Does Dieting Work?
Summary
Dieting sounds sensible - it’s a way of looking after our health, right? We have all come to believe it and the government encourages us to watch our weight and our food intake and exercise and eat well.
However, diets don’t work in the long-term. 95% of people who lose weight on diets put that weight back on, and more, within five years. Diet clubs such as Weight Watchers and Slimming World position themselves as a ‘lifestyle’, advocating a ‘balanced diet’. But, they are a business – part of the weight loss industry that, according to Market Research News in 2010, is expected to be worth $586.3m in 2014 – and they need to make a profit. They rely on people failing on diets and returning again and again. If diets worked, you’d only need to do them once.
Dieting teaches us nothing about appetite, about what our body needs, about how to satisfy hunger, about what foods work for us. Not only that, it makes us miserable, negatively impacts our self-esteem, and sets us up for a life-time of yo-yo dieting, which is so harmful to our mental and physical health.
Listening to your hunger and feeding it with the foods that you really like and really paying attention to every mouthful while you are eating, gives the most reliable guide to stopping eating when you are full. This intuitive eating - eating the foods you enjoy only when you are hungry (and only those) and stopping when you are full - will rebalance your metabolism and make your body work efficiently.
We want to highlight the role of the diet industry in de-stabilising appetites and desires. We believe that troubled eating and the so-called ‘obesity epidemic’ are merely more visible extremes of a much bigger, everyday phenomena: that we are accepting fear and hatred of our own bodies as natural, that we are accepting ‘I am not good enough’ as a fact.
We need to get back in touch with our appetites, enjoy our bodies and ditch dieting.
Further reading
‘We’ve forgotten how to eat’ – Susie Orbach
“The turning of foods, once relished, into foods that are bad or off limits, the avoidance of particular foods, the disapproval towards oneself for hankering after goodies, would, if it were a response to any other daily biological calling, be regarded as deeply worrisome. But when it comes to mad schemes involving food, no-one bats an eyelid.”
‘Is this the death of the diet industry?’ – Sue Thomason
“The diet industry is the most successful failed business in the world”
‘Hungry for change’ – Susie Orbach
We're all guilty of it - rewarding children with ice cream when they finish their greens or offering sweets when they are hurt. But this sends a dangerously mixed message about food and eating.
The evidence
DIETING DOESN’T WORK
University of California researcher Traci Mann and her co-authors conducted the most comprehensive and rigorous analysis of diet studies, analysing 31 long-term studies.
"You can initially lose 5 to 10 percent of your weight on any number of diets, but then the weight comes back," said Traci Mann, UCLA associate professor of psychology and lead author of the study. "We found that the majority of people regained all the weight, plus more. Sustained weight loss was found only in a small minority of participants, while complete weight regain was found in the majority. Diets do not lead to sustained weight loss or health benefits for the majority of people."
One study of dieting obese patients followed them for varying lengths of time. Among those who were followed for fewer than two years, 23 percent gained back more weight than they had lost, while of those who were followed for at least two years, 83 percent gained back more weight than they had lost. One study found that 50 percent of dieters weighed more than 11 pounds over their starting weight five years after the diet.
EVIDENCE THAT DIETING CAUSES BINGE EATING
Risk factors for binge eating onset in adolescent girls: A 2-year prospective investigation.
- Because little is known about the predictors of binge eating (a risk factor for obesity), a set of putative risk factors for binge eating was investigated in a longitudinal study of adolescent girls. Results verified that binge eating predicted obesity onset. Elevated dieting, pressure to be thin, modelling of eating disturbances, appearance overvaluation, body dissatisfaction, depressive symptoms, emotional eating, body mass, and low self-esteem and social support predicted binge eating onset with 92% accuracy, Classification tree analysis revealed an interaction between appearance overvaluation, body mass, dieting, and depressive symptoms, suggesting qualitatively different pathways to binge eating and identifying subgroups at extreme risk for this outcome. Results support the assertion that these psychosocial and biological factors increase risk for binge eating. (PsycINFO Database Record (c) 2010 APA, all rights reserved)
Dieting and binging: A causal analysis.
- Discusses the association between binge eating and dieting and presents sequence data indicating that dieting usually precedes binge eating chronologically. The present authors propose that dieting causes binging by promoting the adoption of a cognitively regulated eating style, which is necessary if the physiological defence of body weight is to be overcome. The defence of body weight entails various metabolic adjustments that assist energy conservation, but the behavioural reaction of binge eating is best understood in cognitive, not physiological, terms. By supplanting physiological regulatory controls with cognitive controls, dieting makes the dieter vulnerable to disinhibition and consequent overeating. Implications for therapy and the societal consequences of regarding dieting as a solution to the problem of binging are discussed. (59 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)
EVIDENE THAT DIETERS EAT MORE THAN NON-DIETERS
Control and loss of control over eating: An experimental investigation.
- The present study provides experimental evidence for the restraint theory's proposition of a causal link between restraint and disturbances in food-intake control. Twenty-seven obese women were randomly assigned to a diet group (high restraint), an exercise group (low restraint), or a control group for a 7-week group treatment program. On Weeks 4 and 6, all subjects participated individually in two laboratory sessions designed to investigate the regulation of food intake. In Session 1, food intake and appetite for food were assessed before and after a preload. In Session 2, food intake was assessed under stressful conditions. The results showed that the dieters ate more than either of the other two groups in all conditions. The possible mechanisms linking conscious regulation of eating with disturbances in control are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)
EVIDENCE THAT DIETING CAUSES WEIGHT GAIN
- This study examined the prospective relations of naturalistic weight-reduction efforts to growth in relative weight and onset of obesity with data from a community study of female adolescents ( N = 692). Initial self-labelled dieting, appetite suppressant/laxative use, incidental exercise, vomiting for weight-control purposes, and binge eating predicted elevated growth in relative weight over the 4-year period. Dietary restraint, self-labelled dieting, exercise for weight-control purposes, and appetite suppressant/laxative use predicted an increased risk for obesity onset. Data imply that the weight-reduction efforts reported by adolescents are more likely to result in weight gain than in weight loss and suggest the need to educate youth on more effective weight-control strategies. (PsycINFO Database Record (c) 2010 APA, all rights reserved)
Weight-loss attempts and risk of major weight gain: a prospective study in Finnish adults.
Weight-loss attempts may be associated with subsequent major weight gain, even when several potential confounders are controlled for. Genetic and familial factors may contribute to this association.
EVIDENCE THAT DIETING IS THE MOST EFFICIENT MEASURE TO PREDICT WEIGHT GAIN
Multiple types of dieting predict weight gain
This study examined measures of restrained eating, disinhibition, and emotional eating as predictors of weight gain during the freshman year. Using Lowe's multi-factorial model of dieting, it also examined three different types of dieting as predictors of weight gain. Sixty-nine females were assessed at three points during the school year. Weight gain during the freshman year averaged 2.1 kg. None of the traditional self-report measures of restraint, disinhibition, or emotional eating were predictive of weight gain. However, both a history of weight loss dieting and weight suppression (discrepancy between highest weight ever and current weight) predicted greater weight gain, and these effects appeared to be largely independent of one another. Individuals who said they were currently dieting to lose weight gained twice as much (5.0 kg) as former dieters (2.5 kg) and three times as much as never dieters (1.6 kg), but the import of this finding was unclear because there was only a small number of current dieters (N=7). Overall the results indicate that specific subtypes of dieting predicts weight gain during the freshman year better than more global measures of restraint or overeating.
EVIDENCE THAT DIETING INCREASES PSYCHOLOGICAL STRESS AND CORTISOL, TWO FACTORS KNOWN TO CAUSE WEIGHT GAIN
Low calorie dieting increases cortisol.
To test the hypothesis that dieting, or the restriction of caloric intake, is ineffective because it increases chronic psychological stress and cortisol production--two factors that are known to cause weight gain; and to examine the respective roles of the two main behaviours that comprise dieting--monitoring one's caloric intake and restricting one's caloric intake--on psychological and biological stress indicators.
Results: Restricting calories increased the total output of cortisol, and monitoring calories increased perceived stress.
Conclusion: Dieting may be deleterious to psychological well-being and biological functioning, and changes in clinical recommendations may be in order.
DIETING PARENTS (MOTHERS) INFLICT FOOD RESTRICTION ON THEIR CHILDREN
Five-year-old girls’ ideas about dieting are predicted by their mothers’ dieting
Depending on the question, from 34% to 65% of girls aged 5 years had ideas about dieting. Compared to girls whose mothers did not diet, girls whose mothers reported current or recent dieting were more than twice as likely to have ideas about dieting, suggesting that mothers’ dieting behaviour is a source of young girls’ ideas, concepts, and beliefs about dieting. Among mothers, more than 90% reported recent dieting, and most reported use of both health-promoting and health-compromising dieting behaviours.
Parent-child feeding strategies and their relationship to child eating and weight status
Parental feeding styles may promote overeating or overweight in children. A comprehensive literature review was undertaken to summarize the associations between parental feeding styles and child eating and weight status. Twenty-two studies were identified. We systematically coded study attributes and outcomes and tested for patterns of association. Nineteen studies (86%) reported at least one significant association between parental feeding style and child outcome, although study methodology and results varied considerably. Studies measuring parental feeding restriction, as opposed to general feeding control or another feeding domain, were more likely to report positive associations with child eating and weight status. Parental feeding restriction, but no other feeding domain, was associated with increased child eating and weight status.
Results: In both experiments, restricting access to a palatable food increased children’s behavioural response to that food. Experiment 2 showed that restricting access increased children’s subsequent selection and intake of that food within the restricted context.
Conclusions: Restricting access focuses children’s attention on restricted foods, while increasing their desire to obtain and consume those foods. Restricting children’s access to palatable foods is not an effective means of promoting moderate intake of palatable foods and may encourage the intake of foods that should be limited in the diet.
THE EVIDENCE FOR A SHIFT IN FOCUS FROM DIETING AND WEIGHT LOSS TO HEALTH AND NATURAL FOOD REGULATION
Weight science: evaluating the evidence for a paradigm shift.
Current guidelines recommend that "overweight" and "obese" individuals lose weight through engaging in lifestyle modification involving diet, exercise and other behaviour change. This approach reliably induces short term weight loss, but the majority of individuals are unable to maintain weight loss over the long term and do not achieve the putative benefits of improved morbidity and mortality. Concern has arisen that this weight focus is not only ineffective at producing thinner, healthier bodies, but may also have unintended consequences, contributing to food and body preoccupation, repeated cycles of weight loss and regain, distraction from other personal health goals and wider health determinants, reduced self-esteem, eating disorders, other health decrement, and weight stigmatization and discrimination. This concern has drawn increased attention to the ethical implications of recommending treatment that may be ineffective or damaging. A growing trans-disciplinary movement called Health at Every Size (HAES) challenges the value of promoting weight loss and dieting behaviour and argues for a shift in focus to weight-neutral outcomes. Randomized controlled clinical trials indicate that a HAES approach is associated with statistically and clinically relevant improvements in physiological measures (e.g., blood pressure, blood lipids), health behaviours (e.g., eating and activity habits, dietary quality), and psychosocial outcomes (such as self-esteem and body image), and that HAES achieves these health outcomes more successfully than weight loss treatment and without the contraindications associated with a weight focus. This paper evaluates the evidence and rationale that justifies shifting the health care paradigm from a conventional weight focus to HAES.
Size acceptance and intuitive eating improve health for obese, female chronic dieters.
The health at every size approach enabled participants to maintain long-term behaviour change; the diet approach did not. Encouraging size acceptance, reduction in dieting behaviour, and heightened awareness and response to body signals resulted in improved health risk indicators for obese women.
Current public health policy recommends weight loss for obese individuals, and encourages energy-restricted diets. Others advocate an alternative, 'non-diet' approach which emphasizes eating in response to physiological cues (eg hunger and satiety) and enhancing body acceptance.
Results: Over a 1 y period, a diet approach results in weight loss for those who complete the intervention (MOST DO NOT), while a non-diet approach does not (REMEMBER THAT THE MAJORITY OF DIETERS REGAIN THIS WEIGHT AND MORE). However, a non-diet approach can produce similar improvements in metabolic fitness, psychology and eating behaviour, while at the same time effectively minimizing the attrition common in diet programmes.