Weight loss

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

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. Note that untreated type 1 diabetes mellitus will usually not produce weight loss, as these patients get acutely ill before they have time to lose weight.

In addition to weight loss due to a reduction in fat and lean mass, illnesses such as diabetes, certain medications, lack of fluid intake and other factors can trigger fluid loss. Fluid loss in addition to reduction in fat and lean mass exacerbates the risk for cachexia.

Infections such as HIV may alter metabolism, leading to weight loss.

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

Recent research has shown fidgeting to result in significant weight loss.

Causes of unintentional weight loss

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 should be considered in any patient presenting with unexplained weight loss.

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, a fairly common and well-known disease caused by intolerance of gluten, 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

Intentional weight loss

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

Therapeutic weight loss, in individuals who are overweight or obese, can decrease the likelihood of developing diseases such as diabetes, heart disease, high blood pressure, stroke, osteoarthritis, and certain types of cancer.

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

Weight loss occurs when an individual is in a state of negative energy balance: when the body is exerting 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.

It is not uncommon for some people who are currently at their ideal body weight to seek additional weight loss in order to improve athletic performance, and/or meet required weight classification for participation in a sport. However, others may be driven by achieving a more attractive body image. Notably, 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.

There are many diet plans and recipes that can be helpful for weight loss. While some are classified as unhealthy and potentially harmful to one's general health, others are recommended by specialists. Diet plans are generally designed according to the recommended caloric intake but it is important to note that the most successful diets are those that simultaneously promote physical activity. There are many dietary programs that claim to be efficient in helping overweight individuals to lose weight with no effort. However, the long-term efficacy of these plans is questionable.

Intentional weight loss is, in most cases, achieved with the help of diets since dietary restriction is generally more manageable than making a significant change in one's lifestyle (although weight loss is generally associated with some degree of change in lifestyle habits) or beginning to practice a sport. In that regard, a wide variety of 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. Notably, daily calorie consumption for dietary purposes vary depending on a number of factors including, age, gender, weight loss goals, and many more. For instance, nutritionists suggest that a minimum of 1,200 daily calories should be consumed by women in order to maintain health. The daily calorie consumption by men, on the other hand, could approach 1,500. It is important to note that these recommendations primarily target relatively healthy individuals who seek weight loss for a better body tonus. However, individuals whose obesity places them at an increased risk for diabetes, heart disease, or other conditions, may follow a more strict diet, but only under the close monitoring of a physician and/or specialist. In some cases, obese individuals may need to restrict their daily calorie intake to 800 or even 500.According to the FDA, healthy individuals seeking to maintain their weight, should consume 2,000 calories per day.

Low-calorie regimen diets are also referred to as balanced 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. Therefore, from the total number of allotted daily calories, 55% should come from carbohydrates, 15% from protein, and 30% from fats with no more than 10% of total fat coming from saturated forms. For instance, a 1,200 calorie diet would consist of no more than 660 calories from carbohydrates, 180 from protein, and 360 from fat. Although counting calories seems difficult altogether, the long term benefits of calorie restriction are many. After reaching the desired body weight, the amount of 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, 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.

The golden rule in weight loss is to avoid foods that are high in fats and sugars, both of which contribute to increased body mass and are detrimental to the overall health. Further, weight gain has been associated with excessive alcohol consumption.  Depression, stress or boredom may also contribute to weight increase,  and in these cases, individuals are advised to seek medical help. A 2010 study found that dieters who got a full night's sleep more than doubled the amount of fat lost compared to sleep-deprived dieters.

Therapeutic weight loss techniques

See also: Obesity#Management and Bariatrics

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. Physicians will usually recommend that their overweight patients combine a reduction of processed foods and caloric content of the diet with an increase in physical activity.

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. Application of such medications, however, should only be performed under the strict supervision of a physician and/or specialist.

Weight Loss Coaching is rapidly growing in popularity in the United States, with the number of available coaches nearly doubling since 2000. Finally, surgery (i.e. bariatric surgery) may be used in more severe cases to artificially reduce the size of the stomach, thus limiting the intake of food energy.

Dietary supplements, though widely used, are not considered a healthy option for weight loss. Even though a wide array of these products is available to the public, very few are effective long term.

Bariatric surgery is usually considered a last resort in treating severe obesity and it consists of two main procedures: gastric bypass and gastric banding.

Crash dieting

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. Crash dieting can be dangerous to health and this method of weight loss is not recommended by medical doctors.

Crash dieting is not the same as intermittent fasting, in which the individual periodically abstains from food (e.g., every other day).

Weight loss industry

There is a substantial market for products which promise to make weight loss easier, quicker, cheaper, more reliable, or less painful. These include books, CDs, cremes, lotions, pills, rings and earrings, body wraps, body belts and other materials, not to mention fitness centers, personal coaches, weight loss groups, and food products and supplements. US residents in 1992 spent an estimated $30 billion a year on all types of diet programs and products, including diet foods and drinks.

Between $33 billion and $55 billion is spent annually on weight loss products and services, including medical procedures and pharmaceuticals, with weight loss centers garnering between 6 percent and 12 percent of total annual expenditure. 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.

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

(source:wikipedia)