An assessment of nutritional status may include a comprehensive evaluation consisting of dietary analysis, physical examination, and anthropometric and laboratory assessments. Dietary analysis can measure total energy, specific amounts of nutrients, and diversity. Food frequency questionnaires assess energy or nutrient intake by determining how frequently an individual consumes a limited checklist of foods that are major sources of nutrients or of a particular dietary component in question. Unlike the 24-hour recall and the food records, which assess recent intake for a short period, the dietary history is used to assess an individual's usual dietary intake over an extended period of time, usually a month to a year. Common examples of anthropometric measurements include health, weight, and body size. Nutritional status can be evaluated using a clinical assessment. Direct calorimetry involves the measurement of heat produced during metabolism. The rationale behind indirect calorimetry is that virtually all bioenergetic processes are oxygen dependent. Pedometers count the motion by responding to vertical acceleration.