Re: >what happens if you aren't getting enough cals?
It's not a good thing...you'll most likely experience headaches, weakness, fatigue...It's not a way to loose weight, your body will try hard to maintain it's weight- so any cals you do consume will be stored as fat.
To safely loose weight you need to reduce calories, but not so much that you don't get enough. It's best to just subtract 500 calories from your normal intake to create a healthy deficient. If you don't know how many calories you consume, then just take a week to write down your totals for each day (without making any changes). Figure out the average number of cals you consume per day for a rough estimate average. Then subtract 500 from that number- that will equal how many cals you need to eat to loose weight. So, for example, if you find out that on average you consume 2,000 calories a day - then to loose weight you should be taking in no more than 1,500. If you just want to maintain your weight, don't go over 2,000.