METHODS OF MEASURING FOOD SECURITY

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Food security can be measured using five (5) methods:

i. House hold income and expenditure surveys

ii. The food and Agricultural Organisation (FAO) method of estimating calories available per capita at the national level.

iii. Individual‟s dietary intake

iv. Experience-based food security measurement scales v. Anthropometry

i. Household income and expenditure surveys

Household income and expenditure surveys method is an interview method.

Respondents are interviewed in their households. Respondents provide information on the amount of money that they spend on food and other necessities. Different time reference periods have been used including the week(s) or month(s) preceding the survey. To use the household income and expenditure survey method, the following data are needed:

a. quantity of food bought (or expenditures) and costs associated with different foods consumed within and outside the house.

b. foods received by any household member as either a gift or as payment for work, goods or services.

c. foods grown for consumption by household members. This method estimates calories consumed on average per household member per day, making it essential to have access to culturally appropriate and valid food composition tables.

ii. The FAO method

FAO method estimates calories per capita at the country level using Food Balance Sheets

and energy intake variance data derived from household income and expenditure surveys.

The following information is needed by countries to be able to apply the FAO method:

a. total calories available in year of interest

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b. number of people living in country in year of interest

c. coefficient of variation of caloric intake to generate the energy intake distribution curve

d. cut-off point to estimate the proportion of the population falling under the minimum per capita average caloric requirement.

Advantages of the FAO method

The FAO method has the following advantages:

i. almost all countries generate the data needed and estimate their daily per capita caloric availability

ii. estimates are frequently updated thus allowing the national, regional, and global food insecurity trends across time to be examined and compared iii. the method is inexpensive.

Disadvantages of the FAO method

The FAO method has the following advantages:

i. dietary quality is not taken into account

ii. the national average per capita caloric intake does not allow for understanding the intra country caloric distribution as a function of household characteristics.

iii. method assumes that caloric consumption above minimum caloric threshold indicates food security, when in fact obesity has become a problem among the poor with excessive caloric consumption being associated with mild to moderate levels of food insecurity.

iv. high degree of measurement error in numerator (balance sheets provide data on the amount of calories available but not necessarily consumed) and denominator (i.e., number of inhabitants living in the country in the year of origin). Overall, the origin of data used by countries is sometimes difficult to understand and of questionable validity, and there is little standardization and

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v. establishing an average per capita caloric requirement cut-off point has several conceptual weaknesses as in reality it is a function of physical activity levels, gender and age, among other factors.

iii. Individual’s dietary intake

An individual‟s dietary intake can be measured using different methods such as : a. 24-hour dietary recall

b. food frequency questionnaires

c. food records kept by individuals or by an observer.

All dietary intake methods need to make use of a reference time frame. The 24-hour dietary recall and food frequency questionnaire rely on the memory of participants while food records rely on the recording of foods, as they are consumed, by the study participant, a proxy or an observer (Pérez-Escamilla and Segall-Corrêa, 2008).

Portion size estimations can rely on assisted memory (e.g. using food models) or foods can actually be weighted before and right after consumption. These portion size estimations are needed to estimate food group counts as well as nutrient intakes, the latter provided that culturally appropriate and valid food composition data bases are available. Lastly, to interpret the nutrient intake findings it is important to have cut-off points for determining the proportion of the sample or population at risk of deficiencies for different nutrients (Pérez-Escamilla and Segall-Corrêa, 2008).

Advantages of Individual’s dietary intake

a. It measures food consumption directly and not only food availability

b. it addresses both dietary quality (macro and micronutrients) and caloric intakes at the individual level

c. it allows for mapping from the local to the national level, and the determinants and consequences of food insecurity at the individual level can be examined; this is important for understanding, for example, intra-household food consumption patterns and how it is influencedby gender

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d. different dietary intake methods can be used to understand recent (e.g., 24-hour

recall) vs. longer term dietary intake patterns (e.g. food frequency questionnaires).

Disadvantages of Individual’s dietary intake

a. the 24-hour recall and the food frequency questionnaire rely heavily upon the memory of respondents and this might lead to measurement error. This is because respondents are asked to recall what they ate the day before, method of preparation of different meals (e.g. boiling, frying, roasting), spices and other ingredients used and to provide the recipes followed with mixed dishes and the quantity of food consumed. In all these, a high measurement error might be encountered especially if untrained interviewers are used. In addition, 24-hour recalls need to be applied in different occasions to the same individuals to be able to have a reasonable estimate of their usual food and nutrient intakes. Single 24-hour recalls cannot meet this need as the intra-subject day-to-day variability in food (and nutrient) intake is very high. In sum, the first major disadvantage of the 24-hour recall and other dietary intake methods is a very high level of measurement error (Pérez-Escamilla and Segall-Corrêa, 2008).

b. Is expensive especially if is a national survey. Each 24-hour recall takes at least 20 to 30 minutes to apply (depending on the amount of food consumed by the respondent).

c. a high level of training and skill is required to convert food intake into nutrient intakes.

iv. Anthropometry Method

Anthropometry is defined as the measurement of size, weight, body proportions

and ultimately the composition of the human body (Pérez-Escamilla and Segall-Corrêa, 2008). Anthropometric indicators measure the impact of both food insecurity and health status on the nutritional status of individuals. The anthropometric indicators most

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commonly used in national surveys are based on weight and height (or length) of infants, young children, youth and adults. The interpretation of the adequacy of the anthropometric indicators is based on well-established cut-off points.

Advantages Anthropometry Method

i. Weight and height measurements are highly standardized and are highly reproducible across individuals doing the anthropometry and across settings.

ii. It is inexpensive and this makes popular for national surveys.

iii. The cut-off points used to interpret anthropometric measures are relatively stronger on their evidence based compared to the cut-off points for establishing the adequacy of nutrient intakes.

iv. It also allows for mapping nutritional security from the local to the national level and for understanding trends, determinants and consequences of malnutrition at the individual level.

Disadvantages of Anthropometry Method

i. the indicators used are an indirect approximation to food insecurity, as they measure nutritional status which is the result of the interaction between food (in)security and health status.

ii. the interpretation of the relationship between food insecurity and obesity is complex, as there is growing evidence that whereas severe food insecurity leads to wasting, mild to moderate food insecurity may lead to obesity (Pérez-Escamilla and Segall-Corrêa, 2008).

v. Food insecurity experience-based measurement scales

All the methods discussed above are derived or indirect measurements of the food insecurity. Household food insecurity has also been measured using scales based on the perception or experience reported by the affected individuals.

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