I used the Zone diet to lose my baby weight, and I am following TSP for maintenance. The Zone worked well for me to lose the weight. I lost 1-2#/wk most of the time while following it. My former WOE was low-fat/high carb, so the Zone was easier for me than going straight to low carb. I was already used to limiting fat, so that wasn't an issue for me. What was difficult was measuring
everything . There is an "eyeball" method you can use, but my eyeballs tend to overestimate portions.
The main reason I switched over to TSP is that is just sounded simpler, and the maintenance diet is very similar to the maintenance phase of the Zone diet. What most people don't realize is that the 40/30/30 proportions the Zone is famous for are what you use during weight loss, but when you are ready to maintain you start adding fat. But when I started adding fat, I realized I needed to take into account the carbs in fats like peanut butter, cashews and avocados.
Another thing I like better about TSP is the emphasis on whole foods. With the Zone, sweet potatoes and doughnuts are in the same category: unfavorable carbs. I didn't like that there wasn't a distinction between healthy carbs and unhealthy carbs. But of course you can decide for yourself only to eat whole foods on the Zone as well. Seems like a lot of people who follow the Zone spend a lot of energy developing Zone-balanced sweets, and I needed to get away from that. I still struggle with a sweet tooth that I like to feed with artificial sweeteners.
I still use the Zone guidelines to determine approximately how much protein I should have per day. I don't always measure my protein portion, but sometimes I do just to make sure I am getting enough protein. Hope this helps!
Jen