The incidence of fair and serious obesity classified by Dr. Nagamine's skinfold thickness method was 13%, 26%, 22% in the mentally retarded boys 9 to 11 years of age, and 22%, 35%, 24% in the girls 12 to 14 years of age, respectively. The total incidence of slight, fair and serious obesity was 34%, 46%, 39%, 38%, 31%, 31%, 12%, 11% in the mentally retarded boys 9 to 16 years of age, and 20%, 11%, 20%, 9%, 18%, 8%, 8%, 12% in the control boys aged 9 to 16 years, respectively. In the 9 to 16-year-old girls, the total incidence of obesity was 11%, 28%, 28%, 47%, 48%, 40%, 20%, 23% in the mentally retarded groups, and 4%, 9%, 0%, 23%, 13%, 29%, 13%, 2% in the control groups, respectively.
The performance of motor ability and physical fitness in the mentally retarded children tends to be inferior to that in the mentally non-retarded children. An autistic child with seriously mental retardation succeeded in mastering the hoop skipping (a kind of rope skipping) devised by Mr. Takahata. The learning process of the hoop skipping technique was summarized in detail with Mr. Takahata's book. The guidance method of the hoop skipping devised by Mr. Takahata was introduced at full length. The hoop skipping exercise can put on the brakes to th serious degree of obesity, but may not solve the obesity problem completely. Other autistic child with seriously mental retardation succeeded in reducing the seriously obese weight only for one year. His cause and process of obesity conquest was analyzed from a viewpoint of food control and daily physical exercise and family-school mutual obese backup system.