Here's a major issue that many "gurus don't mention. Body weight and fat distribution has a very definite genetic profile. If you are mesomorphic, your fat distribution will be different from someone who is endomorphic. Mesomorphs can burn fat and build muscle quickly. With proper diet and exercise, they can achieve the standard athletic build.
Endomorphs have much slower metabolism and their fat distribution gives them the round or pear shape. It is much harder to maintain the athletic look. This is why endomorphs blow up far more easily when they practice yo-yo dieting. The good news is that the endomorph body type can build muscle easily, so they can increase their metabolism but should not concern themselves with trying to look skinny. The point is to be healthy and fit.
Read the Article at HuffingtonPost