A person’s body mass index (BMI) is a common method for measuring obesity, a proxy for diet and exercise. The standard threshold for obesity is defined as greater than or equal to 30kg/m2 (weight in kilograms divided by height in meters squared).
Daily food logs, recall questionnaires, and surveys are often used to measure the amount and consumption of food. The only option feasible at the population level are survey questions as they require less time and person-power to record the data accurately. Small studies may also use technical methods to measure the exact amount of nutrients consumed.
Researchers have used a variety of strategies to measure the food environment ranging from geographic information systems to observational assessments. Studies of access to healthy foods generally look at access in terms of distance, income, and transportation. Foods such as fruits and vegetables are commonly available at grocery stores, supermarkets and farmers markets but not in convenience or small grocery stores where a large percentage of Americans purchase their food. [1,2]
Measures of physical activity are usually taken from surveys for which a person self-reports the amount of time they spend participating in various activities such as aerobics, walking, biking, swimming, or jogging. Other measures of physical activity include using pedometers, accelerometers, or target heart rate measurements. However, these are not feasible on the population level across counties.
Researchers have used several methods to capture important aspects of the environment that affect physical fitness and activity levels. One approach involves sending teams of auditors to communities to measure built environment factors using specific criteria and tools. To date, this method shows strong promise for collecting reliable and objective data; however, many communities do not have detailed GIS information available and the staff and resources needed to collect and analyze such data are expensive.
 Wrigley N, Warm D, Margetts B, Whelan A. Assessing the impact of improved retail access on diet in a ‘food desert’: A preliminary report. Urban Studies. 2002;39.11:2061-2082.
 Hallett LF, McDermott D. Quantifying the extent and cost of food deserts in Lawrence, Kansas, USA. Applied Geography. 2011;31:1210-1215.
 Brownson R, Hoehner C, Day K, Forsyth A, Sallis J. Measuring the built environment for physical activity: State of science. Am J Prev Med. 2009;36.4:99-123.