In an attempt to explain obesity and the failure of diets, many studies have shown that restrained eating may be the cause of overeating and weight gain. The Restrained theory was developed by Herman and Mack (1975) as a way to explain both the causes and consequences associated with the restrictions of food intake. They suggested that attempting not to eat often increases the chances of the individual overeating. However it is found that people are also told that restraint is a solution to weightloss and excessive eating. This can often enough lead to failed diets leaving the individual feeling depressed about their inability to control their weight.
Although, Ogden (1994) suggested that obesity may not be caused by overeating, overeating may be a consequence of obesity if restraint is recommended as a treatment. She also suggests that if trying not to eat leads to overeating then how do anorexics manage to starve themselves? This then raises the question as to whether there are other contributing factors as to why obese individuals can not restrain their food intake and maintain a diet without eventually overeating. Research such as Kern et al; suggest that for some people, dieting will always be difficult due to a genetic predisposition of obesity.
Restrained eating is associated with lowered and depressed mood. In addition, depression is linked to low self-esteem. So the restrained eaters have increased motivation to eat. However, if they violate their dietary limit, they tend to attribute it to their own useless nature and their inability to stick to a diet. Laboratory studies have shown that restrained eaters often overeat after high calorie preloads. Reviews of controlled studies dieting in the real world similarly conclude that reducing calorie input through dieting is not an effective method of losing weight (Mann et al, 2007). In the long term, between one and two thirds of dieters end up regaining more weight than they lost in the diet. Finally repeated attempts of dieting (yo-yo dieting) can in the long term increase the risks of heart disease.
However, much of the experimental work is carried out under controlled conditions in the laboratory. This gives it high levels of reliability but low levels of ecological validity. Dieting in the real world may involve more complicated issues than those studied in the laboratory. Research into obesity has also shown that weight gain is often caused by excessive emotional eating. This is caused by an intense emotion such as depression or stress and can cause the individual to be drawn to food as a way of jolting themselves out of a temporary low state. However if that low state is constant over a long period of time, the individual may begin to create a bad habit of this constant loss of inhibition.
Researchers have argued that this disinhibitory behaviour enables the individual to mask their negative mood with the temporary heightened mood caused by overeating. For example Polivy and Herman in formed female Participants that they had either past or failed a cognitive test, the researchers then gave them as much food as they wanted, or as small. The results showed that those who had failed the tested opted for larger amounts of food than those who had passed the test. Schachter (1968) developed an emotionality theory of obesity which claimed that although many people eat for emotional reasons; this is particularly the case for people who are obese. However since the research generated contradictory results further research into whether obese people eat more than non-obese people for emotional reasons.
Hunger is associated with increased arousal, vigilance and irritability, while after a meal we feel calm and sleepy and have general pleasuring feelings. Studies have also shown that people who are depressed or stressed increase their carbohydrate (especially sugar) and fat content of their meals, Gibson (2006).