Weight loss, in the context of medicine, health or physical fitness, is a reduction of the total body mass, due to a mean loss of fluid, body fat or adipose tissue and/or lean mass, namely bone mineral deposits, muscle, tendon and other connective tissue. It can occur unintentionally due to an underlying disease or can arise from a conscious effort to improve an actual or perceived overweight or obese state.

Unintentional weight loss [edit]

Unintentional weight loss occurs in many diseases and conditions, including some very serious diseases such as cancer, AIDS, and a variety of other diseases.

Poor management of type 1 diabetes mellitus, also known as insulin-dependent diabetes mellitus (IDDM), leads to an excessive amount of glucose and an insufficient amount of insulin in the bloodstream. This triggers the release of triglycerides from adipose (fat) tissue and catabolism (breakdown) of amino acids in muscle tissue. This results in a loss of both fat and lean mass, leading to a significant reduction in total body weight. Untreated type 1 diabetes mellitus can produce weight loss. In addition to weight loss due to a reduction in fat and lean mass, fluid loss can be triggered by illnesses such as diabetes, certain medications, lack of fluid intake or other factors. Fluid loss in addition to reduction in fat and lean mass exacerbates the risk for cachexia.^[1]

Infections such as HIV may alter metabolism, leading to weight loss.^[2]

Hormonal disruptions, such as an overactive thyroid (hyperthyroidism), may also exhibit as weight loss.^[3]

One cutoff value of where unintentional weight loss is of significant concern is where there's a weight loss of more than 5% in the past month, or at least 10% during the last 6 months.^[4]

Causes of unintentional weight loss [edit]

• Starvation, a state of extreme hunger resulting from lack of essential nutrients over a prolonged period.
• Cancer, a very common and sometimes fatal cause of unexplained (idiopathic) weight loss. About one-third of unintentional weight loss cases are secondary to malignancy. Cancers to suspect in patients with unexplained weight loss include gastrointestinal, prostate, hepatobillary (hepatocellular carcinoma, pancreatic cancer), ovarian, hematologic or lung malignancies.
• AIDS can cause weight loss and should be suspected in high-risk individuals presenting with weight loss.
• Gastrointestinal disorders are another common cause of unexplained weight loss – in fact they are the most common non-cancerous cause of idiopathic weight loss. Possible gastrointestinal etiologies of unexplained weight loss are celiac disease, peptic ulcer, inflammatory bowel disease (crohns disease and ulcerative colitis), pancreatitis, gastritis, diarrhea and many other GI conditions can cause weight loss.
• Infection. Some infectious diseases can cause weight loss. These include fungal illness, endocarditis, many parasitic diseases, AIDS, and some other sub-acute or occult infections may cause weight loss.
• Renal disease. Patients who have uremia often have poor or absent appetite, emesis and nausea. This can cause weight loss.
• Cardiac disease. Cardiovascular disease, especially congestive heart failure, may cause unexplained weight loss.
• Pulmonary disease.
• Connective tissue disease
• Neurologic disease, including dementia^[5]
• In some people, certain medications may cause weight loss as a side effect.
• Stress can cause weight loss. However, recent research (Jastebott, Potenza et al. 2010) shows a correlation between obesity and high levels of stress.^[6]

Intentional weight loss [edit]

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Intentional weight loss refers to the loss of total body mass in an effort to improve fitness and health, and/or to change appearance.

Therapeutic weight loss, in individuals who are overweight or obese, can decrease the likelihood of developing diseases such as type 2 diabetes,^[7] heart disease,^[8] high blood pressure,^[8] osteoarthritis,^[9] and certain types of cancer.^[8] While being overweight had been thought^[8] to be linked to stroke there is no strong evidence to support that link.^[10]

Attention to diet in particular can be beneficial in reducing the impact of diabetes and other health risks on an overweight or obese individual.

Weight loss occurs when an individual is in a state of negative thermodynamic flux: when the body is expending more energy (i.e. in work and metabolism) than it is consuming (i.e. from food or other nutritional supplements), it will use stored reserves from fat or muscle, gradually leading to weight loss.^{[citation needed]}

It is not uncommon for some people who are at their ideal body weight to seek additional weight loss in order to improve athletic performance or meet required weight classification for participation in a sport. Others may be driven to lose weight to achieve a more attractive appearance. Being underweight is associated with health risks such as difficulty fighting off infection, osteoporosis, decreased muscle strength, trouble regulating body temperature and even increased risk of death.^[11]

There are many diet plans and recipes that can be helpful for weight loss. While some are classified as unhealthy and potentially harmful to general health, others are recommended by specialists. Diet plans are generally designed according to the recommended caloric intake, but the regimes that lead to most weight loss are those that promote physical activity.^{[citation needed]} Many dietary programs claim to be efficient in helping overweight individuals to lose weight with no effort. However, the long-term efficacy of these plans is questionable.^{[citation needed]}

Intentional weight loss is, in most cases, achieved with the help of diets, although weight loss is generally associated with some degree of change in lifestyle habits, or taking exercise.^{[citation needed]} Many dietary strategies have been designed to meet the needs of individuals seeking to lose excess weight. Calorie-restriction strategies are one of the most common dietary plans. Daily calorie requirements vary depending on a number of factors including, age, sex, and weight-loss goals. For instance, nutritionists suggest that at least 1,200 calories should be consumed daily by women to maintain health; men need 1,500.^[12] These recommendations apply primarily to healthy people who seek weight loss for a better body tonus. However, those whose obesity places them at increased risk for type 2 diabetes, heart disease, or other conditions, may require a more restricted diet. In some cases, obese individuals may need temporarily to restrict their daily calorie intake to 800 or even 500.^[12] According to the U.S. Food and Drug Administration (FDA), healthy individuals seeking to maintain their weight should consume 2,000 calories per day.^[13]

According to the Dietary Guidelines for Americans 2010 Executive Summary, released on 31 January 2011, those who achieve and manage a healthy weight do so most successfully by being careful to consume just enough calories to meet their needs, and being physically active.

Low-calorie regimen diets are also referred to as balanced percentage diets. Due to their minimal detrimental effects, these types of diets are most commonly recommended by nutritionists. In addition to restricting calorie intake, a balanced diet also regulates macronutrient consumption. From the total number of allotted daily calories, it is recommended that 55% should come from carbohydrates, 15% from protein, and 30% from fats with no more than 10% of total fat coming from saturated forms.^[14] For instance, a recommended 1,200 calorie diet would supply about 660 calories from carbohydrates, 180 from protein, and 360 from fat. Calorie restriction in this way has many long-term benefits. After reaching the desired body weight, the calories consumed per day may be increased gradually, without exceeding 2,000 net (i.e. derived by subtracting calories burned by physical activity from calories consumed). Combined with increased physical activity, long-term low-calorie diets are thought to be most effective long term, unlike crash diets which can achieve short term results, at best. Physical activity could greatly enhance the efficiency of a diet. The healthiest weight loss regimen, therefore, is one that consists of a balanced diet and moderate physical activity.^{[citation needed]}

Weight gain has been associated with excessive consumption of fats, sugars, carbohydrates in general, and alcohol.^{[citation needed]} Depression, stress or boredom may also contribute to weight increase,^{[citation needed]} and in these cases, individuals are advised to seek medical help. A 2010 study found that dieters who got a full night's sleep lost more than twice as much fat as sleep-deprived dieters.^[15][16]

The majority of dieters regain weight over the long term.^[17]

Therapeutic weight loss techniques [edit]

The least intrusive weight loss methods, and those most often recommended, are adjustments to eating patterns and increased physical activity, generally in the form of exercise. The World Health Organization recommended that people combine a reduction of processed foods high in saturated fats, sugar and salt^[18] and caloric content of the diet with an increase in physical activity.^[19]

An increase in fiber intake is also recommended for regulating bowel movements.

Other methods of weight loss include use of drugs and supplements that decrease appetite, block fat absorption, or reduce stomach volume.

Bariatric surgery may be indicated in cases of severe obesity. Two common bariatric surgical procedures are gastric bypass and gastric banding. Both are effective at limiting the intake of food energy by reducing the size of the stomach.

Dietary supplements, though widely used, are not considered a healthy option for weight loss.^[20] Even though a many are available, very few are effective long term.^[21]

Virtual gastric band uses hypnosis to make the brain think the stomach is smaller than it really is and hence lower the amount of food ingested. This brings as a consequence weight reduction. This method is complemented with psychological treatment for anxiety management and with hypnopedia. Research has been conducted into the use of hypnosis as a weight management alternative.^{[22][23][24][25]} In 1996 a study found that cognitive-behavioral therapy (CBT) was more effective for weight reduction if reinforced with hypnosis.^[23]

Crash dieting [edit]

A crash diet refers to willful nutritional restriction (except water) for more than 12 waking hours. The desired result is to have the body burn fat for energy with the goal of losing a significant amount of weight in a short time. There is a possibility of muscle loss, depending on the approach used.^{[clarification needed]} Crash dieting can be dangerous to health and this method of weight loss is not recommended by medical doctors.^[26]

According to the Academy of Nutrition and Dietetics,^[27] “If the diet or product sounds too good to be true, it probably is. There are no foods or pills that magically burn fat. No super foods will alter your genetic code. No products will miraculously melt fat while you watch TV or sleep. Some ingredients in supplements and herbal products can be dangerous and even deadly for some people” (2011). To feel healthier and live longer, the focus needs to be on making lifestyle changes to how a person eats.

Weight loss industry [edit]

The examples and perspective in this section deal primarily with USA and do not represent a worldwide view of the subject. Please improve this article or discuss the issue on the talk page. (December 2010)

There is a substantial market for products which promise to make weight loss easier, quicker, cheaper, more reliable, or less painful. These include books, DVDs, CDs, cremes, lotions, pills, rings and earrings, body wraps, body belts and other materials, fitness centers, personal coaches, weight loss groups, and food products and supplements.^[28]

In 2008 between US$33 billion and $55 billion was spent annually in the US on weight-loss products and services, including medical procedures and pharmaceuticals, with weight-loss centers taking between 6 and 12 percent of total annual expenditure. Over $1.6 billion a year was spent on weight-loss supplements. About 70 percent of Americans' dieting attempts are of a self-help nature. Although often short-lived, these diet fads are a positive trend for this sector as Americans ultimately turn to professionals to help them meet their weight loss goals.^[29][30]

In Western Europe, sales of weight-loss products, excluding prescription medications, topped £900 million ($1.4 billion) in 2009.^[30]

See also [edit]

References [edit]

Notes

This article includes a list of references, but its sources remain unclear because it has insufficient inline citations. Please help to improve this article by introducing more precise citations. (February 2010)

External links [edit]

• Weight-loss advertising: An Analysis of Current Trends. U.S. Federal Trade Commission (September 2002)
• Losing Weight Safely U.S. Food and Drug Administration
• Weight-control Information Network U.S. National Institutes of Health
• "Eat Like Our Ancestors". An Interview with Harvard’s Deirdre Barrett US News and World Report, 29 June 2007
• Weight loss at the Open Directory Project