Background
The prevalence of obesity (BMI ≥ 30 kg/m
2) worldwide is continuously rising and is a global public health concern [
1,
2]. Obesity peaks in middle and older age but is becoming more common at a younger age [
2]. A high prevalence of overweight (BMI ≥ 25 kg/m2) (25.3 %) and obesity (21.7 %) is also seen in South African females aged 18 to 24 years [
3]. It has been well documented that female students, especially those in their first year at tertiary education institutions, are prone to gaining weight [
4]. Excessive body weight i.e. being overweight or obese or having central obesity is associated with serious health consequences [
5,
6].
The rise in overweight and obesity has contributed to increasing numbers of people within populations who need to, and attempt to lose weight [
7]. This may also be the case with university students [
8,
9]. Unfortunately, the reality for most dieters is that weight-loss attempts have a poor success rate and the minority who do succeed in losing weight regain most of the lost weight within a few years [
10].
It further needs to be considered that in Western society young females, including university students, often aim for the thin beauty ideal, leading them to try and attain weight goals that are unrealistically low [
11‐
14]. To achieve this desired body weight they may be using dieting strategies that are unhealthy (e.g., fasting) or extreme (e.g., laxatives) [
12,
15,
16]. Extreme concern with weight, dieting and body perception can result in high-risk behaviours such as restrictive and disordered eating, binging, purging and ultimately eating disorders [
8,
15]. The high prevalence of these disorders in adolescent and young adult females is a particular concern [
17,
18].
Within the South African context a further concern is that obese women, specifically black women, may be unaware of the need for weight loss for health purposes [
19]. Research carried out in South Africa and other countries shows that black females are generally more tolerant of a larger body size and that this may be socially more desirable, [
19‐
21]. A number of studies have also shown that overweight black women are more likely than white women to perceive themselves as being normal weight [
12,
22,
23]. These findings provide important insights in the lack of awareness of black women in their personal weight management needs. Research on black South African female students and adult women does, however, show that acculturation to Western body shape and size ideals may be taking place [
12,
24] and that dieting is not uncommon among young black women [
12].
The aims of this cross-sectional survey were to investigate the weight-loss strategies used by female university students at select South African Universities who attempted weight loss over the year preceding the study (aim 1) and to compare weight related characteristics between dieters and non-dieters (aim 2). These insights will contribute to development of effective intervention strategies and public health messages to promote healthy weight management in this vulnerable population.
Discussion
This research set out to investigate weight loss strategies used by female students and to compare weight management characteristics between dieters and non-dieters. Dieting during the past year was found to be prevalent among normal weight, overweight and obese students. Weight loss strategies used were mostly healthy, although unhealthy and extreme strategies were also used. Significant differences in weight, BMI, body weight perception and satisfaction, weight management related environmental influences, physical activity, meal pattern and food choices between dieters and non-dieters were evident.
Dieters and non-dieters were of equal age, with 24.1 % of dieters being overweight and 5.6 % obese, while 11.4 % of the non-dieters were overweight and none obese. For both groups these figures are below the national average reported for 15 to 24 year old females, namely 25.3 % being overweight and 21.7 % obese [
3]. For dieters the proportion is higher than the 10 % white female students reported to be overweight and 0.8 % to be obese by Cilliers et al. [
27], and in line with the 22.1 % black female students reported to be overweight/obese by Steyn et al. [
31].
A history of dieting during the past year was present in almost two thirds of the total group of students. It is possible that the recruitment strategy, namely asking students whether they would be interested in participating in a study on the “dieting strategies of students”, created the perception that the study was focused on dieters only. However, dieting in the past year or two has been found to be a common phenomenon among female students at tertiary institutions in South Africa and in other countries. Data for South Africa reported that 55.3 % of white female students had attempted weight loss in the previous year [
28], while the proportion was 42 % in black female students over the past two years [
12]. Studies carried out in several other countries have also reported that a high proportion of young adult females, including many who have a normal weight, are trying to lose weight [
25,
32,
33]. For example, Fayet et al. [
34] reported a prevalence of 43 % for female Australian students, Lee [
35] 41 % for non-overweight Korean female adolescents, and Schembre et al. [
36] 76 % for white and 50 % for Native Hawaiian female students. This suggests that our sample was reasonably representative of female students, though there may have been some degree of over-sampling of dieters.
The most commonly (>75 % of dieters) used weight-loss methods were healthy, namely increasing exercise, increasing intake of fruit and vegetables, and reduced consumption of fat-rich foods, sweets and sugar-sweetened beverages. Unhealthy weight-loss methods, such as eating little food, skipping meals and fasting, were also commonly used (from 37 % to 13 % of dieters), which is in accordance with results from other studies, with eating less food and skipping meals generally being more commonly used than fasting [
8,
12,
15,
25,
37]. Extreme weight loss strategies were also used by students in this study, but the prevalence was less than 5 % for each. The prevalence of using laxatives found in our study (4.1 %) is in line with previous research in female students, where it was reported to range from 1.6 % [
8] to 15 % [
12]. The prevalence of vomiting was found to be 3.4 % in our student sample, which is also similar to the prevalence of use of this strategy in other groups of students. For example, Malinauskas et al. [
25] found that 4 % to 6 % of female college students used vomiting as a weight-loss method. Similar results were found by Neumark-Sztainer and Hannan [
15] (6.8 %) and Alvarenga et al. [
17] (3.3 %). Senekal et al. [
12] reported that 11.7 % of their sample of South African black female students indicated that they used vomiting as a weight loss method.
Weight-loss products were most likely to be used in spring or summer, leaving room for speculation that dieting and use of these products in female students may be linked to getting in “form” for the summer period. The most commonly used weight-loss products were in descending order (≤11 % of dieters): Herbex, Herbalife, GI Lean products, Hoodia, USN products and CLA products. Senekal et al. [
12] reported similar proportions of use of diet formulae/milkshakes and appetite suppressants by black South African female students. The use of Herbex was significantly higher in the overweight/obese sub-group. Use of commercial weight loss products may reflect increased pressure felt by overweight/obese individuals to lose weight. However, with very few exceptions these weight loss products suffer from a serious lack of supporting evidence [
38,
39].
Comparison of weight related characteristics between dieters and non-dieters showed that the race profile was similar, with just more than two thirds of black participants being dieters. This may reflect acculturation in black female students, namely increased acceptance of the Western thin beauty ideal. These results confirm the notion of acculturation in black female students and women as discussed by Senekal et al. [
12] and Puoane et al. [
19,
24].
Dieters had a significantly higher BMI and prevalence of overweight and obesity than non-dieters. However, it is important to note that the weight of two thirds of the dieters was in the normal range. This suggests that dieters may have been successful with their weight loss attempt(s) or that they may desire to have a weight at the low end of normal or in the underweight range. Conversely, not all overweight young women seem motivated to lose weight as a number of the non-dieters in this study were overweight, which may be linked to the acceptance of a larger body weight in certain cultures [
19‐
21]. Dieters in this study were more prone than non-dieters to see themselves as heavier than their actual weight, with normal weight students who viewed themselves as “too chubby” being approximately three times higher among dieters than non-dieters. Dieters were also less satisfied with their bodies as they were significantly more likely to be unsatisfied with their weight, waist, hips, legs and arms than non-dieters. Consistent with our findings, especially for the dieters, other studies have also observed that many young adult women have a distorted body-image [
27,
33,
34,
40]. These results emphasize the possibility that normal-weight students may be engaging in unnecessary weight-reduction practices to ‘normalise’ their weight, increasing the risk for development of eating disorders. On the other hand, overweight students in both groups who perceive to have a normal weight, are at increased risk of development of obesity as they will not be motivated to lose weight.
Sources of weight management information and pressure to lose weight were investigated as weight management-related environmental characteristics of students. Dieters were significantly more likely to have used the Internet, friends, family and magazines (in descending order of use by dieters) than non-dieters for weight-management related information. Use of the television, a nutrition expert, a physician or pharmacist (in descending order of use by both groups), did not differ between dieters and non-dieters. This is in line with the findings of Steele and Senekal [
41], namely that South African university students use family and friends, doctors and advertising as main sources of information on the need for dietary supplementation. Although dietitians and nutritionists are the experts in nutrition, students seem to lean towards informal and easily accessible sources of nutrition and weight management related information, which may not necessarily be evidence based. However, the potential advantages of using the Internet as information source should not be completely discounted. In their qualitative work in 11-to-19 year-old adolescents Gray et al. [
42] identified such advantages, namely: avoiding a visit to a health professional, information being generally current as most websites are regularly updated (more so than is the case with print media), allowing an individual to search in ways unconstrained by place and time, being able to print and store information, personalization through feedback loops and facilitating the use of a social support network.
Pressure to lose weight from mothers, siblings and female friends, and to a lesser extent from the father and husbands/partners was experienced by both dieters and non-dieters. However, dieters were significantly more likely than non-dieters to have experienced pressure from all the mentioned individuals. These findings are similar to those of McCabe and Riciardelli [
43] in 14-year-old girls, namely that the strongest influences on weight-loss decisions were mothers and best female friends, with much less influence coming from fathers or the media. This is especially important considering the findings by Peterson et al. ([
13], p. 636) that: “Maternal pressure to lose weight and to be attractive appeared to have a strong influence on adolescents’ view of their physical appearance. These nonbehavioral, psychological influences may be firmly established from mother input, perhaps from an early age, to such an extent that even the young person’s friends are unable to affect them.”
Dieters in our sample spent almost three times more time doing vigorous physical activity (sport participation or exercise) while the time spent doing moderate physical activity (e.g. walking) was the same. Dieters were also significantly more likely to perceive themselves to be more active than their peers. The current guidelines for physical activity in the United States of America are that adults should spend at least 150 min per week engaged in moderate-intensity or 75 min per week of vigorous-intensity aerobic physical activity [
44]. When time spent in vigorous and moderate physical activity is summed in each of the two groups, it is evident that both groups met the physical activity requirements for health. The higher level of participation in vigorous physical activity by dieters may be the result of increased awareness of the importance of physical activity in weight control, as increased physical activity was one of the dieting strategies most commonly mentioned by these students.
Dieters made unhealthy food choices that included energy dense snacks and drinks, refined carbohydrates and high fat foods significantly less often, and healthy food choices that included fruit/vegetables, wheat fibre and legumes and low-fat protein-rich foods significantly more often than non-dieters. Dieters may have been more aware of healthy food choices, as is reflected in the fact that increased intake of fruit/vegetables and decreased intake of energy-dense foods were very commonly mentioned as weight-loss strategies. However, it needs to be noted that neither dieters nor non-dieters met the South African Food-Based Dietary Guideline (SAFBDG) [
45] for eating five or more fruits and vegetables (combined) per day. This is in line with the finding by Mckize et al. [
46] who conducted a review of dietary surveys in the adult South African population, that two of the three most commonly deficient food groups are fruit and vegetables, with dairy being the third (dairy was not assessed as an distinct group in this study). Further support for this dietary risk in adult South Africans comes from the SANHANES [
3], where it was found that only 4.5 % of the sample consumed four or more fruits and vegetables (combined) per day. Results show that students in our study may also not be meeting the guideline “eat sugar and fat sparingly,” as unhealthy (energy-dense) food choices were made either equally frequent (dieters) or more frequently (non-dieters) than healthy food choices. The fact that a higher frequency of high-fat food choices increased the risk for overweight/obesity in our sample (risk increased by 40 % for each additional time per day a high-fat food item was consumed) confirms the obesity risk denoted by the consumption of energy-dense foods.
The meal pattern of dieters and non-dieters in our study is in line with the SAFBDG recommendation that food intake should be spread throughout the day in the form of regular small meals [
45]. Dieters consumed breakfast significantly more frequently than non-dieters, possibly also reflecting better awareness of healthy eating guidelines. It is interesting to note that a lower frequency of intake of a mid-morning snack predicted a higher BMI, supporting the notion that a pattern of more frequent, smaller meals supports achieving and/or maintaining a healthy weight.
Black students in our study were found to be at increased risk for a higher BMI and being overweight/obese when compared to white and coloured/Indian students. This is in line with data from SANHANES, namely that the prevalence of overweight/obesity is highest in black women of varying ages [
3]. Further predictors for a high BMI and increased risk for overweight/obesity found in our study include not being satisfied with one’s waist and currently perceiving one as being too “chubby”, which could be correct or the result of a distorted body image. Attempted weight loss during the past year predicted BMI, but not risk for overweight/obesity, implying that dieting increases with increasing BMI, but that those who diet are not necessarily overweight/obese. This finding supports the notion that the decision to diet may not necessarily be prompted by being overweight/obese and the need for improved health, but rather by the wish to be thin consistent with the common Western ideal of beauty.
The findings of this research need to be viewed in the context of the study limitations. These include the cross-sectional design, the convenience sample drawn from select South African universities, which is not representative of the female student population in South Africa, and the use of a self-administered questionnaire, which leaves room for error in the responses given. Furthermore, more comprehensive physical activity and dietary intake assessment may have provided more in depth insights in the differences between dieters and non-dieters for these variables.
Bearing these limitations in mind it can be concluded that the findings reported here show that weight-loss attempts may be highly prevalent in female students regardless of weight status and race. Although healthy weight loss strategies seem to be commonly used, unhealthy and extreme methods, including a variety of commercial weight loss products, are also used. When compared to non-dieters, dieters are characterized by a higher BMI (although not necessarily in the overweight/obese range); a higher prevalence of overweight and obesity (although the majority are normal weight); body image distortions (normal weight students perceiving themselves to be overweight, although some overweight students perceive themselves to be normal weight); dissatisfaction with weight, arms, legs, hips and stomach; pressure experienced from especially mothers, friends and siblings to lose weight; use of the Internet, friends, family and magazines for weight-management information and a healthier life-style i.e. higher levels of physical activity that meet the physical activity guidelines and a higher frequency of healthy and lower frequency of unhealthy food choices, although not yet meeting the FBDG. Finally, weight loss attempts during the past year predict BMI, but not risk for overweight/obesity, implying that dieting prevalence increases with increasing BMI, but those who diet are not necessarily overweight/obese.
Healthy weight management, whether it involves weight gain for those who are underweight, prevention of weight gain for those who are normal weight, weight loss or prevention of further weight gain for those who are overweight/obese or weight maintenance for those who have lost weight, is core to ensuring optimal health and prevention of eating disorders, non-communicable diseases [
11]. Female students are the mothers and caregivers of tomorrow and their weight management practices from pregnancy onwards hold strong potential to set the stage for the weight and ultimately the health of future generations.