Very many people engage in dieting. Health professionals could be forgiven for assuming that reducing diets are for fat people. However, this is far from the case.
Up to one third of men and women in the western world is said to be overweight. Yet twice as many believe that they weigh more than they should. Thinking that one is overweight is more common in normal weight women than in men. Moreover, not only do these normal weight people believe they weigh too much, many also have lives that are in some way restricted by worry about weight.
In this context, dieting is extremely common and people of all weights are trying to lose weight. In 1980 – 81 Dr. Jeffrey and his colleagues from the University of Minnesota surveyed 2000 people living in the town of Minneapolis. According to the people they questioned, 72% of the women dieters and 44% of the men had never been overweight. This finding has been replicated in many other studies, namely that many people, women in particular, mistakenly believe themselves to be overweight and at least one in every two women who are NOT overweight has tried dieting.
The popularity of dieting is fuelled by several factors, the first being a national aversion to fatness. This attitude sets in at a very young age. School children in one study showed a stronger aversion to being overweight than to being blind or physically crippled. Even children as young as 8 are restricting their food intake and by age 15 one in three has been on a diet.
The second factor is a multi million pound slimming industry which grows ever more inventive in its attempts to persuade veteran dieters that “this one really works”. This industry also creates the popular myth that body fat is a “Cinderella substance” which fits on top of the real person underneath, that can be controlled with the right diet and the right degree of willpower.
Hence, as far as dieting success is concerned, much of what is written in the popular press has an optimistic flavour. Despite poor success rates, even the professionals who proffer diet plans believe that successful dieting is possible – any one can do it if they try hard enough to follow the advice they are given. In actual fact there is no evidence for this assumption. At best modern weight control programmes can achieve weight losses of around 15 pounds but the proportion of people who maintain their losses for over 5 years is in single figures. Only one in twenty people who join commercial weight control programmes is said to reach goal weight – but not all of these people are clinically obese and there is no information about how many of the successes re-enrol at a later date. Further, half of all dieters put back even more weight than they have lost. Obviously something else is going on.
Dieters and non diets alike explain the difficulty of losing weight in terms of a concept called “willpower” – successful dieters have it and failed dieters do not. This idea is so popular as an explanation for failure to lose weight that advisors who prescribe weight loss plans for people are puzzled, angry or at least resigned when a person returns to be weighed not having lost an ounce and often having gained weight.
Researchers have battled long and hard with the question of what distinguishes the successful from the unsuccessful dieter.
At first they explained differences in success / failure in terms of personality, neuroticism and many other psychological constructs. Now we know that the difference between success and failure cannot be explained by one single phenomenon.
At the very least, there are some facts about the experience of dieting and its psychology which women with anorexia, bulimia, binge eating or obesity should understand, if they wish to overcome their eating problem or lose weight successfully. This will explain why dieting is so difficult and why when weight is lost most people cannot keep it down.
The physical risks of dieting
The first of these has something to do with the physiological changes we produce when we eat less than we need. There is increasing evidence that dieters get locked into a losing battle with their own bodies which fight like mad to resist the starvation process. Many dieters are depressed by the decreasing weight losses which occur after the initial phase of dieting so it is useful to explain clearly the reasons for this. Such an explanation would go something like this.
“When we diet you exchange automatic internal regulators of appetite for conscious mental ones. You teach yourself to stop responding to hunger cues, both the lets eat and the lets stop messages. So when people break their diets either temporarily or for good they run the risk of rebound binge eating.
Also, as we diet our body shuts down, adjusts to surviving on less energy and our metabolic rate, the rate at which we use up energy – goes down. The more weight we lose the less food we need, and at a lower weight we may have to continue eating at least a bit less than we did when we were heavier. Also significant weight loss leads to lethargy which slows down the metabolic rate still further. So at the end of a diet we cannot necessarily go back to eating as much as we did before. We can unwittingly make the situation even worse by losing weight too fast. If we lose at a rate of a pound or two a week we are likely to lose mostly fat, but if we lose weight faster we are likely to lose lean tissue or muscle as well as fat. This is important because our metabolic rate is determined by the amount of lean tissue we have; the less we have the lower our metabolic rate goes and the less we need to eat. So the optimum way to lose weight is slowly.
In addition there is growing evidence that repeated cycles of dieting can make matters even worse, in that people may have to eat less and for longer to lose the same amount of weight. Kelly Brownell has reported on research done by colleagues on the effects of weight cycling in rats, which is like yo yo dieting in humans. A group of rats were dieted and then re-fed. In the second cycle of restriction the rats needed 46 days on the same calorie intake to lose the weight they had previously lost in 21 days. It rook them only 14 days on the second occasion to regain as much weight as they had regained previously in 46 days. While we cannot extrapolate from humans to rats and no firm conclusions can be drawn from such human studies as exist it is interesting to note that athletes who have to keep within a weight range from one season to the other complain that it becomes progressively harder to lose the same amount of weight from one season to another.
Hence no diet should be embarked on by anyone of any weight without considerable planning.
Dieters in several studies have been described as experiencing a changed relationship with food, such as powerful urges to eat or excessive preoccupation with food and feelings of being out of control around food, hence they are naturally vulnerable to breaking their diet in the face of temptation.
The emotional effects of dieting
The psychological as well as physiological effects of drastically reducing food intake have been well documented by Ancel Keys in a series of much quoted experiments conducted on young healthy male conscientious objectors without a history of weight problems. They participated in these experiments as an alternative to military duties during the Korean war. The men ate normally during the first three months of the experiment while their eating patterns and personalities were studied. They were then put on strict diets where their normal food intake was halved for a period of three months. Afterward they went through a three month rehabilitation period where they were reintroduced to eating normal amounts of food.
What happened suggests that the effects of dieting are far reaching. Food became the main topic of conversation, reading and daydreams for almost all of the men. Men who previously had no particular interest in food and cooking became fascinated by cookery and menus. About half way through the semi starvation period 13 of the men expressed an interest in taking up cooking as a career after the experiment was over. Many of the men found it impossible to stick to the diet – they ate secretly on impulse and felt guilty afterwards.
Psychologically they became more anxious and prone to feeling depressed, they had difficulty concentrating and they began to withdraw from other people and became less sociable. Two of the men had emotional breakdowns and one cut off the end of his finger apparently hoping that he would be excused from the study. The remainder developed a “buddy” system to help them stop cheating.
The terrible internal conflicts which are the result of food restraint are a source of continual stress, according to psychologist Jane Warble. All dieters score higher than non dieters on measures of emotional agitation and are more likely to show impaired mental performance.
Dieting also changes the way we feel about our body. In the Keys experiment it was noted that men who had no previous concerns with their appearance and weight began to experience changes in the way they perceived their bodies, paradoxically several of the men complained about feeling overweight even though they had lost weight and they began to experience critical evaluations of their body shape and size.
At the end of the dieting period the men’s personalities reverted to normal. However, many of them continued to have problems with eating. Even though they were allowed to eat as they wanted many of them found that they could not stop eating when they were full and generally ate more than they thought they wanted or was good for them. They continued to be preoccupied with food and some reported that their cravings were even worse than before. Many had cravings for specific foods such as sweets, dairy products and nuts. Many of them snacked between meals even if they had not done so before. Another four weeks later ten of the 15 men who were still in touch with the researchers became so anxious about their weight that they put themselves on another diet and a few were continuing to eat prodigious quantities. Three months after the experiment food was still a major concern for 15 out of the 24 men and this continued for a further 8 months after the diet was over.
Psychologists called Herman and Polivy at the University of Toronto have underlined the effect of food restriction on willpower in an experiment on dieting and non dieting students who were invited to eat as much ice cream as they liked after being given three different “pre loads” – one glass of milk shake, two milk shakes or nothing at all.
While the non-dieters behaved as expected, eating less ice cream after one milk shake than none, and even less ice cream after two, the dieters actually ate most ice cream after the biggest “pre load”.
According to the psychologist the effect of the milk shake was to undermine the dieters resolve, temporarily releasing them from their vows of abstinence. After the milk shake, instead of doing penance for the calorific sin, the dieter persists in sinful indulgence, say the psychologists. After all, if staying on the diet is no longer possible then why not make the most of the situation. This seductive thought process – I may as well be hanged for a sheep as a lamb – is a trap which awaits all dieters. After succumbing to one biscuit you feel such a failure you consume the whole packet. You decide to ditch the diet for the day and start again tomorrow.
But as Herman and Polivy point out, in anticipation of deprivation to come, dieters indulgences “ the night before” can reach legendary proportions. The seeming inability of diets to stop once they have started stem from the Faustian bargain they made with themselves at the start. Included in the loss of normal internal controls are the normal processes involving satiety. Dieters do not eat interminably once their rules are broken but they eat far more than non dieters do.
By denying themselves food, dieters also make it much more important. Dieters are more likely than non-dieters to turn to food when they are emotionally anxious or depressed. This phenomenon is created by dieting itself. At a recent study carried out in London, female volunteers were divided into three groups, the first went on a strict diet, the second a rigorous exercise programme and the third neither dieted nor exercised.
After 5 weeks the subjects took part in an experiment which assessed their food intake while watching a stressful film. Bowls of sweets and nuts were left beside them and they were told to eat as they liked. Women in the diet group ate far more than the others.
So it seems the effects of reducing food intake for a period of time are powerful, and what makes these experiments interesting is that the first described the experience of men who are not unduly concerned about food and weight. They experienced feelings and thoughts which are not unlike those experienced by people with anorexia – with their concerns about hoarding food and seeing themselves to be fatter than they were. What is more, the experience of dieting in itself – irrespective of personality and background engendered in the men in the Keys experiment, a concern about food and weight which they had not experienced previously. It is not unfair to assume that dieting will create these effects in all who try it out.
Aside from the psychological and physiological effects of dieting, when we consider advising people to diet we must bear in mind what we know about they way human beings respond to and comply with any kind of advice, medical and otherwise. Compliance will always be affected by the process itself whether it is simple or complex, the degree of behavioural change needed and whether it fits with the personality and lifestyle of the person. Compliance will be affected by the value of the outcome, and the goals of dieting – weight loss – may contain unrecognised difficulties if achieved. Compliance is also affected by many factors in the dieter herself, including beliefs about his or her personal efficacy, ability to handle lapses, singularity of purpose and ability to muster the right kind of social support. Kelly Brownell has also identified a crucial element influencing the prognosis of dieting behaviour which he defines as “emotional readiness.” This concept proposes that in order for dieting to be successful one has to go into “training” for it in much the same way as one would go into training for other projects like climbing a mountain or studying for an exam.
Health risks of dieting
It is an article of faith among doctors that obesity is a health risk contributing to deaths from circulatory disease, cancer and respiratory disease, and also increases the risk of diabetes, high blood pressure, infertility pregnancy complications, gall bladder disease and liver problems.
Yet there is also strong evidence that yo yo dieting presents a considerable risk to health, more in some respects than the obesity is designed to conquer.
In a large scale US study reported last year in the New England Journal of Medicine, men and women whose weight fluctuated often or greatly over a period of many years were found to have significantly higher risk of death – particularly from heart disease – than those with relatively stable – even if high – weights. We must ask therefore if it is the dieting associated with obesity rather than the obesity itself which contributes to the risk of ill health.
But even if you accept that fat is a health risk it is important to distinguish between moderate and mild overweight. Being slightly underweight is a greater risk than being slightly overweight.
Undisputed as a health risk of dieting are the eating disorders particularly anorexia and bulimia which can at their most extreme be life threatening. Although not all dieters develop eating disorders, these disorders are invariably preceded by diets.
The set point theory
As we have already noted, the agenda underlying most diet plans is that people can move toward a target weight, defined by their height and build, move toward it gradually (or quickly with additional assistance such as slimming pills or meal plans) and maintain it once it has been achieved, usually on the assumption that pleasure with ones new size will be sufficient to motivate one never to overindulge again. But as we have seen, this process is not easy since the body makes strenuous efforts to resist externally planned changes.
Many scientists believe that people are genetically programmed to maintain their weight within a set-point range which varies from person to person regardless of other similarities like height.
This offers the best explanation for the body’s resistance to weight reduction. Set point theory proposes that being overweight and underweight should be understood in terms of being above or below an individual’s set-point. A very thin woman may appear underweight but may be appropriate for her body, actually being at or above her set point.
Although set point theory is not universally accepted, it is a fact that overweight people defend their fat stores as rigorously as those of normal weight. Also medical science has come up with evidence of a set point mechanism (see my notes on the hypothalamus) and leptin studies.
Other studies in the set point theory suggest that it is influenced by diet and lifestyle, cigarette smoking and levels of exercise. For example regular aerobic exercise promotes a lower set point as long as you keep it up, while diets high in fat and sugar seem to promote a higher set point. And dieting seems to promote a higher set point.
Set points also tend to increase with age which is why it is unrealistic and probably unhealthy to aim to maintain your teenage weight in your 30s and 40s. Because of the influence of the media many people who are preoccupied with dieting have chosen a target weight outside their set point weight range which they are unlikely to maintain, and then only through a great deal of suffering.
Although the flavour of this essay in relation to dieting is rather negative, it would be imprudent to suggest that all dieters struggling with the cravings and emotional consequences of dieting, should forthwith reject their diets. Many of these people have become locked in a faulty relationship with food, and many are out of touch with their normal appetite, only able to maintain some semblance of control within the guidelines of any diet plan. They stand in danger of gaining weight quickly if they are not given advice to help them over what may be a lengthy transitional period.
Alternatively, well meaning magazine articles suggest that chronic dieters should forgo dieting in exchange for “healthy eating” – the implied promise being that if you learn to eat normally again you will lose weight. This is not guaranteed, even so, such a strategy is not likely to work immediately. Dieting still has credo, and the enormous publicity given to programmes like the Dukan diet makes its appeal globally irresistable. Experts must work hard to help a person let go of the emotional fix they get when they engage in dieting and when they replace it with moderate eating – which is invariably less exciting.
Giving up dieting requires complex interventions, based on education, re-evaluating the values and attitudes which create body insecurity in women, reality testing, re-framing food, and helping each individual find a formula for eating which is compatible with their lifestyle and physiology. This is our challenge in a society that still places enormous value on food restraint and self control.