A 2011 study notes that fast food consumption increased steadily in the United States from the 1970s to the time of the study. This same study examined adults in Michigan and found that their obesity rate rose steadily from 18 percent to 26 percent during the years 1995 to 2005. An additional study found that per capita calorie intake in the United States increased by 300 kilocalories from 1985 to 2002, as an article in Preventing Chronic Diseases reports.
A study of the dietary habits of adults in Michigan found that 80 percent of respondents went to fast food restaurants at least once per month, and 28 percent of people went more than twice each week. This study was unable to draw any conclusions correlating obesity with race, household income, education level or urbanicity. Its only correlation with obesity was fast food consumption. While 24 percent of respondents who ate fast food less than once per week were obese, 33 percent who ate fast food three times or more per week were obese, as a Preventing Chronic Diseases article notes.
A separate study examined obesity and proximity to fast food in children. The study looked at health data from 500,000 children in California and found that children with a fast food restaurant within 1/2 mile of their school were more likely to be obese than children who did not have one as close. The first group of students also consumed fewer fruits and vegetables, and they consumed more soda than their counterparts without fast food restaurants near their schools, according to an article in the American Journal of Public Health.