We interviewed Jeff Volek, PhD, RD, exercise and nutrition researcher, fitness expert, and one of the authors of the New Atkins for a New You.

We talked about the idea of trading your fat for muscle; of actually shifting the tissues around. To achieve this, two core tenets are employed; low carbohydrate eating to stimulate fat burning and resistance training to stimulate muscle growth. In brief, low carbohydrate diets consistently result in greater fat loss than any other diet program, and that resistance exercise results in greater muscle growth than any other exercise program.

Because you're breaking down one tissue and building another. That's a rather difficult physiological effect to achieve.

 The hypothesis of jeff's reserach was that restricting carbohydrates in combination with resistance training would promote the greatest fat loss while actually building muscle tissue. And that's exactly what he found. In fact the results exceeded my expectations. He had multiple subjects lose 15-20 pounds of fat while gaining 5-10 pounds of lean body mass.

What mechanism makes it possible for the body to build mass and lose mass at the same time? 

There's a concept called nutrient partitioning. Basically, it's the process of diverting nutrients away from fat storage and toward muscle building. Historically, it's been used in animal research. For example, in the agricultural context, you want to efficiently grow cattle and to make them leaner and make them have less fat while feeding them less food. If you can partition nutrients away from fat and toward lean muscle, you could simultaneously lose body fat and preserve and even build muscle. For most us, that's sort of the Holy Grail in terms of what they're trying to achieve with their body composition.

The idea that Jeff's team was interested in studying is, "How can we do this through normal lifestyle modification--through dietary means and exercise?" In fact, that's what his research has focused on for the last decade: Trying to optimize body composition--and health as well. 

One critical concept that's important is protein synthesis. In order to maintain your protein status in your body--mainly your skeletal muscle--you need to be in a positive protein balance. At all times you're constantly breaking down and synthesizing protein. So if you're breaking down protein at the same rate you're building protein, you'll be in protein balance.

But if you exercise and measure protein balance after you work out, you'll be in negative protein balance unless you eat some protein. So, in order to build muscle mass, we recommend eating a little protein after exercise.

There's also evidence that consuming protein before exercise has an even greater effect. The idea is that you eat protein to get some of the amino acids into your body and your bloodstream before exercise. When you work out, a good portion of your blood volume goes toward the active muscles that are engaged in the exercise, and more of the amino acids you ingested will be delivered to where you want them to go.

Based on several research studies that have investigated timing of nutrients with regards to workouts, we recommend that you eat high-quality protein before and after your workout. It doesn't take a lot of protein to get an effect on protein synthesis, so we're not providing an excess amount of protein. Ten to 20 grams seems to be the optimal amount.

High-quality  have all the essential amino acids--the ones your body doesn't make. Lower-quality protein sources generally come from plants and are lacking in one of the essential amino acids. Most proteins from animal sources, including dairy and most meats--beef, chicken and fish--all have the essential amino acids, so they're generally fairly high quality proteins.