Does Dieting Work?

1.3.4.1 Maintenance of weight loss

A common charge levelled at dieting is that it is simply ineffective in controlling weight in the long term. Certainly there is a very high rate o f relapse amongst dieters who succeed in losing weight. Almost all those who successfully undergo weight reduction regain the weight lost within 5 years, although there is some suggestion that individuals who lose weight through commercial weight loss programmes and in the general population may be more successful at maintaining their lower weight than those from a clinical setting (Lowe et al 2001; Schachter 1982). The failure o f many overweight dieters to maintain a reduced weight represents a serious problem, since cycles of weight loss and regain have been associated with increased ill-health and psychological distress (Brownell and Rodin 1994; Gamer 1995). This has led some researchers to argue that acceptance of a stable but high body weight is preferable to attempts to reduce weight that might result in weight cycling (Gamer 1995). Nonetheless,

Chapter 1 : The case for and against weight control

the absence of any weight control in individuals prone to weight gain is likely to result not in a large but stable body size, but in a steady weight increase, since weight is strongly linked to age (Erens and Primatesta 1999). One study which examined the disease burden associated with a range of different patterns of weight gain, loss and maintenance throughout adult life reported that continuous weight gain was associated with the highest odds o f disease (French et al 1996). The negative health implications o f cycles o f weight loss and regain are by no means universally endorsed in the literature, and a large number o f studies have reported no links between health outcomes or psychological distresss and weight cycling (e.g. Simkin-Silverman et al 1998; Field et al 1999; Wing et al 1995). Williamson (1996) has suggested that much of the weight cycling literature has confounded intentional weight loss (e.g. dieting) with unintentional weight loss, which may be an indicator of pre-existing illness. Two reviews of the literature on the value of weight loss given the possibility of complications due to weight cycling (anonymous 1994; Jeffery 1996) have concluded that evidence of the damaging effects of weight cycling was not compelling enough to override the benefits of weight loss for obese individuals.

1.3.4.2 The weight status and weight change of dieters

Survey-type studies show that dieting is usually associated with higher, not lower weights in both adults and adolescents (as discussed above) and there is some evidence from cohort studies that adults and adolescents who diet generally show weight increases over the long term which are greater than those affecting non-dieters (French, Jeffery, Forster, McGovern, Kelder and Baxter 1994; Stice et al 1999). One o f the problems with naturalistic surveys o f this kind, however, is the fact that participants are not randomised into dieting and non-dieting groups. For many people dieting will be a response to weight gain, and it seems very probable that individuals who become dieters are more likely to be those with a predisposition for weight gain, so even though they gained more weight than non-dieters it is possible that they would have gained even more if they had not been dieting. This means that the effects of weight control on long-term weight gain are extremely difficult to judge using survey-type

Chapter 1 : The case for and against weight control

studies. Unfortunately very little research has examined the question of the efficacy o f specific dieting practices in a way sophisticated enough to sidestep these confounding factors, and none have focused on young people. One study which examined adults enrolled on a weight gain prevention program in the US suggests that although there were no links between global reports o f dieting and weight change over the four year period of the study, there was a dose-response relationship between the use o f some specific o f dieting practices (calorie reduction, increased consumption of fhiit and vegetables, reduced fat consumption, eliminating sweets and reduction o f the quantity o f food eaten) and cumulative reduction of weight gain over the four years (French et al 1999). Participants who reported engaging in these behaviours for longer durations reported lower levels of weight gains than those who followed them for shorter durations or not at all. This may suggest that the majority o f dieters do not apply dietary changes consistently enough and for long enough periods o f time to produce beneficial effects. A review of the literature on the efficacy o f dietary weight reduction practices (Brownell and Rodin 1994) concludes that long term moderate weight control behaviours may be beneficial in reducing age related weight gain. An important consideration in examining the possible benefits of dieting, then, involves the extent to which individuals successfully maintain suitable dietary changes over a protracted period of time.

This chapter has discussed a number o f research areas which contribute to the debate on the role of dieting as a health-risk or a health promoting activity, without closely examining the phenomenon of weight control and dieting as it is manifested in adolescents. The following chapter more closely examines the concepts of weight control and dieting, addressing the prevalence and patterning of attempts to control weight in young girls, and the range o f activities they adopt.