obesity is an independent risk factor for chronic diseases , such as diabetes , cardiovascular disease ( cvd ) , and some cancers [ 1 , 2 ] , which are the leading causes of deaths worldwide . according to the world health organization , 44% of diabetes , 23% of ischemic heart disease , and 7% to 41% of some cancers are attributable to overweight and obesity .
the rising incidence of chronic diseases associated with obesity does not spare developing countries ( dcs ) even low - income ones .
who estimates that if appropriate preventive measures are not taken , 20 million deaths by 2015 will be due to cvd and 80% of this mortality burden will occur in dcs .
changes in lifestyle and diet that characterize the ongoing nutrition transition contribute to the outbreak of obesity in dcs . abdominal obesity ( ao ) is a more potent risk factor than gynoid or general obesity .
several studies have shown that africans and peoples of african descent have less visceral fat than whites , regardless of gender , age , total body fat , and bmi [ 912 ] .
the prevalence of metabolic syndrome ( mets ) is reportedly lower among african americans than in caucasians   while the prevalence of cvd and insulin resistance is higher [ 14 , 15 ] . in a nested study of african descent haitians living in montreal and white subjects paired for age , sex , and bmi , haitians had significantly less visceral fat than whites for the same waist circumference ( wc ) . in the large interheart study in 52 countries ,
the association of myocardial infarction risk with abdominal obesity was higher in europeans than in blacks   due to less visceral fat in the latter than the former .
the relationship between obesity and other cardiometabolic risk ( cmr ) factors in africans is poorly documented .
the prohibitive cost of treatment of obesity - related diseases , both for the patient and the health system , mainly in developing countries , requires that increased attention be paid to cmr assessment .
the challenge of addressing cmr factors is especially complex in sub - saharan settings where epidemiologic data related to risk factors are not readily or reliably available at present .
the purpose of our study was to assess changes in cmr factors in sub - saharan africans according to baseline obesity status and taking account of diet and lifestyle .
we hypothesized that obesity as currently defined by standard anthropometric criteria is weakly associated with unfavourable changes of other cmr factors .
this prospective observational study was conducted among benin ( west africa ) adults who were initially in apparent good health .
subjects ( n  = 541 ) aged 2560 years were randomly selected by multistage sampling and were enrolled in baseline study on cmr factors and nutrition transition .
subjects were selected in cotonou , the largest urban city ( n  = 200 ) , ouidah , a small - size city located 45  km away from cotonou ( n  = 171 ) , and the rural area surrounding ouidah ( n  = 170 ) using location data ( urban ) or after enumeration of compounds ( semiurban and rural ) .
eligible participants were beninese - born subjects having lived in the study area for at least six months .
subjects with a prior diagnosis of hypertension , diabetes or cardiac condition were excluded , but those diagnosed for high blood pressure or diabetes during the baseline study or at followup remained in the cohort , whether or not they received medical treatment .
details of sample size determination and sampling process were published elsewhere [ 18 , 19 ] .
after the baseline study ( t0 ) , subjects were followed up after 24 months ( t1 ) and 48 months ( t2 ) .
a final sample size of 350 was deemed sufficient to achieve 80% statistical power with a significance level ( alpha ) of 0.05 using logistic regression on blood pressure as main dependent variable .
data were collected between june 2005 and october 2010 by the same investigator team as the baseline study .
a laboratory technician handled the blood samples . before each biochemical data collection , participants were informed on the practical arrangements that were prior to blood sampling : ( 1 ) an overnight fast of at least 12 hours , ( 2 ) no alcohol for at least 48 hours , and ( 3 ) no intense physical activity on the previous day .
subjects were organized into self - help groups by area of residence to facilitate followup and for active prevention support once the followup study would be over .
apart from contacts for formal followup data collection , self - help groups were encouraged to meet every three months for weight and blood pressure checks , and for standard general health advice .
anthropometric and blood pressure data that were collected during these meetings were not used in the followup study reported here .
anthropometric variables included body weight , height , and wc that were measured according to standard procedures .
it was measured to the nearest 0.1  cm at the midpoint between the lower rib margin and the iliac crest while subjects were standing and breathing normally .
we used a flexible nonstretch measuring tape at baseline survey and at the first followup .
a flexible nonstretch measuring tape ( gulick ) equipped with an estimator of the applied tension during measurement was used in the last followup .
two measures of wc were taken for each subject and the mean of the two readings was used in the analyses .
generic cutoff values for ao ( 80 and 94  cm for women and men , resp . ) were used , as recently recommended by several organizations for sub - saharan africans , in the absence of specific values .
body weight was measured on subjects in fasting with light clothing and without shoes to the nearest 0.1  kg using a mechanical scale that had maximum capacity of 150  kg ( seca , germany ) .
height was measured once at baseline to the nearest 0.1  cm with a commercial stadiometer ( seca , germany ) .
body mass index ( bmis ) cutoffs for underweight ( < 18.5 ) , overweight ( 2529.9 ) , and obesity ( 30 ) were as defined by who .
systolic and diastolic blood pressure was measured on the right arm of seated subjects after a 10-minute rest .
the interval of time between the first and the second reading was at least 20 minutes .
high blood pressure was defined as systolic blood pressure ( sbp ) 130  mmhg and or diastolic blood pressure ( dbp ) 85  mmhg .
blood samples were collected in the morning after a 12-hour overnight fast and were centrifuged within two hours in the biochemistry laboratory of the institute of applied biomedical sciences in cotonou . using standard enzymatic laboratory methods , fasting glycemia , and serum concentrations of total cholesterol ,
the ratio of total cholesterol / hdl - c ( tc / hdl - c ) was computed .
abnormal values were defined as : elevated triglycerides ( > 1.70  mmol / l ) ; high fasting glycemia ( 5.6 
fasting insulin was assayed using elisa method with ibl kits ( ibl , hamburg ) .
insulin resistance cutoff was the 75th centile of homa - ir ( homeostasis model assessment , insulin resistance ) in the whole sample of subjects .
the selected cutoffs for high tc / hdl - c were 4 for men and 5 for women .
cmr factors considered in the study along with ao according to wc or high bmi ( overweight / obesity ) were high blood pressure , high fasting glycemia , insulin resistance ( based on homa - ir ) , low hdl - c , high tc / hdl - c , and high triglycerides . in counting cmr factors ,
high fasting glycemia or ( newly diagnosed ) diabetes , or insulin resistance were considered as one risk factor .
dyslipidemia as one risk factor was defined as low hdl - c , high tc / hdl - c , or high triglyceride concentration .
ses was assessed at baseline using a household amenity score as proxy of household income , much like in several demographic and health surveys in africa .
the items include type of latrine ; paid domestic help ; ownership of land , motorcycle , car , television , mobile phone , land line phone , and refrigerator ; electricity , running water in the house ; type of fuel used for cooking ; wall and floor materials .
the ses score was computed separately in each site and tertiles were used in analyses .
dietary intake was computed at baseline on the basis of two or three nonconsecutive 24-hour food recalls conducted over an average period of one month .
diet quality was appraised with several scores including a micronutrient adequacy score which was significantly associated with cmr in the cross - sectional study ( unpublished data ) and is therefore used in the present study . the micronutrient score was based on adequacy of intake of 14 micronutrients ( vitamins a , b6 , b12 , c , and e , thiamine , riboflavin , niacin , pantothenic acid , folic acid , magnesium , calcium , iron , and zinc ) according to who / fao recommended dietary intakes for age and sex .
alcohol consumption is expressed in the present study as mean quantity of pure alcohol per day . regarding smoking , we distinguished three categories : smokers , ex - smokers , and nonsmokers . for alcohol and tobacco ,
participants were asked about all their previous day 's activities , from the time they got up to the moment they went to bed .
time spent in bed , in various modes of transportation , for main and secondary occupations , for house chores , and for leisure activities was computed from the daily estimated schedule .
the intensity level of each activity was estimated in metabolic equivalents ( mets ) . based on who guidelines for the prevention of chronic diseases , we classified subjects as active ( 3  met , 30  min / day ) and inactive ( 3  met , < 30  min or <3  met , any duration ) .
the differences in cmr factors at baseline and at last followup according to anthropometric status were assessed using chi test .
the incidence rate was computed as the number of new cases during the four years divided by the number of subjects without the risk factor at baseline .
the relative ( rr ) risk of developing one or the other cmr factor during the course of the followup was assessed using multiple logistic regression models while controlling for baseline age , diet ( micronutrient intake adequacy score ) , and lifestyle ( alcohol consumption and physical activity ) , as well as wc change between t0 and t2 .
the study was approved by the ethics committee of the faculty of medicine ( university of montreal ) and by the ministry of health in benin . written informed consent was obtained from each participant before enrolment .
the participants were all informed individually of their blood pressure and the results of laboratory tests .
out of 622 eligible subjects , a total of 541 completed the study , giving a response rate of 86.9% .
the participation rates were 76.7% ( 415 out of 541 ) in first followup and 76.9% ( 416 out of 541 ) in the second followup ; 67.7% ( 366 out of 541 ) had complete followup data .
baseline characteristics of subjects who attended both followups and those who missed one or the other ( table 1 ) were not significantly different except for age , anthropometric status ( in men only ) , and place of residence .
average age was higher by roughly two years in men and women with complete data compared to those with incomplete data . a lower proportion of subjects were available for followup in the large city than other locations .
obesity - related parameters were significantly higher in men with complete followup than in those with incomplete data .
socioeconomic status , diet , and lifestyle were not significantly different in the two groups , however .
statistical analyses were performed on subjects with complete data ( n = 366 ) ( figure 1 ) . at baseline ,
indeed , one man for three women had ao . similarly , one man for two women was obese or overweight based on bmi . 

table 2 gives the prevalence rate of cmr factors at baseline according to anthropometric status of subjects .
initial prevalence of cmr factors was generally higher in obese or overweight subjects compared to those with normal anthropometric status at onset of study , whether on the basis of wc or bmi .
the prevalence of hypertriglyceridemia and fasting hyperglycemia was low and not significantly different in obese and nonobese subjects .
in ao subjects , only 16.6% of women and 6.2% of men were free from other cmr factors .
similarly , only 19% of women and 13.6% of men who were overweight / obese ( bmi > 25 ) at baseline presented no additional cmr factor . in both men and women , the proportion of subjects without any of the cmr factors considered was significantly higher in the nonobese or overweight .
the difference was particularly marked in men , with at least a threefold increase in the proportion of cmr - free subjects among the nonobese or overweight . 

table 3 shows that the prevalence of most cmr factors increased significantly over the four - year followup in both men and women , even hypertriglyceridemia which was low and remained so . of note
, subjects who went on medical treatment for high blood pressure ( n = 30 ) are included in the prevalence figures , and those being treated for diabetes with insulin or oral hypoglycemiants ( n = 3 ) are included in  high fasting glycemia  and  insulin resistance . 
it is reminded that at baseline , already diagnosed cases of hypertension or diabetes were excluded from the cohort .
there was over the four - years a significant decrease of high blood pressure prevalence .
the rate of general overweight / obesity tended to increase , and that of ao increased significantly , but only in women . in men , only an upward trend for overweight / obesity was observed .  
figure 2 provides more detail on the evolution of bmi and wc status . in women ,
overall and abdominal obesity increased significantly . in men , overall obesity and ao rates remained low over the followup period ; a nonsignificant upward trend was only observed for overweight , and not for overall obesity .   compared to the nonobese , ao subjects exhibited a significantly higher incidence rate of high tc / hdl - c ( p  = 0.002 ) , as shown in table 4 .
the incidence rate of insulin resistance tended to be higher in ao subjects ( p  = 0.051 ) .
subjects who had to go onto medical treatment for high blood pressure or diabetes are included in the incidence figures . at the end of the followup period ,
the total number of new cases was 81 for low hdl - c , 58 for high tc / hdl - c , 83 for insulin resistance , 59 for high fasting glycemia , and 11 for diabetes , while there were 19 new cases of high blood pressure , including the subjects under medical treatment ( data not shown ) . in table 5
, the relative risk ( rr ) of onset of cmr factors during the followup period according to obesity status is shown separately for men and women , before and after adjusting for wc changes , age , diet , and lifestyles .
rr could not be computed for other cmr factors because of too small numbers . in women ,
in contrast , in men , the rr of onset of dyslipidemia was three- to four - fold in subjects exhibiting initial ao compared to the nonobese in the nonadjusted model .
controlling for wc changes and initial diet and lifestyle profile further increased the likelihood of dyslipidemia up to seven times .
the study examined the evolution of cardiometabolic risk ( cmr ) factors according to baseline obesity status , while controlling for confounding factors , as well as for obesity change over the followup period .
we had to combine overweight and overall obesity ( bmi  25 ) because of the small number of men with overall obesity ( bmi  30 ) .
furthermore , results were examined primarily for ao using wc cutoffs as suggested by several organizations ( in an attempt to harmonize the definition of mets ) in the absence of specific values for sub - saharan africans , since ao is considered to be associated with higher risk than general obesity .
however , we observed the same trends when considering overweight / obesity based on bmi instead of ao based on wc ( data not shown ) .
one practical implication is that until specific cutoff points for obesity ( general or abdominal ) against chronic disease endpoints are validated in sub - saharans africans , bmi cutoff for overweight and wc cutoffs of 80  cm ( for women ) and 94  cm ( for men ) for ao might be used interchangeably for screening .  
only 16.6% of women with abdominal obesity at baseline had no other cmr factor , and the proportion was still lower among ao men ( 6.2% ) .
nonetheless , we were able to verify whether baseline ao was associated with a more adverse evolution of other cmr factors , at least during a followup period of four years .  
the cmr factors studied , except for the high tc / hdl - c ratio , are usually examined together as the metabolic syndrome ( mets ) , which is a clustering of some of the following : high blood pressure , dysglycemia , dyslipoproteinemia , and abdominal obesity . however , as we wanted to isolate obesity and assess its impact on the evolution of other cmr factors , we considered the risk factors separately .
another justification for not collapsing the cmr factors into the mets is that mets phenotypes vary widely according to race - ethnicity .
high triglyceride concentrations , for instance , are not common among africans while hypertension is highly prevalent . in populations at risk for cvd , it was reported that tc / hdl - c ratio would identify more at - risk subjects than framingham risk scores .
furthermore , tc / hdl - c showed the largest area under the curve of homa - ir compared with other lipid components or ratios in indian diabetics .
control variables were those found to be significantly associated with one or the other cmr factor in the baseline study : age , physical activity , alcohol consumption , and dietary micronutrient adequacy as the only significant diet quality score [ 18 , 19 , 24 , 32 ] .  
the study confirmed that obesity , which is widespread among women , was associated with elevated cmr in this sub - saharan population . except for high blood pressure ,
an upward trend of cmr markers was observed over the four - year followup both in obese and non obese individuals .
the incidence of high tc / hdl - c was significantly higher in ao than nonobese subjects .
the significantly higher relative risk of onset of dyslipoproteinemia in ao men ( not significant in women ) over the followup period , even in the adjusted model , suggests that ao as currently defined using nonspecific cutoffs may be associated with higher cmr in men than women .
this is consistent with a recent cross - sectional study in senegal that reported less favourable cmr profiles in men than women in general , with lower hdl - c concentrations . according to a recent review ,
higher hdl - c may be considered a gender - specific protective factor in women . however
, longitudinal studies of longer duration and in larger cohorts , using not only cmr factors but also disease end points would be required to confirm the findings .
because of the small number of new cases of high blood pressure and high hypertriglyceridemia , for instance , we were unable to perform logistic regression on these risk factors .  
the higher observed prevalence of obesity among women than men is consistent with other studies in sub - saharan africa .
this may be partly explained by the on - going nutrition transition process in dcs with major shifts in diet and lifestyle patterns under the influence of urbanization , globalization , and economic growth [ 36 , 37 ] . the observed downward trend for wc among obese subjects , at least in women , whereas the trend was positive in the nonobese , may reflect this nutrition transition process , with normal subjects progressively moving towards more abdominal adiposity ; or else , these opposite trends reflect the phenomenon of regression to the mean .  
in our study , the baseline proportion of insulin - resistant subjects was significantly higher in obese compared with non obese whereas no difference was observed for high fasting glycemia .
furthermore , the incidence of hyperglycemia was not different in obese and non obese while the incidence of insulin resistance tended to be higher in the obese .
indeed , under normal conditions , the pancreatic islet -cells increase insulin release to overcome the reduced efficacy of insulin action , thereby maintaining normal glucose tolerance . for obesity and insulin resistance to be associated with high fasting glycemia , -cells must be unable to compensate fully for decreased insulin sensitivity .
several studies reported the association of obesity and insulin resistance in obese africans based on bmi , waist / hip ratio , or wc [ 4042 ] .
however , the duration of obesity is reportedly critical [ 43 , 44 ] , but we did not have this information .  
low hdl - c was the most prevalent cmr factor in the last followup , in both men and women ( 47.3% and 30.3% , resp . ) .
concurrently , the incidence rate of high tc / hdl - c was markedly higher in obese subjects .
this is consistent with studies showing that low hdl - c is a major dyslipoproteinemia phenotype in obese africans [ 33 , 45 ] .
in fact , studies show a gradual decrease in hdl - c levels in africa , over the last three decades [ 4547 ] .
this decreasing trend in hdl - c levels can be attributed to the urbanization of african populations and changes in diet and physical activity .
as suggested by some authors , a longer life expectancy and more access to abundant food may contribute to increased prevalence of low hdl - c in developing countries .  
the downward trend of blood pressure means as observed in our study over four years , even excluding subjects under treatment for hypertension , can not be fully explained , although some authors reported a weak link between obesity and high blood pressure in africans [ 40 , 49 ] while others observed an association , for instance in rural communities in south nigeria .
several cross - sectional studies in non - africans reported the deleterious effect of obesity on blood pressure [ 51 , 52 ] .
the etiologic mechanism linking obesity and hypertension is the stimulation of sympathetic tone and the activation of the renin - angiotensin - aldosterone system mediated by adipocyte hormones .
since blacks had less visceral fat , this relationship between obesity and blood pressure may be weaker than in caucasians .
another possible explanation for the reduction of mean blood pressure during the study is that individuals became more aware of their blood pressure as it was checked in the self - help groups , making them more receptive to the general health advice given to them .
however , when controlling for participation in group meetings , the results were unchanged ( data not shown ) so that self - help groups may not be considered as confounders .
nevertheless , this does not exclude that subjects adopted a more preventive diet and lifestyle , which can not be verified .
we can not totally exclude either technical error measurements since blood pressure was not measured by the same medical team throughout the study , although measurement techniques were standardized .  
first , only 68% of baseline participants had complete data and were included in the analysis , since significant differences in age , anthropometric status ( bmi and wc ) and location were observed between subjects lost to followup and those with complete followup at t1 and t2
secondly , the relatively short followup period did not allow collecting sufficient data on hard endpoints ( incidence of diabetes , cvd , or cancer ) to fully assess the risk associated with obesity status .
thirdly , we did not have information on whether weight loss , when it occurred , was intentional or not .
finally , the study was only conducted in the southern part of benin and therefore , extrapolation of the findings to other population groups requires caution .
these limitations notwithstanding , the study has major strengths , including that it is the first prospective population - based study in sub - saharan africa which addresses the issue of cardiometabolic risk factor changes according to ao .
additionally , we were able to control for several lifestyle variables in order to explore the independent effects of baseline ao status in men and women .
abdominal obesity as defined by high waist circumference ( generic cutoffs suggested for sub - saharan africans ) was associated with higher cmr at baseline and over the four - year followup period , except for high blood pressure , in initially apparently healthy benin adults . based on our findings
, there was a worsening trend of cmr factors during the followup period among the abdominally obese subjects , and particularly for cholesterol profile among men .
the lack of association between baseline obesity and blood pressure changes suggests that the effect of obesity on the latter may not be important in the study population .
larger longitudinal studies of longer duration in sub - saharan africans are needed to confirm our findings .
 the study examined whether abdominal obesity ( ao ) according to waist circumference was associated with more unfavourable changes in other cardiometabolic risk ( cmr ) factors in sub - saharan africans . 
 the study included 541 randomly selected and apparently healthy subjects ( 50% women ) aged 2560 years . 
 complete data at baseline , 24 , and 48 months later was available in 366 subjects . 
 ao was associated with higher cmr at baseline and over the follow - up period , except for high blood pressure 
 . a significantly higher incidence of high ratio of total cholesterol  :  hdl - cholesterol ( tc / hdl - c ) was associated with ao . 
 controlling for wc changes , age , baseline diet , and lifestyles , the relative risk ( rr ) of low hdl - c and high tc / hdl - c was 3.2 ( 95% ci 1.069.61 ) and 7.4 ( 95% ci 2.0125.79 ) , respectively , in ao men ; the rr was not significant in women . over a four - year period , ao 
 therefore appeared associated with an adverse evolution of cholesterolemia in the study population . 
1. Introduction
2. Methods and Materials
3. Results
4. Discussion 
5. Conclusion 