Now about the limitations of the research: The small number of studies available for review makes the conclusions "tentative," the researchers wrote. Kids in this age range are growing, so it's more difficult to assess their weight gain than the weight increases of fully mature adults, though the researchers did note the use of a complicated formula to control for that in some cases. In Japan, where there was no weight gain seen, the summer break is only about 40 days long. And the research Franckle reviewed was conducted in different ways; some of it looked at anti-obesity programs that failed to provide a clean association between summer and weight gain.
Nevertheless, Franckle and her team suggested that poor kids be given even wider access to programs that will promote outdoor exercise, including opening up schools during the summer. Summer nutrition programs should also be expanded, she said.