The Metabolic Effects of Eating Less

Dieting affects your metabolic rate. If you start to eat less your body slows down the rate at which it functions.

It is only relatively recently that there have been ampleamounts of food available to most people in the western world. In terms of human existence on earth we are still programmed to deal with droughts, food shortages and periods of starvation. It is far more damaging and more likely in evolutionary terms for the body to starve to death than it is to overeat. And so we have evolved with the perfect method for avoiding starvation during a period of food shortage: storing excess food when it is available. This excess food is stored mainly in the form of fat, which is oxidised to produce energy when needed.

Metabolic rate refers to the amount of energy made available for use for a specific period of time. Our metabolic rates are also perfectly adapted for food shortages. If we decrease our food intake our bodies prepare themselves for the anticipated assault on stored food. The metabolic rate decreases so that the body can function as efficiently as possible and therefore use as little energy as possible and as little stored fat. Dieting for a period of fourteen days can lead to a decline of up to 20 per cent of the metabolic rate.

A recent study at the Rockefeller University in New York examined the effects of dieting on dieters' daily energy requirements. A group of obese people were studied; they had lost substantial amounts of weight and yet were still overweight by an average of 86 pounds. They found that as they lost weight their daily energy requirements dropped accordingly. After they had lost an average of 124 pounds their calorie requirements had dropped by an average of 28 per cent to become lower than those of normal-weight people. As they lost weight their bodies were using any available food more efficiently.

Although irritating to the dieter who wishes to lose weight, it makes perfect sense to the body which is responding to an evolutionary history of dealing with the lack of food. Excess food is still only a relatively recent development, and the desire to be thin by rejecting food makes no sense to our sense of survival.

So, even if dieters are managing to eat less food than non- dieters and less than they would do if they were not dieting, dieting reduces their metabolic rate. Any food eaten is used more efficiently and the need for metabolising fat is minimalised. To lose weight and maintain this weight loss, dieters have to eat less consistently, and to compensate for a decreasing metabolic rate they have to eat less and less over time.

But what about the times when dieters are eating more than non-dieters and perhaps even eating more than they would do if they were not dieting at all?

Diet-Breaking

It is often assumed that diets do not work because the dieters are not actually dieting. The dieting industry tells us that failed dieters are weak-willed and are simply not sticking to their diet. The responsibility for not losing weight is placed firmly on the dieter's shoulders with no understanding of the processes which constitute diet-breaking.

Experimental work shows that dieters overeat both in the laboratory and in naturalistic studies. Perhaps this behaviour is an illustration of diet-breaking, suggesting that not sticking to a diet is a far more complex issue than simply a lack of determination.

So why do dieters not stick to their diets? Surely all they have to do is eat less food?

Anyone who has ever dieted can provide you with reams of reasons why they break their diets, and will cite hundreds of examples of times when they have eaten more than they intended. Dieters may recall the different causes for their episodes of 'over-indulgence' and yet most dieters still blame themselves, and regard themselves as failures.

I want to draw upon the results of an experiment that I carried out as part of my work for my PhD, which suggests that diet-breaking is not the fault of the dieter, it does not reflect personal inadequacy, but is an inevitable consequence of the structure of dieting. Overeating is part and parcel of attempting to diet and is a consequence of trying to eat less, a direct product of dieting.

I carried out a study in the final year of my PhD which examined the effects of dieting and attempted to find out why so many diets fail and why women break their diets. The overeating behaviour shown by dieters in the laboratory is also reported by dieters in their day-to-day lives. Many women report fluctuating between days when they manage to eat less and days when they completely overeat.

Imagine sticking to 1000 calories a day for three days and then being invited out to dinner on the fourth day. Tempted by all the food available and the fact it is a special occasion, many dieterssay that they would eat more at the dinner than if they hadn't been trying to diet on the previous days. It is like thinking 'Oh what the hell. If I'm going to break my diet I might as well make the most of it.' It is similar to trying to give up smoking or drinking.

A friend of mine used to smoke only after six in the evening. She would never think about a cigarette before this and certainly wouldn't think of smoking first thing in the morning. At New Year she decided to stop smoking. From the moment she decided to stop all she could think about was cigarettes, even in the morning. She woke up desperate to smoke and found that when she actually had one cigarette, for the first few days of smoking again, she smoked more than ever before. The overeating found in dieters is similar to this.

It was originally believed that overeating was followed by a period of dieting, that people dieted because they had a tendency to overeat, and needed to compensate for episodes of indulgence. Dieters are all sorts of people. Some have problems with food, but the vast majority of dieters simply see themselves as being larger than society tells them to be. There is no evidence to suggest that dieters become dieters because they have episodes of overeating.

It was then proposed that dieting caused overeating — a complete reversal of the original theory. Researchers suggested that the overeating shown by dieters in the laboratory and reported in their day-to-day lives was a direct consequence of attempting to eat less. This is similar to the analogy with smoking; trying to stop smoking causes a desire to smoke more and trying to stop eating causes overeating. The difference is that stopping smoking is good for you, stopping eating isn't!

This idea was called the causal analysis of eating behaviour and suggests that attempting not to eat, paradoxically, increases the probability of overeating, the specific behaviour dieters are attempting to avoid. It represented a new approach to the eating behaviour of dieters and is an interesting reappraisal of the situation.

A study by Wardle and Beales in 1988 showed that dieters tended to overeat and the authors concluded that the results 'supported the idea that dieting causes disturbances of food intake'.

So why does this happen? Why does dieting cause overeating?

It is possible that overeating is a direct product of changes which occur as a result of dieting. Dieting could cause changes which increase the tendency to eat more.

It has been predicted from the causal analysis of dieting and overeating that increasing dieting would cause an increase in those factors related to overeating. Research suggests that changes in mood, state of mind, control and hunger occur as a consequence of dieting and could cause an increase in eating.

A classic study was carried out in 1950 by an American professor called Ancel Keys and his colleagues. Their aim was to evaluate the effects of a period of restricting calories, and to see whether reducing food intake caused overeating. Over a period of twelve weeks, thirty-six healthy non-dieting men received a carefully controlled daily food intake of approximately half their normal intake and consequently lost 25 per cent of their original body weight. Ancel Keys states that they developed a preoccupation with food, often resulting in their hoarding or stealing it. They showed an inability to concentrate, with mood changes such as depression and apathy being common. At the end of the period of dieting the men were allowed to eat freely and often ate continuously. They reported loss of control over their eating behaviour, sometimes resulting in binge eating. The author concluded that these psychological effects were not a function of the actual process of starvation, but were more likely to be due to the restriction of their diet.

In 1988, Warren and Cooper, in a study in Cambridge assessing the effects of dieting on both mood and the control of eating, placed seven men and seven women on a calorie- restricted diet for two weeks, and monitored any daily changes. They found an increase in feelings of loss of control, over eating and increased preoccupation with food.

Dieting seems to cause overeating by changing factors which contribute to eating more. The study which I carried out attempted to assess what these factors could be.

Up to 90 per cent of the female population diet at some time in their lives. The aim of the study was to examine the effects of these constant attempts at losing weight and to analyse their contribution to overeating. The failure to lose weight is often regarded as a sign of weakness and an indication that the dieter is not dieting properly. The following results suggest that failed dieters are simply responding to changes which occur during a diet and that breaking your diet is inevitable.

Effects of dieting on eating control

Dieting causes problems with the control of food intake. Attempting to diet results in increased calorie consumption in certain situations. Dieters feel more out of control than non- dieters, and experience chaotic eating patterns.

Dieters aim to eat less and to control their food intake. Women often attribute their perceived 'large size' to their inability to eat appropriately, believing that the reason why they are over their desired weight is because they overeat. Women look at other people's eating behaviour and believe that they eat less and at different times and understand their own behaviour in terms of loss of control. Dieting is regarded as a means to impose self- control and an external structure on their food intake. However, there is no evidence to suggest that, before dieting, women who are over their desired weight eat any differently or experience more episodes of loss of control than women who are at their desired weight. There is no evidence to suggest that larger women are more out of control than their thinner counterparts, or that women who decide to diet have experienced more overeating than those who don't.

However, there is evidence to suggest that dieting increases episodes of both perceived and actual loss of control. Imposing the dieting structure on food intake appears to have the opposite to the desired effect.

Perceived loss of control

Because of the limitations set by the diet, any food which is eaten beyond these limits is regarded as overeating and attributed to loss of control. Eating which would usually be seen as a large meal, a special occasion or a treat is regarded as overeating and indicative of lost control. The urge to eat which would usually be regarded as hunger is registered in terms of craving, and giving in to this urge is regarded as a weakness.

One woman said: 'When I start to diet I want to eat things I shouldn't eat. I want to buy fattening foods when I know I am on a diet.' She did not eat any more than before she began to diet; however, desires to eat certain foods are perceived as being a problem.

Actual loss of control

One of the main effects of dieting is that it contributes to actual loss of control over eating. Dieting causes increases in the preoccupation with food, making food more attractive, it alters responses to food, resulting in certain foods becoming 'forbidden', which triggers specific states of mind, and it causes mood changes. All these contribute to actual loss of control and result in the dieter eating more than she would have if she hadn't dieted in the first place.

One woman said that she found the diet very difficult. 'I feel depressed about dieting. I overate to start off with, felt depressed and then ate more. I felt that eating would make me happier, but I just felt guilty and wanted more to eat.' Dieting resulted in her eating more than if she had not tried to diet in the first place.

Another woman said: 'I can't cope at the moment with the feelings of deprivation that I get when I go on a diet. It wells up inside me and I panic and eat.' The diet made her feel deprived, and so even though she wasn't eating less, she then ate more to compensate.

Dieting aims to control food intake and to reduce food consumption. It aims to impose a structure on the dieter's behaviour and to result in weight loss. It doesn't appear to achieve either of these aims. The cognitive and emotional changes which occur as a response to dieting undermine attempts at eating less, and cause overeating, the very behaviour dieters are trying to avoid.

Dieting — The Vicious Circle

So what are the consequences of all this failed dieting? How do dieters respond to diet-breaking?

Dieting becomes a vicious circle, a merry-go-round which is difficult to get off. And each time around the effects are more powerful, more destructive and the weight loss less.

Effects of long-term dieting

If dieters are not really losing weight, what are they actually doing? It seems that all dieters have one thing in common: they are thinking about dieting. They are thinking about eating less and thinking about losing weight, but not necessarily achieving either of these aims. Sometimes dieters lose weight and sometimes they don't, but they are constantly trying to. Dieters share a common state of mind.

In the short term, dieting can provide a structure, a means of encouragement and support and a way to change your life. In the long term, failed dieting results in depression, a preoccupation with weight and food and episodes of overeating.

A recently documented effect of dieting is a process called weight cycling. This applies to those women who sometimes manage to lose weight but find that they put it back on again.

Have you ever dieted, lost weight and put back on more weight?

Have you ever dieted, lost weight, put it back on and next time around found it more difficult to lose?

Researchers at the University of Pennsylvania are involved in a weight cycling project to test the effects of 'yo-yo' dieting. Because so many dieters have reported that losing weight becomes progressively more difficult after putting weight back on, they first studied this effect in rats.

Researchers overfed a group of twenty-one rats to make them put on weight. They then changed their diet to make them lose this weight. They repeated this several times so that the rats went through a series of weight loss and weight regain. The first time around the rats took twenty-one days of dieting to reach their normal weight and forty-five days to regain the lost weight. The second time around the rats took forty-six days to lose the same amount of weight, eating the same amount of food, and only

fourteen days to regain the weight. Prolonged dieting meant that weight became easier to regain and more difficult to lose.

A similar study was carried out at Harvard Medical School and it was found that the pattern was similar for dieting women. It seems that repeated weight loss causes the body to use up stored fat more efficiently, and to live off less food. Repeated dieting and weight regain put the body into 'starvation mode', the metabolic rate decreases, and even when the weight has been regained the body still expects further deprivation.

Further research suggests that 'yo-yo dieting' has even more disturbing consequences. Yo-yo dieters seem to lose their pounds as muscle and regain them as fat. Thus prolonged attempts at dieting increase the body's overall fat content. A study of 1170 men in Pennsylvania found that over a period of twenty-five years those who showed the greatest weight fluctuations had the highest risk of heart disease.

In the short term dieting may make you feel good. In the long term it can result in far more problems than it solves. If you don't lose any weight you will feel a failure, dieting will become a habit and a way of life, and you will experience all the psychological changes which seem to accompany attempts at losing weight. If you do manage to lose weight, unless you can keep it off for ever, further weight loss will be more difficult and the physical and psychological problems greater than the simple problem of seeing yourself as fatter than you would like to be.

Dieting causes overeating. Overeating causes weight gain. Weight gain causes dieting. In fact, dieting no longer seems to refer to eating less. What most people are doing when they 'diet' is a combination of eating less and eating more. They swing from times of restricting food to times of compensating for this restriction. Dieting means attempting to eat less, but not necessarily doing so. What all dieters have in common is a state of mind. They are thinking about eating less — that is all. Very few dieters actually manage to do this; most of them simply think about it. And this is why the dieting industry is so powerful. Dieters never finish dieting. Dieters never get to the stage when they can finish with the dieting industry. Because dieting means further dieting and therefore further use of the ever growing industry which supports it.

Why continue to diet?

The majority of dieters are not fat, they see themselves as being fat. The majority of dieters do not lose weight, they spend their lives thinking about losing weight. Sometimes they may eat less, but will then compensate by eating more. Sometimes they may lose weight, but will quickly regain it.

All very upsetting.

As a result....

It could be assumed that the average dieter who never lost weight would stop dieting.

It could be assumed that all the negative side effects of dieting would deter women from launching into their next attempt to lose weight.

It could be assumed that the time and energy required constantly to think about what/when/where you eat would make dieting an unacceptable occupation.

It could be assumed that most dieters would soon become disillusioned and that the dieting industry would go bankrupt.

These are all plausible assumptions but are not the reality. Year in year out women pursue their desire to be thinner. As one diet fails the next is started. Leaving a slimming club means rejoining a few months later. Feeling a failure_; being fed-up, becoming preoccupied with food and weight are no deterrent to the perpetual dieter. The drive to be thin outweighs any of the undesirable effects of dieting.

But is it just the power of thinness?

Women start to diet because they want to be thinner and because thinness is associated with a multitude of other desirable qualities. Being thin means success, it means control and it means attractiveness. However thin they may be to start with, being thinner is still the goal.

Yet, whether or not they achieve this goal, dieters continue to diet. Dieting takes on a life of its own.

Dieting as a Way of Life

For a large number of women dieting becomes a habit. It becomes a pastime and a way of life. Women discuss what food they have eaten today, what they ate yesterday and what they will eat tomorrow. Dieting provides a focus. 'Have you seen the latest copy of . . . . "did you read that slimmer of the year's story in.. . '. Women diet together, friends can compare notes and exchange ideas. They can go to slimming clubs together, and they can even vomit together.

Slimming clubs often take on the role of social clubs or sports clubs. They provide a place for people to get together, to chat and to make friends. All the members of a slimming club have a common interest and a common goal. The clubs also provide a place to get away from the pressures of family life.

In the western world, families are shrinking and the extended family is no longer so extended. It is easy to become isolated, especially for women at home with children. A slimming club provides the place to get away from the strains of home-life, make new friends and find support. Most members of clubs are women and maybe this reflects not only women's desire for weight loss but also their need for support and friendship from other women.

Women diet because they want to lose weight but they continue to diet because it becomes a way of life, a social activity and a habit.