While all bodies are different and body fat percentage may vary depending on several factors, a study published in the American Journal of Clinical Nutrition determined optimal body fat percentage ranges at a given age. Women Age 20-39: 21%-32% Age 40-59: 23%-33% Age 60-79: 24%-35% Men Age 20-39: 8%-19% Age 40-59: 11%-21% Age 60-79: 13%-24%