Lecture 8 Flashcards
Portion size estimation in dietary assessment. The good, the bad and the ugly
what is the definition of portion size
the amount of food that is actually eaten within a defined eating episode
what are the dietary assessment steps
- measure food intake
- convert food to nutrients
- estimate absorbed intake of nutrients
- evaluate dietary adequacy
what are the sources of error for food and nutrient intakes
- memory / recall
- incorrect use of portion size tools
- quantification skills of respondent
- density factors
what are the cognitive processes in dietary assessment
- perception = amount in relation to aid
- conceptualisation = amount not present
- memory
what are the factors affecting accuracy of portion size estimation
- dietary assessment method
- type of food
- respondent characteristics
what are the characteristics of weight diet records
- exact grams
- largest respondent burden
- outside of home can be difficult
- reactivity
-before - after (amount consumed) - Missing ?
what are portion size estimation tools
24hr diet recall or diet record
estimate volumes (Beans, water and measuring cylinders)
what are the characteristics of 24hr diet recall or diet record
-household measures
- standard measure units
- known packaging size
- visual aids
- categorical size estimations (small, medium and large)
- food models
- hands
what are the possible settings of diet record methods
home versus research clinics / schools or workplaces
what are the ways that diet recall methods can be administrated
interviewer administrated or self administrated
characteristics of computer based self administered recalls
- photos
- common standard measures
- packaging sizes
- shapes / dimensions
what is the recipe dilemma
- ingredients
- quantity
- before cooking : can change after cooking
- yield after cooking
- % consumed by participant
- part eaten
why is pre portioned food great for dietary assessment
easy way of knowing how much someone consumes, , however portion sizes can be inaccurate when comparing to what the person actually consumed
what is the flat slope phenomenon
- large portions : underestimated
- small portions : overestimated
what are examples of amorphous food and why are they an issue in dietary assessment
more difficult to estimate than single unit food
- example : pasta, rice, mashed potato
what is commonly found with pack size and dietary assessment
consumers estimates large portion sizes if food is from a large size pack
NZ FOOD COMPOSITION DATABASE: common standard measures
1 cup=250ml
1 tablespoon=15ml
1 teaspoon= 5ml
three factors of respondent characteristics
- ethnicity and culture
- literacy and numeracy
- age
how is ethnicity and culture affect respondent characteristics
- shared dishes
- different utensils
- eat with hands
litracy and numeracy
Seld administered versus interviewer
Age
-Older adults memory
-Cognitive development children
what are the challenges for research with children
- eat smaller amounts
- varied cognitive ability
- served by others
- more left overs
- food literacy
- proxy respondent
it is not advisable to do recalls for children under the age of
10
what are the challenges with research of children under 10 years
- volume can remain the same if object changes dimension
- size of object depends on eye distance
- reverse action-liquid in original bottle
characteristics of 24hr recall in teens and children
- neutral and non judgemental
- siblings and parents
- table ideal (50%)
- wide variety in sizes of household measures
what are active approaches to dietary assessment
remote food photography and digital food records
how does remote food photography and digital food records work
foods photographed before and after eating on a 45 degree angle
images transferred wirelessly in real time
what is the analysis of remote food photography and digital food records
- manual image analysis
- automated image analysis
what is passive approach to dietary assessment
automated cameras
what are the strengths to automated cameras
- lower respondent burden ?
- not memory reliant
- less reliant on food literacy
- less subjective error
- measure contextual factors
what are the limitations
- privacy, ethical considerations
- software dependent
- currently labour intensive
- image quality
- quantification of food
future Directions: technology
-Reactivity
-Complement current methods
-Automate
-Equipment and software accessible
