I am over weight (1.85m/6 ft 1" and 105 kgs/231 oz). I started working out 8 months ago and I have lost 25kgs/55 pounds. Over the last 2 months I am focusing on muscle exercises as much as cardio and aerobic ones. My question is this: What exercises would you suggest for the upper bottom/seat/buttocks area. I am doing squats. But apart from that, are there any additional exercises that can help tone that area?
Back squats are a great start, but I would also suggest doing front squats because it's feasible to go much deeper with them, and going very deep (ass to calves) with a front squat uses your hamstrings more than the back squat to just below parallel. The deadlift works your lower back more, so by adding both front squats and deadlifts you're approaching the butt area from both sides.
Also, the deadlift and front squat are quite good for a lot of other muscles, so you'll be ending up in better shape overall. There might be some isolation exercises you could do, but I prefer to see what benefits can be achieved from compound exercises, and only resort to isolation exercises if absolutely necessary - I like to spend as little time working out as possible.
If you're doing multiple work sets of back squats now, I would recommend against suddenly throwing on an equal number of sets for the front squat and the deadlift. If, for example, you're doing 4 sets now, cut it down to 2, so you're doing 6 sets total for the 3 lifts.
The website ExRx (http://www.exrx.net) has a long list of exercises and descriptions, which you can sort by muscle group. Here's there list of exercises that work the butt (gluteus maximus): http://exrx.net/Lists/ExList/HipsWt.html#anchor169231
Doing anything on that list should help work that area.
Squats, lunges, and deadlifts are all great at targeting the buttock (if done right).
"Doing them right" entails:
1) Proper warmup and activation
2) Proper form
Most people have "sleepy butts" (from sitting all day) and need to activate their glutes before they can use them. If they don't do this and lack the proper activation, other muscles (like hamstrings and quads) will simply take over the movement. Before we do glute activation (such as this), however, we need loosen up our hips (with an exercise such as this)
With proper activation, your form should be immediately cleaned up. But if you have any doubt, I suggest you check out Bret Contrera's videos.
When you ask about "toning" one area, it sounds to me like you are really talking about losing fat from that one area. If that is the case, the answer is that you cannot as stated by the answers to this question: Is working out localized muscle going to help burn fat in that area more than building up overall muscle mass?
So the best you can do is to continue to lose weight and your body will decide which places it will remove the fat from. Sorry for the bad news...