Most significant updates on undernourishment estimates are the new standards for human energy requirements released in 2004 by FAO, WHO and UNU as well as the new standards of Body Mass Index released in 2006 by WHO. These new standards, used for the first time in SOFI 2008, affect the minimum dietary energy requirements (MDER) established by FAO. MDER is a crucial factor in FAO’s undernourishment methodology, as it establishes a cut-off point, or threshold, to estimate the prevalence (percentage) of the undernourished population in a country. When the threshold, or cut-off point changes, so does the prevalence of people estimated to be undernourished. Dietary energy requirements differ by gender and age, and for different levels of physical activity. Accordingly, minimum dietary energy requirements, the amount of energy needed for light activity and minimum acceptable weight for attained-height, vary by country, and from year to year depending on the gender and age structure of the population. For an entire population, the minimum energy requirement is the weighted average of the minimum energy requirements of the different gender-age groups in the population. It is expressed as kilocalories (kcal) per person per day. Particularly in countries with a high prevalence of undernourishment, a large proportion of the population typically consumes dietary energy levels close to the cut-off point, making the MDER a highly sensitive parameter. In most countries, the new human energy requirement standards have resulted in an overall drop in the amount of food required, and a decline in the prevalence of undernourishment.