The legs which include the gluteus maximus, quadriceps and gastrocnemius (calf muscle) are the largest muscle group in your body. The "glute" or butt is the largest of the three and is also very powerful. This muscle can easily atrophy over time if it is not used. As Americans we sit A LOT, and if you don't move it you will lose it. I just stood up to type because sitting around is not helping my glute! The quadriceps are the 4 huge muscles that comprise the front of your thigh… that’s why this muscle group is called the ‘QUADS’. These muscles also need to be used and active during the day by standing up, squatting and doing lunges. Finally the gastrocnemius or calf is the smallest muscles in the leg group and can be stubborn to build if you weren't born with great calf genetics. There are still things you can do to define this muscle like calf raises and isolation holds on your toes.
I would always recommend getting your nutrition in order first before starting a workout program because this will give you immediate results and your body will respond to healthy foods in such a way that it will reward you! You will feel better, have more energy, and be happier as a result of clean eating. Instead of focusing on calorie reduction, however, plan on eating plant-based whole foods that will fuel your body. If you have to eat some processed foods, always read the labels. If you don't recognize an ingredient your body won't either. When you are ready to add the fitness component be sure to do resistance training 3-4 times a week to build that all-important muscle and pay special attention to your legs. Resistance training is anything that is strength-building and uses barbells, weights, bands or your own body weight to increase muscle mass. Cardiovascular exercise is great but the calorie burn is over the minute your heart rate goes down. Muscle continues burning calories 24 hours a day, 7 days a week. P90X is one of my favorite programs because it really focuses on building muscle and can be done in your own home with minimal equipment. Plus the trainer, Tony Horton, is hysterical and will keep you pressing play throughout the 90-day program. If you're a girl building muscle should not scare you! Women do not have the testosterone levels necessary to pack on tons of mass. You would have to workout for years non-stop and you still wouldn't even get close to looking like a female Incredible Hulk.