The number of obese people in the United States will increase from 99 million in 2008 to 164 million by 2030, and the number of obese people in the United Kingdom will increase from 15 million to 26 million, a new study predicts.

Already, the U.S. and U.K. obesity rates are the highest among the 34 member nations of the Organization for Economic Development and Cooperation (OECD), the study said.

The U.S. obesity rate will rise from 32 percent to about 50 percent for men, and from 35 percent to between 45 percent and 52 percent for women. The U.K. obesity rate will rise from 26 percent to between 41 percent and 48 percent for men, and from 26 percent to between 35 percent and 43 percent for women.

Read more about U.S. obese adults.