal is muscle building. Most of the time adding in light cardio is a bonus whether or not you're fasting, but in my opinion it's worth occasionally doing your intense training in different conditions - at different points in and out of fasting. Not only is it more realistic but it gives you a chance of maximising all your energy pathways.
Y'know, I bit my tongue when you asked the question about craving sweets... You are 5'5" 100lbs, eating barely over 1000 calories a day, and working out for 2hrs+ daily. I don't think the question is what type of activity you should be doing during your 2-day fasts, but rather What - and more importantly - WHY you are doing this to yourself. These are questions only you can answer.
My paleo personal trainer has me do low intensity fasted workouts in the morning. 1 to 1.5 hours with HR at about 120-130 bpm. Fast walking, light cycling. I don't know about you but swimming always gets my heart rate up into the aerobic zone unless I'm just treading water or something. I'm about to do a depleted 1 hour walk right now! Best of luck to you!
I would steer towards lower intensity stuff that doesn't tap into the glycogen type burst activities... I personally (if working out fasted) will do non-aerobic stuff or low intensity things like walking... even some kettlebell lifts are suitable though obviously a lot of kettlebell work involves bursts