I've lost almost 100 lbs just by calorie counting on MFP. It also initially motivated me to walk a few miles a day to earn an extra couple hundred calories. For me it was sustainable because I can stick to it forever, eating whatever food group I want to, just in moderation. And once I got used to logging, I could do it in just a couple minutes by saving meals and regular foods. Kudos to you ladies who can do low carb, low fat, etc.. I could never give up my bread, pasta, ice cream, etc and stick to it!