24.6 kg m"2 and 40% of the women had a BMI of >25 kg m~ . ... age, education and income on weight loss attempts was modified by the level of BMI. Women trying to ... becoming more important in all segments of the popula- ... Weight loss attempts are prevalent among both adoles- ..... b: Wilcoxon rank sum test or X -test.
Body mass index and weight change attempts among adult women The Norwegian Women and Cancer Study ANETTE HJARTAKER, PETTER LAAKE, EILIV LUND '
Keywords: body weight, health behaviour, population study, socioeconomic status, weight loss
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ones. 1 3 ' 1 6 ' 2 1 ' 2 3 ' 2 5 30 Another predictor is socioeconomic ccording to a recent report by the World Health 1 status which has shown a positive relation with weight Organisation, the prevalence of being overweight and loss attempts.15'-'1'-'2 Weight loss attempts may also be obesity is increasing worldwide, particularly in many 2 10 related to lifestyles, such as level of physical activity and Western populations. " Along with the increasing presmoking status. " ^ valence of being overweight and obesity there is a growing concern about leanness and fitness. Unfortunately, this Most of the material on weight loss attempts has been concern mainly seems to enlarge die discrepancy between generated in the USA. Some European reports have been actual and ideal body weight. The demand for leanness is published recently, 21 ' 34 but data concerning weight loss becoming more important in all segments of the populaattempts in adult European populations are still scarce. tion 11 and the number of persons considering themselves Given die widespread efforts to lose weight and ttieir as being overweight exceeds the actual number of overpotential impact on the public health problem of being weight individuals. 12 " 14 overweight and obesity, more information on the topic is warranted. Weight loss attempts are prevalent among both adolesIn this paper we examine the relationship between weight cents and adults and among both sexes, although conchange attempts and BMI, age, socioeconomic status, siderably more common among females. Prevalence reproductive factors, lifestyle and diet in a population-based estimates range from 33 to 48% for adult women and from study ofNorwegian women. Moreover, we examine whether 20 to 29% for adult men. 15 - 21 the impact of such factors may vary according to BMI. Not surprisingly, body mass index (BMI) is a powerful predictor of weight loss attempts. 21 " 25 However, the high prevalence of weight loss attempts, particularly METHODS among women, indicates that other factors may be Subjects important as well. One potential predictor could be age. This paper is based on data from a subsample of the Although die results are somewhat disparate, older people Norwegian Women and Cancer (NOWAC) study. The tend to be less likely to try to lose weight than younger subsample was drawn from the National Central Person Register February 1996 and consisted of 20,000 female * A. Hjartaker u , P Laake2. E. Lund' Norwegian citizens born 1927-1951. In July 1996 they 1 Institute of Community Medidne, University of Tromso, Norway received a mailed letter of invitation requesting informed 2 Section of Medical Statistics, University of Oslo, Norway Correspondence: Anette Hjartaker, MSc, University of Oslo, Institute consent and a self-instructive questionnaire. A written for Bask Medical Sciences, Section of Medical Statistics, TO Box 1122, reminder was sent to non-responders about 2 mondis after Blindern, N-0317 Oslo, Norway, tel. +47 22 851047, fax +47 22 851313, e-mail. anette.hJartakerObasalmed.ulo no the first invitation. Of those replying by 1 September
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Background: Based on concern about the widespread increase in being overweight and obesity along with a substantial demand for leanness, we wanted to estimate body mass index (BMI) and the prevalence of weight change attempts in a population-based sample of Norwegian women. Furthermore, we wanted to examine how weight loss attempts are related to BMI and to age, socioeconomic status, reproductive factors, lifestyle and diet Methods: A nationwide, cross-sectional study applying a mailed questionnaire was used. Out of a random sample of 20,000 women aged 45-69 years 10,249 women participated. Results: Based on self-reported data, the mean BMI was 24.6 kg m"2 and 40% of the women had a BMI of >25 kg m~ . More than 50% of the women were trying to lose weight and weight loss attempts were very strongly associated with BMI. Age, education, income, smoking status and perception of diet's importance to health were also significant predictors of weight loss attempts. The effect of age, education and income on weight loss attempts was modified by the level of BMI. Women trying to lose weight reported a different diet than those not trying to lose weight, irrespective of BMI. Conclusion: A large proportion of middle-aged women are trying to lose weight. BMI is predominant in explaining weight loss attempts. After adjusting for BMI, age, lifestyle and socioeconomic status also contribute to explaining weight loss attempts.
EUROPEAN JOURNAL OF PUBLIC HEALTH VOL 11 2001 NO. 2 1997, 10,249 women agreed to participate, giving a response rate of 51.2%. Corrected for non-completion (death, emigration, severe mental handicap or unknown address), the response rate was 51.4%. The response rate declined with age, ranging from 55.5% in the youngest age group (45-49 years) to 41.6% in the oldest age group (65—69 years) and women living in northern Norway were more likely to respond than women living in southern Norway (55.3 and 50.8% respectively). The study was approved by die Regional Committee for Medical Research Ethics and the Norwegian Data Protection Registrar.
Statistical analyses Statistical analyses and nutrient calculations were performed by means of the SAS software package, version 6.12 (SAS Institute, 1996). All reported p-values were two-sided and a significance criterion of p
