Ineffectiveness of Dieting

If the body weight were not closely regulated, it would be much easier to lose and gain weight. If weight loss were merely a reflection of total caloric intake, it would be a simple matter to lose weight by simply missing breakfast and eating normally the rest of the day. Theoretically, this should result in a 30- to 50- pound loss each year. With more drastic changes in eating patterns, we would expect to see even more dramatic weight changes. For instance, a change from 3000 calories to 1000 calories daily would theoretically reduce weight by 17 pounds the first month, and by over 200 pounds in a year.

Although the predicted weight gains or losses may occur over a short period of time with altered food intake, they are seldom seen for long periods of time. After the initial loss (which may be as much muscle and water as fat), the body weight tends to stabilize at some new lower level and no further change occurs.

Some researchers have theorized that this failure to lose weight reflects the decreased energy need in the body, which has been made smaller by the dieting process. Although our energy needs may fall a little, we should still be able to continue effective weight loss with a reduced calorie diet. Since we seldom see continuous weight loss at the predicted rate, there must be other influences involved. The major influence in preventing continued weight loss seems to be the WRM. Through its sensor systems, the WRM becomes “aware” that food intake is limited and that fat stores are becoming depleted. It “recognizes” this situation as dangerous, and directs changes in the body to conserve energy. The body can then function at a lower energy level, and weight loss stops or slows dramatically. The body is now much more efficient and can regain the lost fat with only a small increase in food intake. In addition, hunger is greatly increased, and the dieter becomes more and more driven by a powerful need to eat. This drive usually becomes so strong that few people can follow low calorie diets for long.

This mechanism explains the failure of traditional diets. Only about 25 percent of all dieters succeed in losing 20 pounds; and of those who need to lose more that 40 pounds, only 5 percent are able to do so.

An even more dramatic evidence of the WRM is the tendency of dieters to regain lost weight. More than 90 percent of them return to their previous weight within two years. It is interesting how often their weights are within a fraction of a pound of their previous weight. This in not only strong evidence of a regulating mechanism, but also evidence that it is sensitive to minor weight changes, and able to control the weight within a very narrow range.

Starvation Studies

Various animal and human volunteer starvation studies have shown evidence of a weight regulator, and insight into its actions. Animal studies (where food intake can be much more closely controlled) have shown that when a starving animal is again allowed to eat all it wants it will quickly gain back its previous weight. A growing rat who has been deprived of food will gain weight 20 times faster than its genetically identical litter mates when allowed to eat the same amount of food that they are eating, even though no extra food is given to compensate for the period of time that food was withheld. When they are provided all the food they want, the starved rats will eat more than their control littermates, and even more quickly gain weight to the expected level.

These studies provide clear evidence of a mechanism that closely controls weight by controlling energy balance and directing food intake. A notable human starvation study was done during Word War II with a group of conscientious objectors. They were placed on a starvation diet consisting of one-half of their usual food intake. As time passed and they became progressively more hungry, food became the most important thing in their lives. They began to dream about food and think about it most of the time. They even planned career changes to become bakers, waiters in restaurants, or work in other food-related fields. They became fatigued, lethargic and apathetic, and much less active. The WRM seemed to direct them to eat, but decreased their activity level to conserve energy.

When the forced starvation period was ended and they were allowed to return to normal eating, they never felt satisfied. Even after a big meal, they felt a desire to eat more. This feeling did not leave until their weight had returned to its normal level.  At this point, normal hunger drives returned and each subject returned to his normal eating and activity patterns.

Several observations related to this study suggest evidence of a WRM. The return to the previous stable weight is good evidence. The strong desire to eat even after eating a full meal suggests a driving mechanism designed to encourage enough eating to quickly regain the previous stable weight. The fatigue, apathy, and decreased activity during the starvation period suggest a mechanism designed to conserve energy and prevent further weight loss.

Liquid Formula Diets

Another interesting study was done wherein the total food intake for a group of volunteers was provided by a nutritious liquid obtained by sucking it from an unseen receptacle through a straw-like apparatus. Within a few days, subjects adjusted their intake to match their daily needs. When the caloric content of the liquid was doubled or halved (with no change in flavor or texture), the subjects would automatically decrease or increase their intake within a couple of days to supply the needed calories. At the end of the study, the weight of each subject had remained the same. This study again suggests evidence of an ability to measure and regulate food intake to maintain a constant body weight.

Force-feeding Studies

Several force-feeding studies have been performed on both animals and humans. Similar results have been observed. In some people, even huge amounts of extra eating will fail to cause weight gain. These people seem to have a weight-regulating mechanism that can vigorously defend the selected weight by wasting huge quantities of excess energy intake.

Most force-fed subjects will gain only a limited amount of weight and will then gain no more, despite a continued excess of food. This gain suggests a regulating mechanism that stimulates the wasting of extra energy to maintain the weight at some set level. These energy wasting processes are probably present in most of us, but may never have been fully developed. Since most Americans eat more than the minimum required to stabilize weight, we must all be regularly wasting some energy.

Another facet of the force-feeding studies that points to a WRM is that most of these subjects will quickly return to the pre-study weight even though no continuous effort is made to diet. The WRM will indefinitely prevent us from gaining weight, even on huge amounts of excess food, but seems more design to protect us from undereating or starvation.

Case Study with Increased Intake

A German scientist carefully measured his caloric intake for one full year and noted that he ate an average of 1760 calories per day. During the next year, he increased his caloric intake by 400 calories daily. At the end of the year, he was still very close to his original weight even though he had eaten enough extra energy to have gained over 40 pounds. He then increased his intake another 600 calories a day for another year without changing his original weight. Theoretically, he should have gained 60 pounds the second year, making a total of more than 100 pounds that he should have gained over the two-year period. This study is evidence of a WRM that can control the body weight within certain limits despite varying food intake.

Brain Surgery

Rat studies have been done where part of the hypothalamus was destroyed. If the particular area that controls the feeding drive (the feeding center) is surgically damaged, the animal will eat very little and will dramatically decrease weight. If the part of the brain controlling satiety or satisfaction (the satiety center) is destroyed, then the animal will eat more than usual and gain weight. He will then stabilize at the higher level and defend that weight. Both of these animal models will respond in the same way as normal rats to exercise and dietary factors that change the weight. If activity level increases, all three groups will lose weight, and if activity is decreased, all three groups will gain weight. These lesions seem to change the level at which the WRM is set. It still defends the body weight as before, but now defends a different weight level.

Brain Damage

There have been case reports where the part of the human brain that influences eating has been damaged through accident or disease. In some of these cases, a feeling of fullness or satiety is never reached and continuous hunger encourages excessive eating. In these cases, weight gain continues to a very high level, sometimes until death occurs. This is unlike the force-feeding studies where continued excess food intake only produced modest weight gain. In these brain damage cases, the WRM no longer functions to provide for energy wasting. A comparison between these brain damages, malfunctioning cases, and “normal” people gives a good evidence of a weight-regulating mechanism that directs appropriate food intake and energy balance.