COMMUNITY HEALTH STUDIES VOLUME XI, NUMBER I . 1987

PRESENT AND DESIRED BODY WEIGHTS OF AUSTRALIAN ADULTS: A CAUSE FOR CONCERN?

David Crawford and Anthony Worsley

CSIRO Division of Human Nutrition, Kintore Avenue, Adelaide SA SO00

Abstract Two postal surveys were conducted each on

randomly selected samples of 1,OOO adults drawn from the Adelaide and Melbourne metropolitan areas. Subjects were asked to provide information on their weight, height and desired weight. These variables were used to calculate present body mass index and desired body mass index. The results indicate that 35 per cent of overweight men and 20 per cent of overweight women do not wish to reduce their weight to an ‘acceptable’ level. There is also evidence that 12 to 16 per cent of young adult women wish to achieve or maintain underweight status. The implications of these results are discussed in relation to weight control policies.

Introduction Recent anthropometric surveys have revealed

that approximately 8 per cent of Australian adults can be classified as obese and 32 per cent are overweight.’ Excessive body weight is a major risk factor for several common diseases, including heart disease, hypertension, diabetes mellitus and gallbladder disease.’ Prospective studies have shown that degree of overweight is an independent predictor of increased mortality. For example, the Framingham study showed that relative weight at entry to the study and weight gain as a young adult conveyed increased ,risks of cardiovascular disease that could not be attributed to other risk factors.4 Based on the results of the Framingham study, Bray has estimated that if the U S population were at ideal weight there would be 25 per cent less coronary heart disease and 35 per cent less congestive heart failure and brain infarction.’ The National Health and Medical Research Council of Australia considers a Body Mass Index (weight in kilograms divided by height in metres squared) in the range of 20-25 to be consistent with minimum mortality and least risk of morbidity,(‘ although there is debate over this issue.’-’

The prevalence of overweight amongst Australians, and the health risks associated with overweight, suggest that excessive body weight is a

CRAWFORD & WORSLEY 62

serious public health problem in Australia. Over the past decade a number of health authorities have conducted campaigns and promotions designed to alert the public to the health risks associated with overweight.

Notable examples include the campaigns carried out by the National Heart Foundation, the Australian Nutrition Foundation’s 1985 Nutrition Week, and the Commonwealth’s Dietary Guidelines Policy.lO A 1985 survey of Victorian adults revealed that just over 20 per cent of the population perceive obesity to be the major nutritional problem in Australia. 1 1 Further evidence of public concern about excess body weight is provided by the observations that 17 per cent of men and 22 per cent of women report themselves to be on special diets, many of them for weight control,l and 9 per cent of women are on slimming diets.12 However, there is evidence that health goals are often secondary to fashion and appearance objectives in the quest for thinness.13 Further, the presence of large numbers of overweight and obese people in our community suggests that many individuals may not regard obesity as a major health problem.

The success of a weight control policy depends on accurate information concerning the attitudes and social demographic characteristics of people who do and do not wish to reduce their weight. This study aimed to provide such information.

Subjects and methods This paper presents the results of iwo studies

conducted in Melbourne and Adelaide during 1984. In each study a sample of one thousand adults (minimum age 18 years) was randomly selected from the electoral rolls of the metropolitan area. Both studies involved self-administered questionnaires (copies available from the authors) which were mailed to subjects; non-respondents to the initial mailing receiving up to three reminders over a five week period.

The questionnaires used in the Adelaide and Melbourne studies differed except for a few ‘core’

COMMUNITY HEALTH STUDIES

questions which were concerned with the respondents’ present weight and height, their perceived weight status, their desirec weight, and socio-demographic details such as :;ex, age and occupation. The validity of self-reported height and weight has been established in a number of previous studies in which the lowest correlations between self reports and controlled measures were 0.92 for weight and 0.93 for height.’‘-’’ Generally, these studies showed that women tend to L nderestimate their weight more than men and that the degree of underestimation tends to increase with weight. Other factors, such as age or level of education, were of less importance. Overall the errors in self- reported height and weight tend to be small and self- reports are valid even in groups wherc: poor results might be expected, including the severely overweight and less educated.

Response Rate and Sample C‘haractt..ristics Allowing for persons who were registered with

the Electoral Office but had moved or died, the response rate for the Melbourne study was 76 per cent, and that of the Adelaide study, 78 per cent. The samples were similar in terms of .ige and sex distributions to the adult populations of Melbourne and Adelaide. However, members of some ethnic

communities (e.g. Greek, Italian, Yugoslavian) were under-represented by approximately 40 per cent.

Results Present Weight

Quetelet’s Body Mass Index (BMI) was calculated from the self-reported heights and weights. On the basis of their BMI’s subjects were categorized into one of four weight groups according to a classification described by Bray-’ (Table 1). An inspection of the distribution of these BMI’s across age groups revealed they were similar to those reported for the National Heart Foundation’s 1983 survey in which height and weight were measured.I9

Perception of present weight status The subjects were asked to classify themselves as

either very underweight, slightly underweight, the right weight, slightly overweight or very overweight (Table 2). There are two main points to note here. Firstly, more of the obese perceived themselves to be overweight compared to other BMI groups. Secondly, a number of subjects, particularly women, ‘misclassified’ themselves. For example, almost half of the women of ‘acceptable’ weight regarded themselves as slightly overweight, compared to only 30 per cent of men (Table 2).

TABLE 1:

The proportions of men and women in the four weight groups

Body Mass Adelaide 1984* Melbourne 1984* Australia 1983+ Index (0) (%I (%I

Men Underweight Acceptable weight Overweight Obese

Women Underweight Acceptable weight Overweight Obese

(n=3 16) (1~308) ( n =3 740) <El9 4.4 4.2 3.2

20 25 56.0 66.9 54.0 26 30 33.9 25.3 36.2

2 3 0 5.7 3.6 6.4

( ~ 3 0 2 ) (n=363) ( ~ 3 8 2 4 ) S118 5 .5 4.1 4.0

19 24 64.9 64.5 60.9 25 30 22.9 23.1 26.4

2 3 0 6.6 8.3 8.7

+ Results of National Heart Foundation survey of adults aged 2 5 4 5 years conducted in 6 capital cities in which

* Results of the present study in which BMI was calculated from self-reported height and weight. BMI was calculated from measured height and weight.

CRAWFORD & WORSLEY 63 C O M M U N I T Y HEALTH STUDIES

TABLE 2:

Perception of present weight amongst members of the four weight groups (results expressed as percentages)

Underweight Acceptable Overweight 0 bese weight

Perception of Weight

Men Very underweight Slightly underweight The right weight Slightly overweight Very overweight

Women Very underweight Slightly underweight The right weight Slightly overweight Very overweight

(n.27) 18.5 55.6 22.2

3.7 0.0

(n=38) 18.4 34.2 44.7

2.6 0.0

(n.385) I .o

13.8 54.5 30.4 0.3

(11472) 0.4 4.2

48.5 43.2

3.6

( n = 186) 0.5 0.5

13.4 72.9 13.4

(n=l7 1) 0.6 0.0 5.3

70.2 24.0

( n =29) 3.4 0.0 0.0

34.5 62.1

(n=55) 0.0 0.0 1.8

34.5 63.6

TABLE 3:

Cross-tabulation of desired weight by present weight (results expressed as percentages)

Present weight

Underweight Acceptable Overweight 0 bese weight

Desired weight Men Underweight Acceptable weight Overweight Obese

Women Underweight Acceptable weight Overweight Obese

( ~ 2 5 ) 44.0 56.0 0.0 0.0

(n.33) 51.5 48.5 0.0 0.0

(n=356) 0.0

98.9 0.8 0.3

(11.436) 5 .o

94.3 0.7 0.0

(n.181) 0.0

65.2 34.8 0.0

(n= I6 I ) 0.0

78.9 21.1 0.0

(n=29) 0.0

20.7 75.9 3.4

(n=52) 0.0

40.4 55.8 3.8

CRAWFORD & WORSLEY 64 C O M M U N I T Y H E A L T H S T U D I E S

Ideal weight

The respondents were asked what they believed their weight should be ideally. Using this ‘desired’ weight, a ‘Desired Body Mass Index’ was computed and the desired BMls were used to classify subjects as underweight, acceptable, overweight or obese according to Bray.? Cross-tabulations of present weight category (underweight, acceptable weight, et cetera) by desired weight category were performed separately for men and women (Tattle 3). These revealed several important findings: - Among the overweight, more women than men

wished to lose weight. For example, 79 per cent of overweight women wished to lose weight, compared to only 65 per cent of !:he men.

~ Among the obese, almost all wished to reduce weight. About 40 per cent of the c’bese women and 20 per cent of the obese men wished to reduce their weight to the acceptatile range; the remainder wished to lose lesser amounts to put them into the overweight category. Approximately five per cent of women in the acceptable weight range wanted to shed SO much weight that they would be classified as ‘underweight’ according to Bray’s scheme. The proportion of 18-30 year old women desiring underweight status was 12 per cent in the Melbourne sample, and 16 per cent in the Adelaide sample.

- This attraction for underweight status is further supported by the observation that only half of the underweight women wished to increase their present weight to the ‘acceptable’ level.

Demographic characteristics of th,ose who do not desire ‘acceptable’ weight status.

The two groups which do not see ‘acceptable’ weight status as ‘ideal’ are older overweight and obese men and women (mean ages: Adelaide men 53.0 years k 15.5; Melbourne men:47.5 years? 16.4; Adelaide women 59.3 years k 13.4; Melbourne women 53.7 years ? 13.5); and young women who wish to remain or become underweight (mean ages of the former: Adelaide: 31.5 years k 15.2; Melbourne: 22.6 years k 7.7; and of the latter: Adelaide: 27.2 years t 4.6; Melbourne: 26.1 years k 8.6).

Fewer of the overweight women of low occupational status wished to reduce their weight to the ‘acceptable’ range* (proportions wishing to reduce weight: Adelaide ~ high status 92 per cent, middle status 87 per cent, low status 59 per cent, 6 0 . 0 1 ; Melbourne ~ high status lC0 per cent, middle status 85 per cent, low status ti9 per cent,

* A chi-squared test of desired weight X occupational status was performed.

6 0 . 0 2 ) . N o other significant occupational status differences were observed in any other body mass groups.

Discussion

The results presented here give two major causes for concern. Along with the findings of the recent Risk Factor Prevalence surveys,’ * they indicate that there are many overweight and obese people in Australia. More disturbing however, is the finding that a large number of these people, mainly older persons, do not have any weight reduction goals in mind. This implies that obesity-reduction campaigns conducted in this country have not been altogether successful.

Results from a recent survey conducted for the Better Health Commission suggest that persons over 55 years see little point in improving their health habits.20 The same study also showed that people in this age group tend to rely heavily on doctors, nurses and other health professionals for health information. Future weight reduction campaigns therefore need to target the over-fifties more specifically and need to emphasize the feasibility and accompanying benefits of weight loss via general practitioners and allied professionals.

A second cause for concern is the apparent desire of many women to achieve or maintain underweight status. It is particularly disturbing that 12-16 per cent of women under 30 years wish to achieve or maintain a low Body Mass Index, which may be indicative of anorexia.21 According to a recent review the increasing prevalence of anorexia nervosa and similar eating disorders can be partly attributed to sociocultural pressures on women to diet in pursuit of a thinner shape. Garner postulates that dieting in young females may potentiate eating disorders in those who are psychologically vulnerable.22

Between one-third and one-half of ‘acceptable weight’ women in this study described themselves as at least slightly overweight. In Australia, as in other Western cultures, there are great pressures on young women to diet in order to achieve slimness.23 This is reflected in the type of nutrition information published by the press. Conner Reilly’s study of newspaper articles revealed that weight control was the nutrition topic most often written about, comprising 30 per cent of all items.24 Of the weight control articles reviewed, 44 per cent were concerned with obesity (paying particular attention to restoring a desirable body image), while 46 per cent dealt with dieting and special diets. Only 10 per cent of all weight control articles (3 per cent of all nutrition articles) dealt with anorexia and related eating disorders in detail.

C R A W F O R D & W O R S L E Y 65 C O M M U N I T Y H E A L T H STCIDIES

Clearly, more attention should be given to offsetting the unrealistic demands of fashion and the cult of 'feminine' thinness.13 Such demands may be strongest among women of high occupational status, as has been suggested by the present results. We need to understand more of.the social pressures on women to ensure that anti-obesity campaigns do not cause more harm than good.*' Kalucy has sounded a relevant warning to health professionals, noting that: 'The medical profession has contributed significantly to the prevailing weight conscious social climate. It may now have to consider more carefully the ramifications of certain aspects of preventive health programmes. Even the best intentions can sometimes have undesirable results'.26

In conclusion, it appears that a number of people

perceived their ideal weight as lying outside the 'acceptable' range. Generally, women were more likely to perceive themselves as overweight and to wish to weigh less. Many men and women regarded themselves as at least slightly overweight. It would have been worthwhile to have collected some information on why the subjects felt the way they did about their weight; unfortunately such data was not obtained. A more detailed study of weight control practices, beliefs and attitudes to dieting, weight control, body shape and weight is currently being conducted.

Acknowledgements The authors wish to thank Ms. H. Dornomand Ms. J . Gowland who assisted with the running of the study in Victoria and South Australia.

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CRAWFORD & WOKSLEY 61 COMML'NITY H E A L T H STUDIES