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Self-report dieting attempts and intentional weight loss in a general adult population : Associations with long-term weight gain and risk of type 2 diabetes

Year: 2020
Type: dissertation
Study design: Observational Study
Abstract: Obesity is a worldwide, major public health problem. It contributes to the risk of several noncommunicable diseases (NCDs), health conditions, and mortality; impairs functional capacity and the quality of life, and places substantial burden on health care systems and economies. Along with the obesity epidemic, dieting has become popular, and indeed successful weight loss has been demonstrated to decrease the risk of many NCDs. Weight loss, however, is difficult, and further, weight maintenance after weight loss appears to be nearly impossible for the majority of individuals. Accordingly, self-report dieting attempts and intentional weight loss (IWL) have been indicated to predict subsequent weight gain in the long term. Weight loss is not limited solely to individuals with obesity, but dieting is common among individuals within each weight category. Despite dieting being common at the population level, the research on its associations in general adult populations is scarce. The aims of this thesis were to study which factors (sociodemographic, lifestyle, metabolic, somatic health, and mental health) are associated with dieting; whether dieting modifies the association between quality of diet and obesity; whether dieting predicts long-term changes in body mass index (BMI) and waist circumference (WC), and the incidence of type 2 diabetes (T2D); and whether several background factors modify these associations. The study was based on data from the nationally representative Health 2000 Survey and on its follow-up, the Health 2011 Survey, 11 years later. The study sample consisted of participants aged 30 and older at baseline (n=8028). Of this sample, 6771 individuals participated in health examinations in 2000. Of the individuals invited to participate in Health 2000, 6319 were invited to participate in Health 2011. Of this sample, 4006 participated in health examinations in 2011. In Health 2000/2011, information on health, wellbeing and functional capacity was collected through health examinations (including measurements and blood samples), interviews and questionnaires. Information on dieting attempts (having tried to lose weight), IWL (having tried and having lost weight), and changes in weight during the previous year was collected via a questionnaire at baseline. A validated food frequency questionnaire (FFQ) was used to measure the habitual diet of the participants, and dietary data were used to form a modified Alternate Healthy Eating Index (mAHEI), representing quality of diet. Height, weight and WC were measured during the health examinations in both Health 2000 and Health 2011. Information on incident T2D during a 15-year follow-up was drawn from national health registers. The statistical analyses were based on linear and logistic regression models, and on Cox's proportional hazards model. In all, at baseline, 39% of women and 24% of men had attempted to diet and 15% of women and 10% of men had achieved IWL during the previous year. The dieters (BMI 29.1 [SD 4.97] kg/m2) were more obese than the non-dieters (BMI 25.7 [SD 4.17] kg/m2). Dieting attempts and IWL were associated with several sociodemographic, lifestyle, somatic health and psychological factors. Most of the factors had parallel associations among both sexes. However, dieting and BMI showed a stronger direct gradient in men than in women. Moreover, dieting was positively associated with having diabetes, hip or knee osteoarthritis, and short habitual sleep only among men. Dieting attempts modified the association between quality of diet and obesity; while among the non-dieters, no association emerged, among the dieters, higher quality of diet was indicatively associated with a higher likelihood of overweight or obesity. Dieting attempts, weight loss, and weight fluctuation during the previous year were associated with an increase in BMI and WC during an 11-year follow-up. The increase was greater among dieters with normal weight than among non-dieters with normal weight. Conversely in those with initial obesity, the increases among dieters and non-dieters did not differ. During a 15-year register follow-up, 417 individuals developed T2D. IWL during the previous year predicted an increased risk of T2D during the follow-up. The association was indicatively accentuated in men, younger individuals, individuals with a lower educational level, individuals with some unfavorable lifestyle habits (low quality diet, low physical activity, and short habitual sleep), and in individuals with low energy intake. The results suggest that at the population level, self-report dieting may be associated with greater subsequent weight gain and an increased risk of developing T2D in the long term. These findings may derive from dieting-activated biological mechanisms (e.g. lowered resting energy expenditure and increased appetite) that promote weight gain. Failed dieting may lead to repeated weight loss attempts and thus, to weight cycling. Alternatively, it is possible that dieters differ from non-dieters and are initially at an elevated risk of weight gain and of developing T2D due to other factors. The results that the risk of T2D is tentatively pronounced among those with IWL and some unfavorable lifestyle habits suggest that poorly conducted dieting in conjunction with unhealthy lifestyle habits in particular may be associated with disadvantageous consequences. In spite of these results, individuals with obesity and medical needs for weight loss should not avoid dieting. Dieting, however, should be conducted properly with evidence-based strategies and an emphasis on weight maintenance after weight loss. Among individuals with normal weight, on the other hand, unnecessary dieting attempts should be avoided and instead, focus should be targeted to learning healthy lifestyle habits in order to maintain normal weight and to prevent weight gain in the future.
Language: English
Field: Psychology
Open Access status: green
OpenAlex ID: W3050925908
Cites: 21
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Related to: 10