I've stumbled upon an online weight loss tool I really like, and some of your patients might like it, too.
It's "Calorie Count Plus", a food and activity tracker on About.com. With minimum effort on the user's part, the site keeps track of the daily calories you burn as well as those you consume, and will chart the results over time. (remember, this strategy works: an August study in the American Journal of Preventive Medicine found keeping a food diary can double the chances of losing weight.)
The site also has a feature where you can look up the calorie and nutrition information of the foods you eat, and it will give you a nutrition analysis and grade (A-F) according to how balanced your diet is. You can also keep a journal, participate in message boards and make "friends" through the site, if you choose.
My favorite feature: The "calories burned" counter resets to zero at midnight and updates throughout the day, using a projection based on your weight and height, plus any activities you tell it to include. It's kind of fun (and motivating) to watch that number climb.
Heck, I burned 10 calories just sitting here writing this blog post.