All exchange plans are variations on the same theme - you get a certain number of servings (and the servings are fairly similar in calorie count for each group - so all fruit servings are going to be about 6o calories - all dairy servings are going to be about 90 calories....). Most exchange plans are based on a plan developed for diabetics in the 1950's, and the exchanges themselves haven't changed much in 50 years, so almost all exchange plan recipes are interchangeable -for example, I have cookbooks with publication dates from 1960 to the present written or published by the American Diabetes Association, Weight Watcher's (before they made the switch to points), Richard Simmons, and Joanne Lund (Healthy Exchanges).
I found a lower carb exchange plan on the hillbillyhousewife and adapted it (when I was on WW's exchange plan, I liked the "flexible" exchanges they included). I get 2 fruit exchanges, 2 starch exchanges, 10 protein exchanges, 4 fat exchanges, 2 dairy exchanges, 4 vegetable exchanges and 8 flexible exchanges that I don't have to use, but if I do I can use them on fruit, starch, protein or dairy exchanges).
If I don't eat any of my optional exchanges, my calorie count is about 1400 to 1500 calories. If I eat all of my allowed exchanges, the calories are abougt 1900 -2000. I average around 1800 calories, most days.
Just like calorie counting, most foods can be categorized into exchanges. Not always perfectly, but if you know the fiber, fat, calorie, protein, and carbohydrate count, you can do the calculations yourself or look them up in a book or online resource. I use diabetic resource sites, the hillbilly housewife set and a book I bought from amazon called "exchanges for all occasions."
I try to eat mostly whole foods, not only because they're better choices, but because they're easiest to count. A fruit for example is one medium orange, a half of a large apple, half of most bananas.....
Because all of the foods in any category have a pretty similar calorie count, most exchange plans are identified by their calorie count. Different exchange plans may distribute the calories slightly differently -
This link goes to three different basic plans for 4 different calorie levels. You'll see my choices are a little different, because I made room for optional exchanges, for flexibility. I did well on Weight Watcher's when they were an exchange plan, and I really liked the idea of having some flexibility. So I patterned my optional flexible exchanges after what I remember of WW's old program.
http://healthy.hillbillyhousewife.com/foodplans.htm