Our bodies can be placed under 3 basic categories (and further sub-categories) based on the size and shape of it. Knowing ones’ body composition is also a great way to understand lean body mass and body fat. And if your body lies within the range of healthy body-composition, then you’re sorted.
A good body composition is directly related to what you demand from your body—say, if you’re an athlete, then on the percentage scale of body-fat, you’d want to be on the lower side. Though of course your somatotype has to be considered, and it’s not always that being on the lower end is an ideal situation.
Women’s bodies contain more fat than men’s for biological reasons like developing reproductive tissues and better ingestion of vitamins, etc. Thus the range for optimal body-fat, in case of women is 14%-30% and for men, 6%-25%. So if your body-fat is near the lower side while your level of fitness is that of an athlete or general fitness then losing fat won’t benefit your performance. Perhaps you’ll get sick in the process.