While the plank exercise helps to tone and strengthen your tummy muscles, it does not necessarily shrink the fat around your waist. In fact, the Dr. Oz Show website explains that eliminating tummy fat requires a combination of diet, cardiovascular exercise and tummy-toning exercises. A healthy diet and cardiovascular exercise help starve the fat cells — making them smaller. Tummy-toning exercises like planks and bridges help define the shape of your stomach muscles, making them long and lean. As your fat cells shrink and your tummy fat reduces, your toned stomach muscles become more evident underneath your skin.