The Psychology of Hunger

Eating and digestion supply the body with the necessary fuel needed for function and survival. Metabolism is the body's rate of energy (or calorie) utilization and several psychological mechanisms that keep our body in energy homeostasis by regulating the food consumption rate. For example, some psychological signals induce hunger and prompt the need to eat, while others stop the intake of food by producing satiety (the state in which we don't feel hunger anymore).

However, this is not the case as many people believe that hunger and eating simply occur when energy levels in our bodies run low and that we feel full when our immediate energy levels are restored. Our body monitors its energy supplies, but this information interacts with other factors; for example, the amount and variety of food to regulate the food intake—making hunger and satiety not necessarily linked to immediate energy requirements. Moreover, homeostatic mechanisms are designed to prevent us from running low on energy in the first place. In evolutionary terms, an organism that did not eat until its energy supply started to become low (in any absolute sense) would be at a serious survival disadvantage.

Finally, many researchers believe that there is a set point; or, as said biologically, a determined standard; around which body weight (or more accurately, fat mass) is regulated. This view holds that if we tend to overeat or undereat, homeostatic mechanisms alter our energy utilization and hunger to make us return to close to our original weight. But some researchers argue that the set point theory has limitations. They propose that as we overeat or undereat, homeostatic mechanisms make it harder to keep gaining or losing weight, but do not return us to our original weight. This makes us possibly settle in a new weight over time. Stated in a different point of view, "Biology does not determine a fixed body weight but rather, a range or zone of body weight."

Genes and Environment

Some individuals gain weight more easily than others even with less consumption of foods as well as  less fatty food consumption, while there are others who eat in excess with more fatty food and still stay slim for example: South Esat Asians who eat an excessive amount of fat still stay slim while others can gain weight with less amount of fat consumption. The reason for this can be in the genes, making some individuals more susceptible to gaining weight due to low metabolism, while others stay slim due to high metabolism. But there can be hormonal factors which contribute to weight gain and loss as well; such as thyroid conditions, thyroid dominance and menopause in some people. Heredity influences one's basal metabolic rate, causing a tendency to store energy as fat or lean tissue. Identical twins that are raised apart are about as similar body mass as identical twins who are raised together. This makes the genetic factors account for about 40% to 70% of the variation in BMI among both genders.

According to studies, over 200 genes have said to be have been identified as possible contributors to human obesity. However, although heredity affects our susceptibility to obesity, the environment does play a part in causing obesity too. There haven't been much changes in genes in recent decades, but the rate of obesity has had a significant increase. Experts believe the reasons to be the abundance of inexpensive foods that taste good but contain a high percentage of fats and carbs; a cultural emphasis on getting the best value, which contributes to the supersizing of menu items; and the advances in technology, which decrease the need for daily physical activity.

The Pima Indians of Arizona have provided a striking example of the way genes and environment interact in producing obesity. The Pimas have a genetic predisposition to obesity and diabetes, but before the 20th century, both these conditions were rare among the members of the tribe. Their native diet and the physically-active lifestyle prevented their genetic predisposition from expressing itself. But Pimas born after World War II, in particular, have had a dramatic increase rate in obesity with the adoption of a westernized diet and sedentary lifestyle. Today, the Pimas living in Arizona have one of the highest rates of obesity and diabetes in the world. In contrast to this, however, the Pimas living in northwest Mexico have a much lower obesity rate than their Arizona counterparts due to their sticking to a more traditional diet with more performance of physical labour.

Dieting and Weight Loss

However, for millions of overweight people, being fat primes them to stay fat, in part by altering their body chemistry and energy expenditure levels. This is an example of why obese people generally have high levels of insulin (a hormone that is secreted by the pancreas helping convert glucose into fat) than people with normal weight do. Substantial weight gain can also make it hard to exercise vigorously, and dieting slows the basal metabolism as the body responds to food deprivation with a decrease in energy expenditure.

Does this mean that diets are doomed to fail? The common adage of "Ninety-five percent of individuals who lose weight, regain the lost weight within a few years" evolved from a single study that was done decades ago. According to Albert Stunkard, one of the researchers, 100 obesity patients were given a diet and sent off, which was 'state-of-the-art' in 1959. There are no good longterm estimates of weight loss success rates in part because we rarely hear from people who succeed (or fail) on their own without the help from clinics or treatment programmes.

There are reports of around one-third of Americans trying to lose weight, although not all of them are the ones who necessarily need to lose weight. There are significant sex and ethnic differences in dieting emerging from adolescence. Some dieters are motivated by health consequences, while the primary motivators to be slim are psychological concerns and social pressures—especially among women. Which may begin as a diet may, unfortunately, evolve into a life-threatening eating disorder.

Psychological Aspects of Hunger

Eating is positively reinforced by the good taste of food and negatively reinforced by hunger reduction. We develop an expectation of eating being pleasurable, making it an important motivation to seek out and consume food. Even the mere thought of food can trigger a feeling of hunger.

Attitudes, habits, and psychological needs also regulate food intake. Have you felt stuffed during a meal yet finished it and gone on to have dessert as well? Beliefs such as not to leave food remaining on your plate, as well as condition habits of autopilot snacking while watching TV, may lead us to eat even when we are not hungry. Conversely, countless dieters tend to restrict their food intake even when hungry.

Social Pressure

Especially for women, such restrictions stem from social pressure to conform to cultural standards of beauty from Playboy centrefolds and beauty pageant contestants and fashion models. It is an indicator of a clear trend towards a thinner and increasingly unrealistic ideal female body shape starting from the 1950s. Given the deluge of "thin = attractive" mass media messages in many parts of the world, it's not surprising that a survey in Australia has revealed that, even though most young women there are of average, healthy weight, only a fifth are happy with it.

Among 12 to 19-year-old Chinese female students, 80 percent are concerned about their weight. Compared with male American high school students, female students are less likely to be overweight, but more likely to diet and think of themselves as overweight. In comparison to men, women became increasingly dissatisfied with their body image throughout the last half of the 20th century.

A study by April Fallon and Paul Rozzin suggests an additional reason for this. Female college students overestimated the needed body average to conform to male preferences, while men overestimated their necessary bulkiness to conform to women's preferences. Women also had the tendency to perceive their body shape as heavier than ideal.

A study in 2004, on American and Spanish men and women, replicated this study with men's overall perception serving to keep them satisfied with their figures, while women's perceptions placed pressure on them to lose weight. Whether it be Caucasian American, African American, or Hispanic American, the men seemed more likely to have ego-protective perceptions about their body shape than women do.

However, men, too, are influenced by cultural ideals. College men's satisfaction with their bodies tend to decrease when exposed to series of advertisements of muscular males, but not when advertisements of average-built men came on. College athletes with value for muscle function tend to believe that women's preference is for a more muscular body type than theirs, making them have a preference of being more muscular than they are. The general consensus is that women's typical need is to be thin, with men who are overweight wanting to be thin and thin men wanting to be more buff.

Environmental and Cultural Factors

Food availability is the most obvious environmental regulator of eating. For millions who live poverty-stricken or famine-ravaged regions, the scarcity of food limits consumption. In contrast, the abundance of high-fat foods in many countries is a contributing factor to a high rate of obesity.

The taste and varieties of food also regulate eating. Foods that taste good increase consumption, but during a meal and from meal-to-meal; we can grow tired of eating the same thing, causing termination of the meal more quickly. In contrast, food variety increases consumption as observed at buffets.

This is because, through classical conditioning, we learn to associate the smell and sight of food with taste; in return, these food cues cause hunger. You may not be hungry and feel no need to indulge yourself unnecessarily, but the sensuous aroma will change your mind, making you feel hungry when you are not, like when you get the smell of baked goods. Even rats who are already full and ignore available foods will eat again with classically conditioned lights and sound settings they are used to associate food with.

Many other environmental stimuli can affect food intake. For example, we tend to eat more when dining with others than when dining alone. Cultural norms influence when, how, and what we eat as well. In Mediterranean countries such as Greece and Spain, they often begin their dinner late evening (around 9 p.m.). By this time, most North Americans have finished their dinner. Also, although we love variety, we tend to be more comfortable with familiar foods, often feeling difficulty overcoming squeamish thoughts of unfamiliar dishes.

Obesity

The heaviest known male and female according to history records were both Americans, weighing 1,400 pounds and 1,200 pounds, respectively, according to the Guinness Book of World Records, in 2000. A few people had approached that weight, but according to the body mass index (BMI), which takes into account the height and weight of an individual; a staggering 25 to 30 percent of American adults are obese, with 30 to 35 percent being overweight. From Canada to the Palestinian west bank, the adult obesity rates recorded are 20 to 50 percent according to many studies.

Being Obese places a great risk on one's health, as well as targets of prejudice and stereotypes. Obesity is often blamed on lack of will-power, a dysfunctional coping mechanism, heightened sensitivity to external food cues, and emotional disturbances. However, researchers have no such consistent findings between obese and non-obese people. There are hormone-related conditions that can cause weight-gain without excess food consumption, too, and hypothyroidism is one of them. South-East Asians tend to stay slim even with high-fat food consumption due to their genes, which means genes may be in play in as well, in cases of obesity.