World Health Organization, Obesity and overweight, on the Internet at http://www.who.int/mediacentre/factsheets/fs311/en/
Bureau of Labor Statistics, U.S. Department of Labor, Occupational Outlook Handbook, 2014-15 Edition, Fitness Trainers and Instructors, on the Internet at http://www.bls.gov/ooh/personal-care-and-service/fitness-trainers-and-instructors.htm