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HNFE 3034 Lab Final Exam Study Guide

Terms in this set (86)

- 24-hour dietary recall: Trained interviewer obtains information on all items consumed in the past 24 hours; might be asked to being with the first food/beverage consumed after waking up and go through meal by meal (most accurate)
o Advantages:
§ Low participant burden and can be done in ~20 minutes
§ Participants are not likely to alter their usual food intake, since the recalls are generally done unannounced
§ Minimal problems with relying on memory, since the time interval is brief
§ Participants are generally willing to respond to the interviewer; they are not likely to refuse to give information
§ Can be done in-person or over the phone
§ Considered the best method of dietary assessment (most accurate), when done according to recommended methods - multiple pass method, three recalls are done to capture usual intake
o Disadvantages:
§ Does rely some on memory, although less than food frequency
§ One recall alone is not adequate to determine typically intake
§ Under-reporting and sometimes over-reporting errors can occur
§ Diet can vary across seasons of the year or during vacations
- Food intake records/diaries: participants record all foods and beverages consumed for several consecutive days - usually 3 to 4 days; days should include weekend and weekdays; should be very detailed with brands and portion sizes
o Advantages:
§ Does not rely on memory
§ Can serve as a self-monitoring tool for people trying to improve their dietary habits; helps to promote diet adherence
§ For researchers and practitioners, it can be simpler logistically than multiple 24-hour recalls, since the person does not need to be contacted multiple times to obtain recalls
o Disadvantages:
§ Individuals must be literate, motivates, and trained in the procedure
§ More burdensome for individuals to do than other methods
§ It is not realistic to use this method for larger population studies
§ Provides information on recent diet, not past history of food consumed
§ People may alter their eating habits while recording their intake; under-reporting
- Food Frequency Questionnaires: a varying length of questions about an individuals' food intake of all different nutrients (least accurate)
o Advantages:
§ Simple to administer; can be self-administered
§ Can be modified or expanded to adapt to changes in the food supply of for different populations
§ Cost-effective; used in very large samples; dietary intake over longer periods of time
o Disadvantages:
§ Less precise - individual must choose from a list of foods and portion sizes, which might not be consistent with what they usually consume
§ Must first be validated in the population interest
§ Must be checked for completeness after they are filled out
§ Often will underestimate calorie intake and overestimate micronutrient intake
- Hydrostatic weighing: 2-compartment model
o Based on the Archimedes principle that the volume of a person is equal to the water displaced by that person
o Pro: very accurate
o Con: assumes a constant density of lean and fat tissue
- Bod-pod: 2-compartment model
o Body volume measured using air displacement; larger the body the more air will be displaced
o Pro: normally more acceptable to study subjects than underwater weighing and avoids the breathing maneuvers associated with residual volume measurement
o Con: expensive and assumes a constant density of lean and fat tissue
- DEXA: 3-compartment model
o Measures % bone, FFM and FM with two x-ray energies with low exposure to radiation and each type of tissue has an attenuation constant so % of each tissue is determined
o Pro: very accurate
o Con: the soft tissue in bone pixels must be estimated from surrounding soft tissue pixels and therefore there is some extrapolation; assumes a constant density of lean to fat tissue
- BIA: 2-compartment model
o The impedance of the current is related to the amount of body water, body density, FFM, and % body fat
o Pros: affordable and easy to use method for assessing body composition in large population settings
o Cons: the stand on analyzer is that it determines body composition in the lower half of the body and extrapolates the % body fat for the entire body; dehydration overestimates % body fat and over-hydration underestimates % body fat; over-predict body fat in lean and athletic populations and under-predict body fat in obese populations