The gluteus maximus -- better known as your butt -- is pure muscle. The only way to make your butt bigger and keep thin is to build up that muscle with exercise. Strength-training exercises targeting the glutes can enhance the size, shape and form of your derriere. These exercises can also tighten and tone the butt, lifting the muscle to make it appear bigger without an excess of fatty covering.
Warm up for five to 10 minutes with jogging or marching in place. Follow your warmup with a gluteal stretching exercise. Lie on the floor, and cross your right leg over the left one. Your right ankle should balance on your left knee. Reach in between your legs, and grasp the back of your left thigh just above the knee. Gently pull the thigh toward your chest until you feel the stretch in your butt. Repeat this on the other side.
Complete 30 minutes of aerobic activity daily to stay skinny. Swimming, running or even dancing can increase your heart rate and help you burn excess calories to maintain your weight.
Add exercises to tone the bottom at least twice weekly. If you are a beginner, start with a wall squat. Flatten your back against a wall, and push your feet 18 inches in front of you. Slowly drop your seat toward the floor until your knees are bent at a 90 degree angle, or as tolerated. Repeat 12 times.
Lunge your way to a firmer, bigger buttocks. Take an exaggerated step forward with your left leg, and keep your back leg straight. Bend your left knee until your thigh is parallel with the floor. Take care not to bend your knee over your toes; keep it aligned with your ankle. Do 12 repetitions, then switch to the other side.
Take the steps whenever possible or use a stepping block to exercise the butt. The step-up exercise uses your gluteal muscle. You can also hold dumbbells in your hands to enhance the exercise.
Eat enough protein to build muscle and a bigger butt. Aim for 2 grams of protein daily for each kilogram of your weight; a kilogram is about 2.2 pounds. Choose lean proteins such as legumes, skinless poultry and fish.