Ever wonder why your jeans keep getting tighter as you lift more weights? Most people's quads (at least the outside of section of the quad), here's a pic, are dominant in relation to the rest of the lower body musculature.
Unless you get your lazy butt to fire properly, then most of your squats and lunges are going to keep being a quad dominant exercise and your jeans are going to continue getting snugger right where you want them to slim down.
Here's the deal. Most people have lazy bums. No I didn't say most people ARE lazy bums but most people's bums are amnesic. They just don't know how to fire properly because we sit on them all day in a stretched out position. The neural pathways to many bums in this world are almost dead.
If you want to start evening out the imbalance of bum to quad strength, then I strongly suggest the following:
1) Start your lower body training with a butt activation exercise like a hip lift bum squeeze move, a standing superwoman or a side lying glute medius leg raise. If you don't know what these are, get your lazy butt into Urbanfitt.
2) If you're new to strength training, do as much unilateral leg work as possible (AKA one leg at a time). Single leg squats, split squats, walking lunges but only after you've felt your butt fire up as above.
3) Even after you've been training for a while, ensure you include an exercise that keeps the glute medius on fire. If you don't know what I mean, then again, get your lazy butt into see me.
4) Use your Jedi mind power to get your bum involved in your leg training. Focus on that flank steak and see if you can use your mind body connection to get it involved.
5) If you're a runner, take a look at the book "Born to Run". It'll show you how to change your running gate and technique to include more of your lower body muscles, not just your squads.