Consistency is key when it comes to training to change your butt and waist.
Digital Vision/Photodisc/Getty Images
There are a wide range of exercises that will tone the butt and slim down the waist. Your core muscles provide a lot of stability for most exercises -- so your waist is being effected all the time -- but the exercises that will specifically hit the waist are different to those that will target your butt. It's also important to focus on doing consistent and challenging workouts over a long period of time in order to get the best results.
Do The Deadlift
The deadlift is one of the most effective exercises when it comes to toning your butt. To perform a deadlift correctly with a barbell, start with the barbell on the floor, then place your feet underneath it, so the bar is over the arch of each foot. Crouch down to the bar, keeping your back straight, then grip it as tightly as you can with your hands about shoulder-width apart. Pull the bar off the floor by straightening your legs, then push your hips forward and squeeze your glutes at the top of the movement, pulling your shoulders back if they are rolling forward at all.
You've Got To Squat
Squats are also highly effective for toning the butt. While they also hit your quadriceps and hamstrings, squats will help tone and strengthen your glutes significantly. To do a proper squat, load the barbell at chest height, then unrack it onto your upper back. Keeping your core engaged, bend at the knees until your thighs are just past parallel to the floor -- be careful not to let your knees travel out past your toes. Pause a moment at the bottom of the movement, then extend your legs back to the start position and clench your glutes at the top.
Sprinting is a very effective form of exercise, both for toning the butt and for slimming the waist. A form of HIIT -- high intensity interval training -- sprinting requires massive force to be generated by the glutes in order to propel you forward quickly. It also requires a huge amount of stabilization and engagement from all your core muscles. In fact, the "International Journal of Obesity" found that this style of training was significantly more effective than normal "steady-state" cardio for burning belly fat and improving lean muscle definition.
It's Crunch Time
Crunches -- and their many variations -- are the most effective exercises to slim down the waist. To target the rectus abdominus -- the "six-pack" muscle, use regular forward crunches. Twisting crunches target the external obliques, while decline crunches target the rectus abdominus, external obliques and internal obliques. A word of warning on regular crunches, though: they can put a lot of pressure on the lower back, and when overused can cause the rectus abdominus to thicken -- and this causes a bulkier waist than a slimmer one, so use them in smaller proportion than the other variations.
Work The Plank
In order to really tighten the stomach muscles and slim the entire waist area, the plank is a must-do exercise. There are two basic plank variations that can be used to target different areas of the waist. The standard forward plank will specifically tighten and flatten the rectus abdominis. If the standard plank is too easy to make a difference to your waist, make it more difficult by rocking forward and back on your forearms. Side planks will tighten your external obliques to slim down any "muffin top" there -- and to increase the difficulty, extend your top arm toward the ceiling for the duration of the movement.