The second target of the Sustainable Development Goal for Hugner (SDG-2) includes ending “all forms of malnutrition”, including acheiving, by 2025, “the internationally agreed targets on stunting and wasting in children under 5 years of age.”
Stunting refers to low height-for-age. Stunting results from a failure to grow over time and reflects chronic deficiency.
Wasting refers to low weight-for-height. A wasted child appears very thin. Wasting can take place rapidly and reflects current (or recent) deprivation.
Underweight can be a result of either stunting or wasting (or both), so these two indicators are considered more precise. Although the conditions can overlap, they have different determinants (and respond to different interventions). In children, underweight refers to low weight-for-age.
(Source: Black et al. 2013, 2008; UN Sustainable Development 2015)