Over the last four decades the number of underweight children and adolescents worldwide has decreased despite population growth, according to a recent study published in The Lancet this month.  However, obesity has increased. 

From 1975 to 2016, children's and adolescents' age-standardised mean BMI increased globally and in most regions.  Overall, the prevalence of ‘moderate and severe underweight’ children decreased from 9·2% in 1975 to 8·4% in 2016 in girls and from 14·8% in 1975 to 12·4% in 2016 in boys.  However, the global prevalence of obesity increased from 0·7% in 1975 to 5·6% in 2016 in girls, and from 0·9% in 1975 to 7·8% in 2016 in boys.

The study pooled 2416 population-based studies on 128·9 million participants aged 5 years and older.  It then estimated trends from 1975 to 2016 in 200 countries for mean BMI, classifying people into the following five categories: moderate and severe underweight, mild underweight, healthy weight, overweight but not obese, and obesity. 

The largest proportional decline in the prevalence of moderate and severe underweight children occurred in Polynesia and Micronesia and in southern Africa, where prevalence declined by an average of up to one third per decade for girls and by about one fifth per decade for boys from 1975 to 2016. 

In 2016, Ethiopia had the lowest age-standardised mean BMI for both sexes.  Other countries with low BMI in both sexes in 2016 were Niger, Senegal, India, Bangladesh, Myanmar, and Cambodia.  At the other extreme, age-standardised mean BMI was more than 24 kg/m2 in girls and boys in the Cook Islands and Niue and girls in Samoa, which was greater than that for adults in over 36 countries. 

Being underweight, overweight, or obese during childhood and adolescence is associated with adverse health consequences.  It is clear that we need to continue to work on food security in low-income countries and households, especially in south Asia. In a recent comprehensive study, Oxfam identified that that overconsumption, misuse of resources and waste increase hunger.  A lack of investment in agriculture and infrastructure in impoverished countries also plays a part, as does politics and corruption.  Yet the experiences of east Asia and Latin America and the Caribbean also show that the transition from underweight to overweight and obesity can be rapid, and needs to be managed in a healthy way. 

However, this is another study that makes clear that the population growth over the last four decades has not led to more hunger.

Shannon Roberts

Shannon Roberts is co-editor of MercatorNet's blog on population issues, Demography is Destiny. While she has a background as a barrister, writing has been a life-long passion and she has contributed...