I haven't read all of the replies, and I know that the OP didn't really post originally about weight LOSS, but it seems to be a concern of many (me!). . .
I just have to tell you what is FINALLY working for me. I'm so excited that a friend told me about this program, and I can't say enough wonderful things about it (and no, I'm not selling it or anything). Honestly, it's the first thing I've tried (I've done WW, etc.) that I truly feel I can LIVE with . . .
www.dietpower.com
Check it out. . . But in a nutshell. . . It's a software program -- so you buy it ONCE (about $50). No monthly fees, no additional charges, no hidden costs, nothing. It begins by asking you all sorts of questions about yourself (weight, age, height, pregnant? breastfeeding? etc.). It then asks you what your goals are (losing weight? gaining weight? a more balanced diet? etc.). It then asks you what your target date for accomplishing these goals is. It then calculates, based on what you've told it, a typical metabolic rate for you. Then, YOU tell it every day what you eat (it lists THOUSANDS of foods, you can enter in your own recipes, store your favorites -- in the beginning this takes some time, but since a lot of what we eat is the same from day to day, after a week or two this goes pretty quickly). You also tell it abuot your exercise (again, it lists over 1000 activities, but you can also enter in your own) -- and if you're trying to lose weight, you get to eat every single calorie you burn -- talk about a motivation to exercise! Then, as you weigh yourself, the program MODIFIES ITSELF! If you're losing more quickly than expected, it gives you MORE calories. If you're losing more slowly than expected, it gives you FEWER calories. You HAVE to be honest with the program (and I highly suggest using a food scale and measuring cups), but if you are and you stick with it, you WILL reach your target goal by your target date. I just love it. If you use this program for weight loss, it's all about calories in, calories out. But it's the first thing I've found that feels relevant TO ME, because it modifies itself according to how my body is responding. It feels legitimate.
Also, it offers a ton of great "nutritional features". If you ask it, it will look at the foods you like (because you've been eating them) and say, for example, "you need more potassium, eat a banana today". It's awesome. And I just want to reiterate that this program doesn't have to be used as a weight-loss program. If you're just trying to maintain your weight, or balance your diet better, it can be used for this as well.
Anyways, if you're interested you should check it out. I don't mean to get on a soap box here, but I just wish I had known about this program a long time ago!
Oh, and I'll just add that exercising makes all the difference. Right now, on days that I don't exercise, to lose what I want to lose by my target date (if I were to give myself more time, I could eat more -- you get the idea), I can eat around 1350 calories a day. But if I exercise for about 45 minutes (using an elliptical and a treadclimber), then I usually get another 500 or so -- that's a lot of extra food! When I'm in a really good routine and going to they gym 5 times a week or so, I can see my metabolism boost up -- it had my eating almost 1700 calories on days that I DIDN'T exercise for a while! And I was still LOSING weight!
I'll really go now. But check it out!