Intentional weight loss is the loss of total body mass as a result of efforts to improve fitness and health, or to change appearance through slimming. Weight loss is the main treatment for obesity,[1][2][3] and there is substantial evidence this can prevent progression from prediabetes to type 2 diabetes with a 7-10% weight loss and manage cardiometabolic health for diabetic people with a 5-15% weight loss.[4]

Weight loss in individuals who are overweight or obese can reduce health risks,[5] increase fitness,[6] and may delay the onset of diabetes.[5] It could reduce pain and increase movement in people with osteoarthritis of the knee.[6] Weight loss can lead to a reduction in hypertension (high blood pressure), however whether this reduces hypertension-related harm is unclear.[5][failed verification] Weight loss is achieved by adopting a lifestyle in which fewer calories are consumed than are expended.[7] Depression, stress or boredom may contribute to weight increase,[8] 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.[9][10] Though hypothesized that supplementation of vitamin D may help, studies do not support this.[11] The majority of dieters regain weight over the long term.[12] According to the UK National Health Service and the Dietary Guidelines for Americans, 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.[13][7]

In order for weight loss to be permanent, changes in diet and lifestyle must be permanent as well.[14][15][16] There is evidence that counseling or exercise alone do not result in weight loss, whereas dieting alone results in meaningful long-term weight loss, and a combination of dieting and exercise provides the best results.[17] Meal replacements, orlistat and very-low-calorie diet interventions also produce meaningful weight loss.[18]

Techniques

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 recommends that people combine a reduction of processed foods high in saturated fats, sugar and salt[19] and caloric content of the diet with an increase in physical activity.[20] Self-monitoring of diet, exercise, and weight are beneficial strategies for weight loss,[21][22] particularly early in weight loss programs.[23] Research indicates that those who log their foods about three times per day and about 20 times per month are more likely to achieve clinically significan.[24]

The cardboard packaging of two medications used to treat obesity. Orlistat is shown above under the brand name Xenical in a white package with Roche branding. Sibutramine is below under the brand name Meridia. Orlistat is also available as Alli in the United Kingdom. The A of the Abbott Laboratories logo is on the bottom half of the package.

Orlistat (Xenical) the most commonly used medication to treat obesity and sibutramine (Meridia) a withdrawn medication due to cardiovascular side effects

An increase in fiber intake is 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.[25] Both can be effective at limiting the intake of food energy by reducing the size of the stomach, but as with any surgical procedure both come with their own risks[26] that should be considered in consultation with a physician. Dietary supplements, though widely used, are not considered a healthy option for .[27] Many are available, but very few are effective in the long term.[28]

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.[29][30][31][32] In 1996, a study found that cognitive-behavioral therapy was more effective for weight reduction if reinforced with hypnosis.[30] Acceptance and commitment therapy, a mindfulness approach to, has been demonstrated as useful.[33] Herbal medications have also been suggested; however, there is no strong evidence that herbal medicines are effective.[34]

Weight loss industry

There is a substantial market for products which claim 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, clinics, personal coaches, weight loss groups, and food products and supplements.[35]

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 centers taking between 6 and 12 percent of total annual expenditure. Over $1.6 billion per year was spent on weight-loss supplements. About 70 percent of Americans’ dieting attempts are of a self-help nature.[36][37]

In Western Europe, sales of  products, excluding prescription medications, topped €1,25 billion (£900 million/$1.4 billion) in 2009.

The scientific soundness of commercial diets by commercial weight management organizations varies widely, being previously non-evidence-based, so there is only limited evidence supporting their use, because of high attrition rates. Commercial diets result in modest  in the long term, with similar results regardless of the brand,and similarly to non-commercial diets and standard care. Comprehensive diet programs, providing counseling and targets for calorie intake, are more efficient than dieting without guidance (“self-help”),[38][46][45] although the evidence is very limited.[43] The National Institute for Health and Care Excellence devised a set of essential criteria to be met by commercial weight management organizations to be approved.[41]

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