Weight patterns and perceptions among female university students of Karachi: a cross sectional study

Body weight and its perception is an important aspect of health and constitute a significant role in physical and mental well-being. The World Health Organization (WHO) uses the body mass index (BMI) to categorize weight status. The BMI is calculated as the weight in kilograms divided by the square of the height in meters (kg/m2). A BMI <18.5 is considered underweight and >25 overweight. Falling between these ranges is normal weight. Based on this definition, the WHO estimates more than one billion adults to be overweight and three hundred million of them to be obese [1].Obesity is a well-known risk factor for cardiovascular diseases [2], diabetes [3] and decreased life expectancy [4]. Much less investigated and even less discussed is being underweight. Underweight people are at risk for irregular menstruation [5], weak immunity [6] and osteoporosis [7].

Current prevalence of different body weights show varying trends in different parts of the world. The majority of these studies are from the developed world. A study of 2032 high school male and female students across the U.S., grades 9 through 12, found 1.5% of students to be underweight and 51.2% and 47.4% to be normal weight and overweight respectively [8]. Another study, focused on 360 first year female university students in South Africa found 7.2% to be underweight and 10% overweight [9].

In Pakistan, few studies are available to ascertain the prevalence of weight status. One study of 284 schoolchildren in Karachi found that 52% were underweight [10]. The results are strikingly different from the studies elsewhere although effects of age-group have to be kept in mind. In Pakistan, socio-economic level plays a major role in weight status and is a focus of the study done previously [11]. No studies of weight perception can be found despite the fact that it influences eating habits and other aspects of mental health in Pakistan [12].

Regardless of whether a person is underweight, normal or overweight, weight perception is an important determinant of nutritional habits and weight management [10]. Discrepancies between true weight and weight perception can have serious implications. Normal or underweight adolescents, who perceive themselves as overweight, are at risk for eating disorders such as anorexia nervosa [13].

Conversely, overweight adolescents perceiving otherwise are unlikely to control diet or engage in physical activity [14]. Aberrant weight perceptions can lead to risky behaviour [15] such as smoking cigarettes and skipping breakfast. Underweight women are more likely to have poorer psychological health than normal weight women. In contrast, overweight and obese women are more likely to have poor health related behaviours and lack of internal locus of control compared with normal weight women [16]. The psychosocial, psychological and behavioural implications are significant.

Females are sensitive to the effects of weight perception [17] and studies have shown that they perceive weight incorrectly [18–21]. The problems with weight and weight perception are universal but greatly influenced by social norms. Current studies are heavily concentrated in the developed world. More widespread studies are needed to properly assess the importance of the patterns and perceptions of weight status. There is a lack of information from the South Asian population. Preventive strategies, dealing with the psychological risk at an individual level and body norms in media can be addressed. It is important to study health behaviour of young adults because the rapidly changing conditions in the world are bringing about changes in behaviour, and behaviour formed in the second decade of life has lasting implications for the individual in particular and the public health in general [22]. This study was done to explore the relationships between body weight perceptions, actual body mass index and weight control behaviours among the female students of Karachi, Pakistan.

Our socio-demographics revealed that our study population was mostly unmarried, healthy female students. Our mean BMI of 20.89 ± 1.49 falls in line with other studies performed on similar target populations in Pakistan [26, 27]. Based on this result, it can be asserted that although we had a convenience sampling, the similarity in mean BMI with other studies counters the presence of any strong bias in our results. The breakup of our sample into weight categories according to the WHO Asian criterion showed that just more than half of our sample was of normal weight with an approximately equal proportion being underweight and overweight; underweight being slightly higher. This distribution is similar to the one reported in other studies performed on university students in Pakistan [27, 28] but is strikingly different to results from studies in the west. The proportion of underweight females in similar target populations from the west is much lower and varies from 3 - 18% [8, 9, 16]. The proportion of underweight female students in our study (27.2%) is similar to other studies from Pakistan [27, 28] but higher to other Asian countries such as India [29] and Lebanon [30], where the underweight females were found to be 12.1% and 12.4% respectively. Studies from Pakistan that comment on the underweight status of young female adults are scarce. Regarding proportions of overweight, our results (21.3%) fall in line with studies from other countries such as America, South Africa and Swedan [8, 9, 16] in which overweight ranges from approximately 10 - 25%. This suggests that the difference in prevalence of overweight status from east to west is much less as compared to the difference in underweight status. In all studies, the normal weight status follows similar trends in proportion.

The higher proportion of underweight status is of concern as it put females at risk of many health issues i.e. menstrual irregularitites, osteoporosis and weak immunity [5–7]. Previous research on weight perception has shown that female students do not have a realistic perception of their actual weight [18–21]. One third of our study population misclassified their weight which mirrors this assertion and has been shown in other studies [20]. Approximately half of the underweight females in our study perceived themselves as normal which implies that underweight students may not want to gain weight but would prefer to remain underweight. The same concept applies to the normal weight students who perceive themselves as overweight as they may attempt to unnecessarily reduce weight to meet their inaccurate normal standards [31]. The tendency of underweight females to perceive themselves as normal is frequently observed [8] but the emphasis usually shifts to normal weight females perceiving themselves as overweight. These normal weight females may undertake unnecessary weight loss which is a more apparent issue than the risks of remaining underweight. The more significant finding was the perception of normal weight by underweight females which may have its roots in a wider social and cultural acceptance of thinness.

Our results show that the normal weight females had a fair level of accuracy in weight perception. We found that overweight females had the most accurate perception of weight and this has been shown to be the case in other studies too [32]. Our results indicate that the highest weight satisfaction was seen in the underweight group. This is potentially dangerous as these female students are less motivated to normalize their weight, which was seen in the high percentage of them doing nothing about their weight. Reassuringly, very few underweight females were actively trying to lose weight but on the other hand. This shows the poor weight related perceptions in the underweight group. A fairly large part of the normal and overweight groups were not satisfied with their weights which have also been reported for female students in the UK [33] and undergraduates in the US [34]. The high level of dissatisfaction among the normal group is worrisome as a quarter of them still want to lose weight. The high level of dissatisfaction and active weight loss practices among the overweight group are justified. However, it is important to emphasize realistic weight loss goals and acceptable weight loss practices. Skipping breakfast and actively avoiding foods was seen across the board with a tendency to increase with BMI. These unhealthy practices have been associated with greater levels of fatigue [35], increased weight gain [36], and irregular menstrual cycles [37].

A unique finding in our study is the assessment of weight goals in the perceived weight categories. The results are very similar to the weight goals of the measured weight categories. This indicates that although many studies report weight perception as a better indicator of weight management behaviour [8, 9], it seems that this is not applicable to our population. It appears from the results that despite weight perception being inaccurate overall, the weight goals did not differ significantly between perceived and measured weight groups. Self-perception of weight did not supersede true weight in influencing weight goals. Further studies should be done to evaluate this trend and to determine the possible other factors, such as socio-cultural pressures or lack of weight-related knowledge, that may be responsible for poor weight goals. Comparing the mean BSQ score of our study (75.34) with others (85.0 to 96.3) [38] we encountered a slightly lower value, portraying the students being less concerned about their body shape overall. Correlating weight subgroups with the mean BSQ scores however, we did find an increase in mean BSQ scores from underweight to overweight students. This is consistent with other studies which show a positive association between mean BSQ scores and BMI [39]. Thus, body shape does concern female students in our population but not as much as other studies have shown.

Trends in physical activity as highlighted by previous studies [38] reveal persons with normal BMI engaging in more exercise than the underweight or overweight groups. We observed a different trend, with low physical activity being the majority in all three weight groups. High levels of physical activity were reported most frequently from the overweight group, where weight dissatisfaction was high and the majority was trying to lose weight. Regardless of the physical activity levels in each subgroup, the majority of our entire sample reported “low” physical activity levels. This indicates a poor prevalence of physical activity among female university students in the city which should be a cause for concern.

Our study has shown that among female university students in Karachi, the prevalence of being underweight is comparatively high. There is a significant misperception of weight, with one third of students misclassifying themselves. Despite the misperception of weight, weight goals were not seen to be very different among measured and perceived weight groups. Health policy makers should implement these findings in future development of health interventions and prevention of depression, social anxiety, low self-esteem and eating disorders among young females due to incorrect perception of weight. If large populations such as university students learned healthy behaviours early in life, this would not only have favourable health outcomes at an individual level, it would also reduce the burden on health services.

Large scale longitudinal studies should be performed in Pakistan dealing with weight perception and specific aspects of dietary habits, body shape and physical activity.