Dietary assessment and physical activity measurements toolkit

Glossary of terms

 

  • Basal Metabolic Rate (BMR) – is the minimal rate of energy expenditure compatible with life. It is measured in the supine position when the individual is in a state of rest (non-sleeping), mental relaxation, fasted, and in a neutrally temperate environment. It is the largest component of total energy expenditure (TEE), typically 60-75% when measured over 24 hours. Sleeping Metabolic Rate (SMR) and Resting Metabolic Rate (RMR) are marginally different from BMR but are sometimes used in place of BMR which requires strict conditions.
  • Biomarkers – are used in dietary assessment to validate reported food intake and are generally components of body fluids or tissues that have a strong relationship with dietary intakes. For example, nutrient levels in serum or plasma and urine can be used to reflect recent dietary intake. 
  • (Dietary) Coding – is the method of matching food items reported in a diet record (e.g. food diary) with a food code on an electronic database.
  • Doubly Labelled Water (DLW) – A method used to measure the average total energy expenditure of free-living individuals over several days (usually 10 to 14), based on the disappearance of a dose of water enriched with the stable isotopes 2H and 18O. It is considered the ‘gold standard’ measure of energy expenditure but its expense limits its use in research.
  • Food composition database - provide detailed information on the nutritional composition of foods – energy, macronutrients (energy, protein, carbohydrate) and micronutrients (vitamins and minerals). Nutrient values are usually expressed in terms of the nutrient content of the edible portion of the food per 100g. Examples of databases include USDA and McCance and Widdowson’s The Composition of Foods.
  • Food composition tables – are printed versions of food composition databases.
  • Goldberg cut-off – is used to identify dietary underreporting and is based on the principle that an individual of a given age, sex and body weight requires a minimum energy intake. Reported energy intakes below this level are considered to be an implausible representation of habitual intake. The cut-offs can be used at both the individual and group levels.
  • PAL (Physical Activity Level) – Total energy expenditure for 24 hours expressed as a multiple of BMR, and calculated as TEE/BMR for 24 hours. In adult men and non-pregnant, non-lactating women, BMR times PAL is equal to TEE or the daily energy requirement.
  • Total energy expenditure (TEE) – is the energy spent, on average, in a 24-hour period by an individual or a group of individuals. TEE consists of three components; Basal Metabolic Rate (BMR) (typically 60-75% of TEE), the thermic effect of food (10%), and energy expenditure due to physical activity (the most variable between individuals, typically 15-30% of TEE). 


Dietary assessment methods
Prospective

  • Weighed food diary (or record) – is a detailed prospective dietary assessment method. An individual undertaking a weighed food diary is instructed to weigh all foods and beverages consumed during a specified time period, generally 4-7 days. He/she records details of food and drink eaten at the time of consumption. It is considered the most precise method available for estimating usual food and nutrient intakes of individuals but the heavy respondent burden is thought to lead to considerable underreporting (Livingstone 1990; Livingstone 1992).
  • Estimated (unweighed) food diary – is a detailed prospective dietary assessment method. Respondents record details of food and beverage intake at the time of consumption in household measures (e.g. 2 teaspoons of jam etc) or natural unit sizes (e.g. 1 slice of medium cut bread) for a specific period of time, generally 4-7 days. Photographs are often provided to assist portion size estimation.
  • Dietary checklist – a prospective method that combines elements of a food frequency questionnaire (as it is based on a pre-printed food list) and an estimated food diary. Respondents refer to the food list and the specified serving size (e.g. slices, teaspoons) and tick the box the appropriate number of times corresponding to the quantity eaten.

 
Retrospective

  • Food frequency questionnaire (FFQ) – The FFQ aims to assess the frequency with which food items or specific food groups are consumed over a particular time period (e.g. 6 months or a year). In its simplest form the FFQ consists of a list of foods and a multiple response grid which respondents use to indicate how often they eat a particular food item.
  • Dietary history – attempts to estimate usual food intake of individuals over a relatively long period of time e.g. 6 months to a year. Traditionally, the method consists of three parts: a structured interview consisting of questions about habitual intake of foods, a ‘cross check’ questionnaire to clarify information about usual intake, and a 3-day food diary. The food diary is sometimes omitted or replaced by a 24-hour recall.  
  • Recalls – a retrospective method of dietary assessment in which a subject is asked by a trained interviewer to recall their exact food intake, typically during the previous 24-hour period or preceding day. Repeat 24-hour recalls can be carried out to estimate multiple days of intake, and if conducted during different seasons of the year, provide an estimate of food intake over a longer time frame.

 

Web design by Studio 24