Existing evidence shows that the prevalence of obesity and overweight is increasing worldwide, with significant health and economic implications( Reference Gortmaker, Swinburn and Levy 1 ). Between 1980 and 2013, combined prevalence rose by 27·5 % in adults and 47·1 % in children( Reference Ng, Fleming and Robinson 2 ). Malnutrition with rapid overweight and obesity emergence has been recognized as a major public health problem in developing countries( Reference Doku and Neupane 3 ).
With rapid industrialization, these countries are facing a growing epidemic of overweight/obesity in children and adolescents( Reference Cai 4 ). However, in sub-Saharan Africa, most nutrition efforts still concentrate on undernutrition in children( Reference Tadesse, Derso and Alene 5 ). Studies in developing countries have shown that this increased prevalence of overweight/obesity among children varies from 20·1 % in Kenya, 21·1 % in urban Vietnam, 23·6 % in Nigeria to 9 % in the Recife metropolitan region, Brazil, and 8·42 % in Punjab, India( Reference Tadesse, Derso and Alene 5 ). In South Africa, the prevalence of obesity among children aged 3–16 years was found to be 3·2 % for boys and 4·9 % for girls. In the same study, the prevalence of overweight was also higher in girls (17·9 v. 14·0 % in boys)( Reference Peltzer and Pengpid 6 ). In Togo, according to the last Demographic and Health Survey, the prevalence of overweight among children under 5 years of age was 2 %( 7 ). In a single-centre study in Togo, Djadou et al. showed obesity and overweight prevalence of 1·72 and 2·86 %, respectively. The prevalence of overweight (obesity included) was significantly higher among girls and among pupils aged 15 and 16 years old( Reference Djadou, Sadzo-Hetsu and Koffi 8 ).
The increasing prevalence of childhood overweight/obesity is a likely consequence of behavioural changes in transitional countries( Reference Cai 4 ). Urbanization can improve children’s diets but can also bring a number of unhealthy dietary changes, such as increased consumption of saturated fats, sugars and processed foods containing excessive amounts of these components( Reference Kennedy, Nantel and Shetty 9 ). Coupled with sedentary behaviour, they seem to have contributed to the dramatic rise in overweight and obesity prevalence in low-income countries( Reference Ruel and Garret 10 ).
Childhood obesity has been linked to various adverse physical, psychological and social outcomes, including type 2 diabetes, CVD, cancer, depression, low self-esteem and diminished quality of life( Reference Zhou, Dang and Zeng 11 ).
Information on the nutritional status of schoolchildren in Togo is incomplete and the factors associated with overweight/obesity development in this context need to be identified. Therefore, the aims of the present study were to estimate overweight and obesity prevalence rates in children from primary schools in the city of Lomé, Togo, and to identify potential risk factors.
Methods
Study population
A cross-sectional study was conducted during 1–16 December 2015 among children aged 8–17 years attending public and private primary schools in Lomé, Togo. A multistage, random cluster sampling method was performed to choose the class to be included. The first stage included a simple random sample to identify schools to be surveyed. Among the 363 schools in Lomé, nineteen were randomly selected in the five districts of Lomé, taking account of the number of schools by district. The second stage of sampling randomly selected one class of each selected primary school. All children in the selected class, whatever their age, were invited to participate through a letter to their parents.
Since overweight and obesity prevalence in Lomé was not well known, it was assumed to be 25 % in the study population. Hence, the minimum number of students necessary for the investigation was 288 students (number of students=(t 2×p×q)/i 2 where t=1·96, p=children supposed to have the outcome overweight/obesity, q=1−p and i=0·05). This number was doubled and then increased by 10 % to reduce fluctuations related to sampling. In view of the sampling method considered, 576 was the minimum number of students necessary for investigation.
Data collection
A standardized questionnaire was used to collect data by trained medical students( Reference Kennedy, Ballard and Dop 12 , Reference Truby and Paxton 13 ) and was administered face-to-face to each participating child. Dietary intake was estimated by the 24h recall questionnaire. Children were asked to report consumed food in the last 24h for breakfast, morning snack, lunch, afternoon snack and dinner, as well as any other snacking that had occurred during the day. Data on snacking and water and soft drink consumption were also recorded. The questions on dietary diversity, developed and validated by the FAO, were used as the basis for the questionnaire. Each of the twelve food groups defined by the FAO was scored either as 1 or 0, as an indication of respectively consumption or non-consumption of these foods in the past 24h. We therefore constructed a score by summing each food group recorded (minimum score=0, maximum score=12). Other variables that were collected included age, gender, family conditions (including parental income and living space), food habits, anthropometric measurements, physical activity (sport in and outside school, means of commuting to and from school) and sedentary behaviour (including time spent watching television or playing video games).
Anthropometric measurements
Weight and height were recorded by specially trained medical students. Standardized methods and techniques were used to measure weight and height as described by the WHO( 14 ). Weight was measured to the nearest 100g with an electronic scale with children wearing only light clothing and without shoes. Height was measured with a wooden stadiometer to the nearest 0·1cm, placed on a flat surface, the children stood on the basal part of the device with feet together (without shoes) and standing with their eyes in the horizontal plane. BMI was calculated as weight in kilograms divided by the square of height in metres. Overweight and obesity thresholds were categorized as proposed by the International Obesity Task Force( Reference Cole, Bellizi and Flegal 15 ). Therefore, thinness was classified as the equivalent to BMI <18·5 kg/m2 in adults and overweight and obesity were classified as corresponding to BMI≥23 kg/m2 and BMI≥27 kg/m2 in adults, respectively.
Socio-economic conditions
Data were collected on household type and size, number of rooms and bedding conditions, as well as on the availability of comfort items such as air conditioning, electricity and tap water. They served to compute socio-economic status (SES) scores( Reference Ruel 16 ). SES was considered as low (score=0–3) in households with no access to tap water or electricity and with residents sleeping on the floor. However, high SES (score=4–6) was attributed to children living in brick houses, having access to tap water and electricity, and sleeping on beds.
Dietary diversity assessment
Food diversity was defined by the recognition of twelve food groups (candies, cereals, condiments, dairy products, eggs, fats, fish, fruits, legumes, meats, tubers and vegetables) consumed in the last 24 h( Reference Hatloy, Hallund and Diarra 17 ). Food items that did not belong to one of the mentioned groups were excluded. Three levels of dietary diversity were defined: low (≤3 food groups), medium (4–5 food groups) and high (≥6 food groups)( Reference Hatloy, Hallund and Diarra 17 ).
Statistical analysis
Continuous variables were expressed as mean values and compared by Student’s t test. Categorical variables were presented as proportions and compared by Fisher’s exact test. Bivariate analysis identified factors associated with overweight/obesity. All potential risk factors, with P≤0·30 in bivariate analysis, were entered in a step-wise logistic multivariate regression model. The study objectives were to ascertain overweight and obesity prevalence rates among Togolese schoolchildren and their correlation with physical activity, socio-economic conditions and eating habits. Therefore, we decided to force variables concerning dietary habits into the multivariate model, even if P values were higher than 0·30. Model data fit was assessed by the Hosmer–Lemeshow goodness-of-fit test. In all tests performed, two-tailed P<0·05 values were regarded as denoting statistical significance. Statistical data were analysed with the statistical software package IBM SPSS Statistics for Windows, version 24.0.
Ethical considerations
The Ministry of Primary Schools granted permission and provided a list of primary schools in the municipality of Lomé. The directors of the schools selected were contacted and approved their participation. Clear printed information was sent to the parents of all participating children. The objectives and type of data to be collected were explained. We reassured parents that there was no safety issue to be raised about the participation of their children; on the contrary, their cooperation would be helpful to improve children’s health care. The National Ethics Committee and the Ministry of Health in Togo approved the study.
Results
A total of 634 students from public (41·8 %) and private (58·2 %) primary schools in Lomé were included in the study. Median age was 11 years, and 81·8 % of the students were under 13 years old. Girls outnumbered boys (54·6 % and 45·4 %, respectively), with most of the included children (80 %) having at least six siblings. Household income was mostly low (94·7 %), despite high percentages of working parents (98·7 % of fathers and 92·6 % of mothers).
Mean weight of the participating children was 33·7 kg (range 18–84 kg). BMI ranged from 10·2 to 36·7 kg/m2 with a mean of 16·25 kg/m2. Values of anthropometric parameters were much higher in girls than in boys (Table 1).
Table 1 Height, weight and BMI of boys and girls included in the random sample of children from primary schools in Lomé, Togo, December 2015
Min–max, minimum–maximum.
The overall prevalence of thinness, overweight and obesity among the included children was 18·5, 5·2 and 1·9 %, respectively. Overweight prevalence in girls was two times higher than in boys (6·4 and 3·8 %, respectively, P=0·21). Thinness prevalence was, however, similar in both genders. Table 2 reports the anthropometric data by gender.
Table 2 Normal weight, thinness, overweight and obesity prevalence, according to International Obesity Task Force cut-offs, in boys and girls included in the random sample of children from primary schools in Lomé, Togo, December 2015
Results showed that 68·4 % of children ate three principal meals, usually at home. Dairy products, fruits and vegetables were consumed daily by 5·3, 25·8 and 84·1 %, respectively. The daily ingestion of other foods was 99·7 % for cereals, 51·1 % for fish, 38·1 % for meats, 25·5 % for vegetables, 14·5 % for eggs and 7·9 % for tubers. We noticed that 35·3 and 13·1 % of students, respectively, consumed sweets and fats daily.
A total of 77·7 % of children participated in physical activity; 51·6 % during weekends and 48·4 % at school. In addition, 88·2 % of included children went to school by foot. For 78·8 % of them, it took at least 30 min to reach school. Tables 3 and 4 enumerate the data on physical activities, dietary habits and dietary diversity.
Table 3 Description of sociodemographic and lifestyle characteristics in the random sample of children from primary schools in Lomé, Togo, December 2015
Min–max, minimum–maximum.
* Professional category: Group 1=executive, professor; Group 2=self-employed, farmer, artisan, storekeeper, employee, worker; Group 3=unemployed.
Table 4 Eating habits, place of meals and dietary diversity score in the random sample of children from primary schools in Lomé, Togo, December 2015
Bivariate analysis indicated that watching television for more than 4 h on weekends, going to school by car and consuming dairy products were significantly associated with overweight/obesity (Table 5). Candy consumption was identified as a risk factor of overweight/obesity, but the association was not significant. Having six to ten siblings or eating breakfast in the school cafeteria was linked to a lower risk of high BMI.
Table 5 Bivariate analysis of factors associated with overweight and obesity in the random sample of children from primary schools in Lomé, Togo, December 2015
NC, not calculable.
Multivariate logistic regression analysis (Table 6) showed that watching television for more than 4h on weekends and having a medium dietary diversity score were independently associated with overweight and obesity. Children consuming fruits and breakfast in the school cafeteria were significantly less likely to be overweight or obese.
Table 6 Multivariate logistic regression of factors independently associated with overweight and obesity in the random sample of children from primary schools in Lomé, Togo, December 2015
NC, not calculable.
Discussion
Obesity and overweight are major public health problems among children, with significant health, demographic and socio-economic implications( Reference Ng, Fleming and Robinson 2 ). Food environments have changed in past decades and obesity and overweight rates have increased dramatically in both developing and developed countries( Reference Ng, Fleming and Robinson 2 ). The present study assessed nutritional status in a random sample representative of schoolchildren attending primary schools in urban areas of Lomé, the capital city of Togo. It also investigated the factors associated with overweight/obesity. The study established that overweight and obesity prevalence is less than 8 % and linked with sedentary behaviour, poor eating habits and limited dietary diversity.
Overweight and obesity prevalence was lower than what has been reported in the literature( Reference Ene-Obong, Ibeanu and Onuoha 18 , Reference Abril, Manuel-y-keenoy and Solà 19 ). Although this prevalence was similar to that in other studies( Reference Jinabhai, Taylor and Sullivan 20 , Reference Prista, Maia and Damasceno 21 ), it was higher than the rate among pre-school Togolese children participating in a cross-sectional study conducted in twenty-six African countries( Reference Gebremedhin 22 ). Several others have shown that urban children, because of favourable environmental and socio-economic conditions, generally manifest better nutritional status than their rural counterparts( Reference Ene-Obong, Ibeanu and Onuoha 18 ). A similar study among rural children will be necessary to confirm or refute this hypothesis in Togo.
The present survey found higher prevalence rates of overweight and obesity in girls than in boys, which concurs with other reports from low- and middle-income countries, but the opposite held true in high-income countries where overweight and obesity rates were higher in boys than in girls( Reference Peltzer and Pengpid 6 , Reference Armstrong, Lambert and Sharwood 23 , Reference Kimani-Murage, Kahn and Pettifor 24 ). This observation might be related to cultural behaviours( Reference Puoane, Tsolekile and Steyn 25 , Reference Kruger, Puoane and Senekal 26 ). Differences in physical activity and energy expenditure between boys and girls may also have contributed to the lower prevalence of overweight and obesity among boys.
Differences in published data on prevalence may be explained by study design, population included and cut-offs defining overweight and obesity( Reference Flegal, Ogden and Wei 27 ). Indeed, many cut-off values have been published; each method has its advantages and limitations, and should be used cautiously( Reference Flegal, Ogden and Wei 27 ).
While overweight and obesity in children have definitely become a worldwide public health concern, malnutrition remains the greatest problem in developing countries( Reference Caleyachetty, Rudnicka and Echouffo-Tcheugui 28 , Reference Li, Yang and Xiong 29 ). In the present study, thinness prevalence was 18·5 % and was similar in both genders. Given the fact that severe underweight is almost always a sign of malnutrition we can assume that malnutrition persists in Togo, even in urban areas. In addition, some overweight/obese children may be malnourished as well.
Obesity prevention campaigns are considered to be successful through changes in environments such as schools, especially if they occur early in life( Reference Abril, Manuel-y-keenoy and Solà 19 ). Thus, it is particularly relevant to identify the factors associated with overweight and obesity in primary-school populations in the specific context of urban settings in a country in transition, such as Togo.
Findings on dietary diversity in the present study indicated that many schoolchildren had diets with little variety, as disclosed by the fact that one-third of them consumed fewer than four food groups daily( Reference Herrador, Perez-Formigo and Sordo 30 ). The most neglected food groups were dairy products, tubers, eggs, fruits, meats and vegetables, as reported in other investigations( Reference Steyn, Villiers and Gwebushe 31 , Reference Steyn, Nel and Labadarios 32 ). Numerous studies have shown that skipping breakfast or reducing the number of meals consumed per day is a significant independent predictor of overweight in schoolchildren( Reference Utter, Scragg and Mhurchu 33 , Reference Yang, Wang and Hsieh 34 ). Significant relationships with these eating habits were not observed here, as reported in other works( Reference Abril, Manuel-y-keenoy and Solà 19 ), but it should be noted that more than two-thirds of children in the present sample ate breakfast.
Increased obesity has been attributed to a growing trend of snacking( Reference Sahoo, Sahoo and Choudhury 35 ). In the current study, snacking in the morning was associated with a high risk of overweight/obesity but the relationship was not significant. Snacking may contribute to excess energy intake and weight gain( Reference Bellisle 36 ). Harmonizing definitions of snacks is crucial, as is adopting a validated research strategy to evaluate their real impact on weight gain( Reference Bellisle 36 ).
SES affects access to culturally appropriate and affordable foods, affecting dietary quality( Reference Gebremedhin 22 ). In developing countries, it is assumed that overweight is relatively common in urban settings and in socio-economically privileged households( Reference Gebremedhin 22 ). In the present study, the risk of overweight/obesity was higher with upper SES compared with low or medium SES. This is not surprising because of the higher purchasing power for gadgets such as televisions and video games that goes with upper SES. Therefore, decreased physical activities are expected in these children because of sedentary behaviour, altered eating patterns and increased consumption of unhealthy foods( Reference Adesina, Peterside and Anochie 37 ). However, the absence of a significant association may be partly explained by possible rapid nutrition transition and the methodological weaknesses of wealth indices as measures of household economic status( Reference Gebremedhin 22 ).
Multivariate analysis showed that sedentary lifestyles related to watching television and poor dietary habits, including low dietary diversity scores and place of breakfast consumption, were significantly coupled with overweight and obesity in the present sample of Togolese schoolchildren, whereas the risk was 64 % less in children who consumed fruits.
Television viewing for over 4 h on weekends was associated with increased overweight and obesity prevalence. This risk might be explained by several mechanisms, including reduction of time spent on intense activities, lower metabolic rate and frequent snacking( Reference Adesina, Peterside and Anochie 37 , Reference Prentice-Dunn and Prentice-Dunn 38 ).
The present results showed that practising sport was not associated with decreased risk of overweight/obesity, given the unpredictable temporality of the relationship between physical activity and overweight with a cross-sectional study design. Moreover, activities such as outdoor games, family events and daily travel means (walking and biking) should also be considered to evaluate the impact of physical activity. This is highlighted by the significant impact of walking in reducing the risk of overweight/obesity in our bivariate analysis.
Dietary patterns have changed in many countries in past decades. Increased intakes of soft drinks and candy and decreased consumption of fruits and vegetables have been associated with amplified childhood obesity( Reference Vartanian, Schwartz and Brownell 39 ). This observation is in agreement with other studies that showed a negative association between fruit consumption and overweight( Reference Pawloski, Kitsantas and Ruchiwit 40 , Reference Roseman, Yeung and Nickelson 41 ).
Dietary diversity represents the extent to which foods of the different food groups are consumed in the last 24 h. The current cross-sectional results, which indicated an association between dietary diversity score and BMI, were consistent with those of several other cross-sectional studies, but were also inconsistent with some presenting no significant positive associations( Reference Ey Chua, Zalilah and Ys Chin 42 , Reference Fernandez, Kasper and Miller 43 ).
The lack of consistency in the literature concerning dietary diversity may be partly attributed to different cut-off points used to determine if the consumption of particular foods counts in diversity scores( Reference Cafiero, Melgar-Quiñonez and Ballard 44 ). Despite the importance of dietary quality in the assessment of nutritional profile, increasing the variety of healthy foods in children’s diets requires careful consideration for obesity control and prevention( Reference Steyn, Nel and Labadarios 32 ). In some studies (as in the current one), simple counting of foods consumed within food groups is a measure of diversity( Reference Fernandez, Kasper and Miller 43 ). However, the lack of precision in determining portion sizes makes accurate assessment very difficult.
To our knowledge, the present study is the first multicentre one to assess the prevalence of overweight/obesity in Togolese schoolchildren. It is noteworthy that the identification of factors determining overweight/obesity in schoolchildren has several limitations. Conclusions for true individual change cannot be derived from this cross-sectional design which precludes inferences of causal associations. In addition, the study was restricted to schoolchildren in the urban setting of Lomé and the findings may not be extrapolated to rural populations, despite the fact that attending school is mandatory in Togo. However, we have used a random multistage cluster sampling to identify the study population that probably represents the general schoolchild population of Lomé. Another limitation was that other factors such as maternal pre-pregnancy weight, birth weight, sleep quality and parental anthropometric measurements, education level, income and lifestyle (to assess genetic and family influences), which may strongly impact the presence of overweight/obesity in schoolchildren( Reference Li, Yang and Xiong 29 ), were not recorded. Yet another study limitation was the methodology implemented, namely a single 24 h recall, which relied on children to remember what they had eaten the day before( Reference Cafiero, Melgar-Quiñonez and Ballard 44 ). The results may have been biased in terms of food items that were left out. Furthermore, this method did not distinguish children who ate small or large portions of food items since food sizes eaten were not recorded. In addition, a recall bias and a measurement error should be mentioned due to the use of self-reported rather than objectively measured physical activity and sedentary behaviour.
Despite these limitations, the current study analysed a large sample to estimate overweight and obesity patterns in urban primary-school children in Lomé, Togo. Body weight of children should be assessed in schools and communities as part of an overall public health strategy. Early detection of weight problems would allow decision makers to implement interventions to reduce associated morbidity and mortality. Health education should be inculcated into school programmes to banish unhealthy behaviours, such as lack of physical activity, food overconsumption and long-term sedentary lifestyles, among school-aged children. Also, children from some areas have very little influence on their food choices, so it appears necessary to educate parents about dietary quality and healthy eating( Reference Savage, Fisher and Birch 45 ).
Acknowledgements
Acknowledgements: Medical editing services were provided by Mr Ovid M. Da Silva, a native English speaker. The authors thank the directors of schools participating in this study and the Ministry of Primary Schools for approving and contributing to performance of the survey. Financial support: This research received no specific grant from any funding agency, commercial or not-for-profit sectors. Conflict of interest: N.K. received a PhD grant from Sanofi Pasteur, personal fees from Astellas and non-financial support (travel expenses) from Alere and Sanofi Pasteur. P.V. received scientific grants from Sanofi Pasteur, Sanofi MSD and Anios, and personal fees from Sanofi Pasteur, BioMérieux, GlaxoSmithKline and Sanofi MSD. The financial and non-financial support for N.K and P.V. were not related to this work. The other authors have no conflicts of interest to declare. Authorship: H.S. contributed to data analysis and interpretation as well as manuscript drafting. D.K.E., S.N. and Y.K. conceived the study and were involved in data acquistion, manuscript revision and final approval. D.T.R. collected and entered data on all participating schools. S.D. constructed the digital database. F.B., A.A. and P.V. partook in data interpretation and final manuscript approval. N.K. contributed to data analysis and interpretation, and wrote the manuscript. All authors have approved the final manuscript version. Ethics of human subject participation: The National Ethics Comittee and the Ministry of Health in Togo approved the study. The Ministry of Primary Schools granted permission to conduct the study in primary schools in the municipality of Lomé; and the selected school directors and parents of all participating children consent provided their consent.
