This study aimed to identify individual and contextual factors that are associated with under- and over-nutrition among school-aged children and adolescents in two Nigerian states.

Community-based cross-sectional study.

The study was carried out in rural and urban communities of Osun and Gombe States in Nigeria.

A total of 1200 school-aged children and adolescents.

Multi-level analysis showed that the full models accounted for about 82 % and 39 % of the odds of thinness or overweight/obese across the communities, respectively. Household size (adjusted OR (aOR) 1·10; P = 0·001; 95 % CI (1·04, 1·16)) increased the odds, while the upper wealth index (aOR 0·43; P = 0·016; 95 % CI (0·22, 0·86)) decreased the odds of thinness. Age (aOR 0·86; P < 0·001; 95 % CI (1·26, 8·70)), exclusive breastfeeding (aOR 0·46; P = 0·010; 95 % CI (0·25, 0·83)), physical activity (aOR 0·55; P = 0·001; 95 % CI (0·39, 0·78)) and the upper wealth index (aOR 0·47; P = 0·018; 95 % CI (0·25, 0·88)) were inversely related with overweight/obesity, while residing in Osun State (aOR 3·32; P = 0·015; 95 % CI (1·26, 1·70)), female gender (aOR 1·73; P = 0·015; 95 % CI (1·11, 2·69)) and screen time > 2 h/d (aOR 2·33; P = 0·005; 95 % CI (1·29, 4·19)) were positively associated with overweight/obesity.

The study shows that selected community and individual-level factors are strongly associated with thinness and overweight/obesity among school-aged children and adolescents.

We examined the trends over time and the factors associated with malnutrition among adolescent girls in Ghana.

Cross-sectional analysis from 3 nationwide Ghana Demographic and Health Surveys conducted in 2003 (n 983), 2008 (n 955) and 2014 (n 857). We used Cox proportional hazard models with sample weighting to model the prevalence ratio (PR) of malnutrition.

Countrywide, covering rural and urban areas in Ghana.

Non-pregnant adolescent girls aged 15–19 years.

Compared with 2003, thinness declined marginally (PR 0·88 (95 % CI 0·45, 1·73)) in 2008 and in 2014 (PR 0·71 (95 % CI 0·38, 1·56)). Stunting declined marginally by 19 % in 2008 (PR 0·81 (95 % CI 0·59, 1·12)), flattening out in 2014 (PR 0·81 (95 % CI 0·57, 1·17)). We found an increasing trend of overweight/obesity with the PR peaking in 2014 (PR 1·39 (95 % CI 1·02, 1·88)) compared to 2003. The anaemia prevalence remained severe without a clear trend. A low level of education of the adolescent girl was positively associated with stunting. Increasing age was positively associated with stunting but inversely associated with thinness and anaemia. Girls who ever bore a child were more likely to be anaemic compared to those who never did. A lower level of household wealth and a unit increase in household size was negatively associated with overweight/obesity. Urban dwelling girls were less likely to be stunted.

The stagnant burden of under-nutrition and rising over-nutrition emphasise the need for double-duty actions to tackle malnutrition in all its forms in Ghanaian adolescent girls.

To examine secular trends and sociodemographic determinants of thinness, overweight and obesity among Malaysian children and adolescents from 2006 to 2015.

We used cross-sectional data from the National Health and Morbidity Surveys 2006, 2011 and 2015. Individuals were classified into pre- (6–9 years), early (10–13 years) and mid- (14–17 years) adolescence. BMI status was determined according to the International Obesity Task Force (IOTF) and WHO criteria, using measured height and weight. We analysed trends using log-binomial regression, by sex-age groups, stratified by sociodemographic factors (ethnicity, residential area, household size and household income), and accounting for the complex survey design. Associations between sociodemographic factors and prevalence of thinness and overweight (obesity included) in 2015 were assessed using log-Poisson regression.

Nationwide population-based surveys, Malaysia.

Eligible 6–17-year-olds from urban and rural residential areas (n 28 094).

The prevalence of thinness decreased from 2006 to 2015 (IOTF: boys from 22 % to 18 %, girls from 23 % to 19 %; WHO: boys from 9 % to 7 %, girls from 8 % to 6 %), while the prevalence of overweight increased (IOTF: boys from 20 % to 26 %, girls from 19 % to 24 %; WHO: boys from 25 % to 31 %, girls from 22 % to 27 %). These changes were statistically significant in most sex-age groups. Thinness and overweight co-existed in all sociodemographic subgroups, with variation in the prevalence estimates, but similar secular changes in most subgroups.

Malaysia is facing a double burden of malnutrition at population level with a secular increase in overweight and obesity and a gradual decrease in thinness among 6–17-year-olds from varying sociodemographic backgrounds.

BMI is a time-intensive measurement to assess nutritional status. Mid-upper arm circumference (MUAC) has been studied as a proxy for BMI in adults, but there is no consensus on its optimal use.

We calculated sensitivity, specificity and area under receiver operating characteristic curve (AUROCC) of MUAC for BMI < 18·5, <17 and <16 kg/m2. We designed a system using two MUAC cut-offs, with a healthy (non-thin) ‘green’ group, a ‘yellow’ group requiring BMI measurement and a ‘red’ group who could proceed directly to treatment for thinness.

We retrospectively analysed monitoring data collected by the International Committee of the Red Cross in places of detention.

11 917 male detainees in eight African countries.

MUAC had excellent discriminatory ability with AUROCC: 0·87, 0·90 and 0·92 for BMI < 18·5, BMI < 17 and BMI < 16 kg/m2, respectively. An upper cut-off of MUAC 25·5 cm to exclude healthy detainees would result in 64 % fewer detainees requiring BMI screening and had sensitivity 77 % (95 % CI 69·4, 84·7) and specificity 79·6 % (95 % CI 72·6, 86·5) for BMI < 18·5 kg/m2. A lower cut-off of MUAC < 21·0 cm had sensitivity 25·4 % (95 % CI 11·7, 39·1) and specificity 99·0 % (95 % CI 97·9, 100·0) for BMI < 16 kg/m2. An additional 50 kg weight requirement improved specificity to 99·6 % (95 % CI 99·0, 100·0) with similar sensitivity.

A MUAC cut-off of 25·5 cm, above which detainees are classified as healthy and below receive further screening, would result in significant time savings. A cut-off of <21·0 cm and weight <50 kg can identify some detainees with BMI < 16 kg/m2 who require immediate treatment.

To estimate the prevalence of thinness, overweight and obesity among Tibetan adolescents aged 12–17 years.

Cross-sectional survey.

Shigatse City of Tibet municipality, with an average altitude of more than 4000 m.

Study participants included 2642 adolescents aged 12–17 years selected from six schools using a convenient cluster sampling method.

The prevalence of thinness/overweight/obesity among Tibetan adolescents was 9·4 %/5·4 %/1·4 % (China definition), 14·7 %/4·4 %/0·7 % (International Obesity Task Force (IOTF) definition), and 2·8 %/5·7 %/0·9 % (WHO definition). The prevalence of thinness and overweight was significantly different between both sexes based on each of three BMI classification criteria (P < 0·001). There was no significant difference in the prevalence of obesity between both sexes according to each of three BMI criteria. There was no clear trend in the prevalence of thinness across ages according to the China or IOTF definition (both P > 0·05), whereas an upward trend was observed for thinness in boys according to the IOTF definition (P for trend <0·05). In contrast, the prevalence of thinness tended to decrease with increasing age in girls according to the IOTF definition and in total sample according to the WHO definition (P for trend <0·05).

Among Tibetan adolescents, the prevalence of overweight and obesity is relatively low, while the prevalence of thinness is high, especially in boys. These data suggest urgent attention is needed to control adolescent thinness in Tibet.

To evaluate the performance of mid-upper arm circumference (MUAC) to identify thinness in the late adolescence period (aged 15–19 years) in Ethiopia.

We conducted a school-based cross-sectional study. The receiver operating characteristics curve was used to examine the validity of MUAC compared with BMI Z-score to identify adolescents with thinness (BMI Z-score <−2 sd).

Fifteen high schools (grade 9–12) located in Addis Ababa, Ethiopia.

A total of 851 adolescent (456 males and 395 females) were included in the study.

The prevalence of thinness and severe thinness among high-school adolescents in Addis Ababa was 9·5 % (95 % CI 7·7, 11·7 %). The overall AUC for MUAC against BMI Z-score <−2 SD was 0·91 (95 % CI 0·88, 0·93). The optimal MUAC cut-offs to identify thinness were 23·3 cm for males and 22·6 cm for females. These cut-off points give high sensitivity and specificity for both males (a sensitivity of 87·9 % and a specificity of 75·9 %) and females (a sensitivity of 100 % and a specificity 88·2 %).

MUAC has a comparable level of accuracy with BMI Z-score to identify thinness in adolescents aged 15–19 years. Hence, MUAC could be used as an alternative tool for surveillance and screening of thinness among adolescents aged 15–19 years. The optimum cut-off proposed by this study may incorrectly include a large number of adolescents when used in a relatively well-nourished population. In this situation, it would be necessary to choose a cut-off with greater positive predictive value.

Thinness is rarely highlighted or regularly monitored among children in developed countries although it may be rather frequent and pose a significant risk to children’s health. We aimed to describe the prevalence of mild, moderate and severe thinness among young Serbian schoolchildren.

Cross-sectional study of schoolchildren aged 6–9 years. Children were assessed for weight, height and BMI as part of the WHO European Childhood Obesity Surveillance Initiative in Serbia. Thinness grades were defined as gender- and age-specific cut-offs for BMI according to the International Obesity Task Force criteria.

Serbia, September to November 2015.

Students (n 4861) in grades 2 and 3 (6–9 years, 2397 girls).

Overall prevalence of thinness in Serbian schoolchildren was 9·6 %. Mild thinness was clearly the largest category with a prevalence of 7·6 %, moderate thinness was present in 1·7 % of children and severe thinness was found in 0·3 % of children. OR indicated a significant risk of being thin for girls (1·44 times higher compared with boys) and children attending schools with no health-focused educational programme (1·57 times more likely to be thin than peers enrolled in schools with such programmes). In addition, OR for thinness tended to be 1·23 times higher in children living in an economically disadvantaged region of Serbia (P=0·06).

A rather high prevalence of thinness highlights this malnutrition disorder as an emerging health issue that should trigger public health policies to tackle thinness, especially in girls of young age and children living in economically disadvantaged areas.

Nutritional status during childhood plays an important role in the human life cycle. The present study examined the prevalence trends in different grades of nutritional status (thinness, normal weight, overweight and obesity) among children and adolescents in Shandong, China.

Data for the study were obtained from six cross-sectional surveys of schoolchildren carried out in 1985, 1995, 2000, 2005, 2010 and 2014. Height and weight of all children were measured; BMI was calculated from their height and weight. International BMI cut-offs were used to define thinness, overweight and obesity.

Shandong Province, China.

A total of 56 045 students aged 7–18 years were included in the current analysis.

In the past 29 years, the prevalence of thinness decreased from 18·22 % and 23·45 % in 1985 to 7·18 % and 9·49 % in 2014 for boys and girls, respectively. Conversely, the prevalence of combined overweight and obesity increased from 1·79 % and 1·66 % in 1985 to 31·12 % and 20·11 % in 2014 for boys and girls, respectively.

The nutritional profile of Shandong children and adolescents had an obvious change over the past 29 years. Special attention should be paid to controlling the rapid rise of childhood overweight and obesity.

We aimed to investigate the prevalence of grade 1, 2 and 3 thinness among Chinese children and to explore their associations with socio-economic status (SES).

A population, school-based cross-sectional study using multistage, stratified cluster random sampling. Grade 1, 2 and 3 thinness, overweight, obesity and severe obesity were defined by the International Obesity Task Force BMI cut-offs.

Seven districts of Shanghai, China.

Chinese children aged 3–12 years (n 84 075).

In boys and girls, respectively, the prevalence of grade 1 thinness was 8·89 % and 11·78 %, of grade 2 thinness was 2·80 % and 3·74 %, and of grade 3 thinness was 2·23 % and 2·93 %. Compared with urban children, suburban children had higher prevalence of thinness. Children whose parent had low education had higher prevalence of grade 1, 2 and 3 thinness than those whose parent had high education. The prevalence of grade 2 and 3 thinness, obesity and severe obesity in low-SES children was higher than that in high-SES children, and the prevalence of grade 1 thinness was lower than that in high-SES children. Particular patterns of prevalence of grade 1, 2 and 3 thinness appeared in low-, middle- and high-SES children.

The study describes associations of SES with grade 1, 2 and 3 thinness, overweight, obesity and severe obesity in Shanghai children. The patterns of thinness and obesity in Shanghai provide further insights into BMI patterns in mega-cities in developing countries.

According to most prospective studies, being underweight (BMI<18·5 kg/m2) is associated with significantly higher mortality than being of normal weight, especially among smokers. We aimed to explore in a generally lean population whether being underweight is significantly associated with increased all-cause mortality.

Prospective cohort study.

Korea Medical Insurance Corporation study with 14 years of follow-up.

After excluding deaths within the first 5 years of follow-up (1993–1997) to minimize reverse causation and excluding participants without information about smoking and health status, 94 133 men and 48 496 women aged 35–59 years in 1990 were included.

We documented 5411 (5·7 %) deaths in men and 762 (1·6 %) in women. Among never smokers, hazard ratios (HR) for underweight individuals were not significantly higher than those for normal-weight individuals (BMI=18·5–22·9 kg/m2): HR=0·87 (95 % CI 0·41, 1·84, P=0·72) for underweight men and HR=1·12 (95 % CI 0·76, 1·65, P=0·58) for underweight women. Among ex-smokers, HR=0·86 (95 % CI 0·38, 1·93, P=0·72) for underweight men and HR=3·77 (95 % CI 0·42, 32·29, P=0·24) for underweight women. Among current smokers, HR=1·60 (95 % CI 1·28, 2·01, P<0·001) for underweight men and HR=2·07 (95 % CI 0·43, 9·94, P=0·36) for underweight women.

The present study does not support that being underweight per se is associated with increased all-cause mortality in Korean men and women.

In developed countries, there is abundant information on the epidemic of childhood obesity, but only a few studies on trends in the dual burden of body weight (overweight and thinness).

To examine trends in overweight and thinness among 9–10-year-old Spanish children in the last decade.

Data were taken from cross-sectional studies on schoolchildren in Cuenca (Spain), conducted in 1992, 1996, 1998 and 2004 with similar methods. Weight and height were measured by trained personnel with standardized procedures. Overweight (including obesity) and thinness were defined according with the International Obesity Taskforce BMI cut-offs.

The overall prevalence of overweight increased from 24·4 % in 1992 to 30·9 % in 2004 (P = 0·07), rising from 21·2 % in 1992 to 32·0 % in 2004 (P = 0·03) among boys and from 27·7 % to 29·8 % (P = 0·67) among girls. The overall prevalence of thinness was 2·7 % in 1992 and 9·2 % in 2004 (P < 0·001); in the same period, thinness prevalence rose from 1·9 % to 9·0 % (P = 0·10) among boys and from 3·7 % to 9·5 % (P < 0·01) among girls.

The dual burden of body weight has increased among children in Cuenca in the last decade. Population-based policies addressing childhood obesity, which is the most frequent problem, should not increase the risk of thinness.

To assess the nutritional status and risk factors of undernutrition in post-menarcheal girls in rural northern Bangladesh.

Cross-sectional data on anthropometric measurements, dietary intake, work activity, morbidity and socio-economic status were collected from 12- to 19-year-old primigravidae (n 209) and never-pregnant adolescents (n 456) matched on age and time since menarche. Multiple regression analyses were conducted to determine predictors of stunting, thinness, upper-arm muscle (UAMZ) and fat area Z-scores (UAFZ) among the adolescent girls.

A large proportion of adolescents (49 %) were stunted (height-for-age Z-score <−2) and underweight (40 %; weight-for-age Z-score <−2), but not thin (BMI-for-age <5th percentile; ∼10 %). The mean (sd) UAMZ and UAFZ of the adolescent girls was −0·3 (0·64) and −0·9 (0·40), respectively. Lean mass increased whereas fat mass declined with age. Both stunting and thinness were positively associated with age and time since menarche (P < 0·05). Young age (12–14 years) and literacy were protective against stunting among pregnant adolescents (OR = 0·29, 95 % CI 0·09, 0·88 and OR = 0·50, 95 % CI 0·26, 0·96, respectively). Having symptoms of diarrhoea or dysentery (OR = 7·40, 95 % CI 1·43, 38·29) predicted thinness and was associated with lower UAMZ and UAFZ among never-pregnant girls (both P < 0·05). Performing light-to-moderate activities was protective against thinness among never-pregnant girls (OR = 0·43, 95 % CI 0·22, 0·82), whereas pregnant adolescents who performed high levels of strenuous activities had greater UAMZ (P < 0·05).

Undernutrition was widespread among this post-menarcheal adolescent population. Younger and literate adolescents were less likely to be stunted, whereas thinness and body composition were associated with morbidity and work activity.