Hi,
To lose weight, the work is 90% diet in my opinion. Are you eating a full paleo diet? I find myself its hard not to lose weight eating this way. If so, are you tracking your calories and eating 300-500 below maintenance? If you don't know what this means, look up your BMR (google helps) and you should find some good insight. I think many paleo folks maintain a healthy weight simply due to the lack of calorically dense options in our diet, but others might need to be a bit more tailored and put more attention on calorie counting.
What I am sure of is the answer isn't a pill ;-)