Abdominal muscles consist of three layers. The very deepest layer is the transversus abdominis, which acts as the body's girdle, providing support and stability and plays a critical role in exhalation. Next is the rectus abdominis, which flexes the spine. Closest to the surface are the internal and external obliques, which turn the trunk and provide the body with rotation and lateral movement.
Building muscle and burning fat at the same time is the holy grail of bodybuilding but many people believe that it’s impossible. Here’s how it goes. Experienced bodybuilders first bulk then cut. Bulking is the period where they eat more calories than they burn (caloric surplus) in order to pack on muscle mass. Cutting is the period where they eat fewer calories than they burn (caloric deficit) in order to burn off the fat they inevitably gained during the bulk. The remaining muscle after bulking and cutting is their lean muscle gain.
“For me, getting a six-pack was about paying attention to what I was eating and lifting heavy weights at CrossFit. I do have a semi-strict diet, and I loosely count macros (focusing on daily carbs, protein, and fat intake rather than blindly counting calories) to stay balanced and on track. It sounds like a lot of work, but it really isn’t. Eventually, it just became a part of my lifestyle, and it’s something I enjoy doing. I even started a custom meal-plan business based on macros because I had such great results!” —Tina Haupert, @carrotsncake