Disability as defined by the ADA is a physical or mental impairment that substantially limits one or more major life activities. For obesity to be considered a disability it must have a physiological cause. The American Medical Association, The World Health Organization, The Food and Drug Administration, and the National Institutes of Health recognize obesity as a disease, not a disability.  Obesity was always struck down as a disability in the past, but there have been mixed results in recent court cases. You're right, this will be fun.