"Cavemen didn't do it" isn't a very good argument. Cavemen also didn't bathe, have supermarkets, modern medical care, electricity, a structured verbal language and mechanical means of transportation. Most neolithic things are better than their paleo counterparts - diet just isn't one of them.
Just eat real food. Try and make protein the centerpiece of each meal and build your dish around it. Pay attention to your hunger and try and eat slowly - the feeling of fullness lags behind by up to 20 minutes, so the faster you eat, the more you'll overeat due to this lagging fullness. Don't go adding fat to things that don't need added fat. Spooning butter all over your meal is no different than spooning sugar all over your meal. It's just empty calories. Use oil/butter as a cooking tool and a flavoring agent, not a significant source of calories. Throw in regular heaving lifting, some sprints and regular moderate cardio and you should get pretty darn close to where you want to be just by following these guidelines.
Don't put your trust in anyone on this forum, including me. You are the key to your own success.