Keep Your Muscles Healthy. One of the many misconceptions about a healthy lifestyle is that you should be skinny. Nothing could be further from the truth! Too thin can be just as unhealthy as too heavy. And, low-cal is the fastest way to destroy your body’s ability to maintain healthy skin, muscles, joints, & more. The trick is to choose food with care. And, to mix in enough protein & unrefined carbohydrates so you can build muscle & lean body mass.