*Geek Box: Measuring Appetite in Nutrition Research
To assess appetite and hunger in research there are three primary methodologies. The first is assessing “ad libitum” energy intake, i.e., allowing participants to consume as much energy from a presented meal as desired, and measuring how much is consumed. This generally requires researcher oversight in a clinical research facility.
The second is subjective appetite, hunger, and desire to eat measures using ‘visual analogue scales’ [VAS]. A VAS is a straight, horizontal line, commonly around 100mm [10cm] in length. The far left will generally represent the lowest end of the variable being measured, i.e., with fullness 0mm could be ‘not hungry at all’ while 100mm could be ‘extremely hungry’. Participants are asked to make a vertical line with a pen/pencil/marker across the horizontal measurement line, at a point which represents for them how they feel in response to that question. VAS can be used in a laboratory setting, but also used in a free-living context.
And the third is the measurement of appetite regulatory hormones, e.g., leptin secreted from adipose tissue, ghrelin secreted from the stomach, or GLP-1 secreted from the small intestine. Assessment of these biological markers requires blood sampling from participants.
Thus, which method is used will depend on the study design, the precise research question being addressed, and the resources [financial and technical] available to the research team. We discuss these concepts, as well as the concepts of “satiation” and “satiety”, in this Research Lecture.