Weight loss, in the context of medicine, health, or physical fitness,
refers to a reduction of the total body mass, due to a mean loss of
fluid, body fat or adipose tissue or lean mass, namely bone mineral
deposits, muscle, tendon, and other connective tissue.
Weight loss can
either occur unintentionally due to malnourishment or an underlying
disease or arise from a conscious effort to improve an actual or
perceived overweight or obese state. "Unexplained" weight loss that is
not caused by reduction in calorific intake or exercise is called
cachexia and may be a symptom of a serious medical condition.
Intentional weight loss is commonly referred to as slimming.
1.2 Permanent weight loss
Weight loss industry
2.2.3 Social conditions
3 Health effects
4 See also
6 External links
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
Weight loss in individuals who are overweight or obese can
reduce health risks, increase fitness, and may delay the onset
of diabetes. It could reduce pain and increase movement in people
with osteoarthritis of the knee.
Weight loss can lead to a
reduction in hypertension (high blood pressure), however whether this
reduces hypertension-related harm is unclear.[not in citation
Weight loss occurs when the body is expending more energy in work and
metabolism than it is absorbing from food or other nutrients. It will
then use stored reserves from fat or muscle, gradually leading to
weight loss. For athletes seeking to improve performance or to meet
required weight classification for participation in a sport, it is not
uncommon to seek additional weight loss even if they are already at
their ideal body weight. Others may be driven to lose weight to
achieve an appearance they consider more attractive. However, 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
Low-calorie 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. For instance, a recommended 1,200
calorie diet would supply about 660 calories from carbohydrates, 180
from protein, and 360 from fat. Some studies suggest that increased
consumption of protein can help ease hunger pangs associated with
reduced caloric intake by increasing the feeling of satiety.
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, 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.
Weight gain has been associated with excessive consumption of fats,
(added) sugars, refined carbohydrates in general, and 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 lost more than twice as much fat
as sleep-deprived dieters.
Though hypothesized that supplementation of vitamin D may help,
studies do not support this. The majority of dieters regain weight
over the long term.
According to 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. According to the U.S. Food and Drug
Administration (FDA), healthy individuals seeking to maintain their
weight should consume 2,000 calories (8.4 MJ) per day.[citation
See also: Management of obesity
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 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
Bariatric surgery may be indicated in cases of severe
obesity. Two common bariatric surgical procedures are gastric bypass
and gastric banding. 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 that should be
considered in consultation with a physician. Dietary supplements,
though widely used, are not considered a healthy option for weight
loss. Many are available, but very few are effective in the long
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. In 1996 a
study found that cognitive-behavioral therapy (CBT) was more effective
for weight reduction if reinforced with hypnosis. Acceptance and
Commitment Therapy ACT, a mindfulness approach to weight loss, has
also in the last few years been demonstrating its usefulness.
Permanent weight loss
In order for weight loss to be permanent, changes in diet and
lifestyle must be permanent as well. Short-term dieting has not been
shown to produce either long term weight loss or better health, and
may even be counterproductive.
Weight loss industry
The examples and perspective in this section deal primarily with the
United States and do not represent a worldwide view of the subject.
You may improve this article, discuss the issue on the talk page, or
create a new article, as appropriate. (December 2010) (Learn how and
when to remove this template message)
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,
clinics, personal coaches, weight loss groups, and food products and
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.
In Western Europe, sales of weight-loss products, excluding
prescription medications, topped €1,25 billion (£900 million/$1.4
billion) in 2009.
Unintentional weight loss may result from loss of body fats, loss of
body fluids, muscle atrophy, or even a combination of these.
It is generally regarded as a medical problem when at least 10% of a
person's body weight has been lost in six months or 5% in the
last month. Another criterion used for assessing weight that is
too low is the body mass index (BMI). However, even lesser amounts
of weight loss can be a cause for serious concern in a frail elderly
Unintentional weight loss can occur because of an inadequately
nutritious diet relative to a person's energy needs (generally called
malnutrition). Disease processes, changes in metabolism, hormonal
changes, medications or other treatments, disease- or
treatment-related dietary changes, or reduced appetite associated with
a disease or treatment can also cause unintentional weight
loss. Poor nutrient utilization can lead to
weight loss, and can be caused by fistulae in the gastrointestinal
tract, diarrhea, drug-nutrient interaction, enzyme depletion and
Continuing weight loss may deteriorate into wasting, a vaguely defined
condition called cachexia.
Cachexia differs from starvation in
part because it involves a systemic inflammatory response. It is
associated with poorer outcomes. In the advanced stages of
progressive disease, metabolism can change so that they lose weight
even when they are getting what is normally regarded as adequate
nutrition and the body cannot compensate. This leads to a condition
called anorexia cachexia syndrome (ACS) and additional nutrition or
supplementation is unlikely to help. Symptoms of weight loss from
ACS include severe weight loss from muscle rather than body fat, loss
of appetite and feeling full after eating small amounts, nausea,
anemia, weakness and fatigue.
Serious weight loss may reduce quality of life, impair treatment
effectiveness or recovery, worsen disease processes and be a risk
factor for high mortality rates.
Malnutrition can affect every
function of the human body, from the cells to the most complex body
muscle strength (including respiratory muscles);
renal capacity and depletion leading to water and electrolyte
In addition, malnutrition can lead to vitamin and other deficiencies
and to inactivity, which in turn may pre-dispose to other problems,
such as pressure sores.
Unintentional weight loss can be the characteristic leading to
diagnosis of diseases such as cancer and type 1 diabetes.
In the UK, up to 5% of the general population is underweight, but more
than 10% of those with lung or gastrointestinal diseases and who have
recently had surgery. According to data in the UK using the
Malnutrition Universal Screening Tool ('MUST'), which incorporates
unintentional weight loss, more than 10% of the population over the
age of 65 is at risk of malnutrition. A high proportion (10-60%)
of hospital patients are also at risk, along with a similar proportion
in care homes.
Disease-related malnutrition can be considered in four categories:
Poor appetite can be a direct symptom of an illness, or an illness
could make eating painful or induce nausea. Illness can also cause
Inability to eat can result from: diminished consciousness or
confusion, or physical problems affecting the arm or hands, swallowing
or chewing. Eating restrictions may also be imposed as part of
treatment or investigations. Lack of food can result from: poverty,
difficulty in shopping or cooking, and poor quality meals.
Impaired digestion &/or absorption
This can result from conditions that affect the digestive system.
Changes to metabolic demands can be caused by illness, surgery and
Excess nutrient losses
Losses from the gastrointestinal can occur because of symptoms such as
vomiting or diarrhea, as well as fistulae and stomas. There can also
be losses from drains, including nasogastric tubes.
Other losses: Conditions such as burns can be associated with losses
such as skin exudates.
Weight loss issues related to specific diseases include:
As chronic obstructive pulmonary disease (COPD) advances, about 35% of
patients experience severe weight loss called pulmonary cachexia,
including diminished muscle mass. Around 25% experience moderate
to severe weight loss, and most others have some weight loss.
Greater weight loss is associated with poorer prognosis. Theories
about contributing factors include appetite loss related to reduced
activity, additional energy required for breathing, and the difficulty
of eating with dyspnea (labored breathing).
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,
hepatobiliary (hepatocellular carcinoma, pancreatic cancer), ovarian,
hematologic or lung malignancies.
HIV often experience weight loss, and it is associated
with poorer outcomes. Wasting syndrome is an AIDS-defining
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 include: celiac disease, peptic
ulcer disease, inflammatory bowel disease (crohn's disease and
ulcerative colitis), pancreatitis, gastritis, diarrhea and many other
Infection. Some infectious diseases can cause weight loss. Fungal
illnesses, endocarditis, many parasitic diseases, AIDS, and some other
subacute or occult infections may cause weight loss.
Renal disease. Patients who have uremia often have poor or absent
appetite, vomiting and nausea. This can cause weight loss.
Cardiac disease. Cardiovascular disease, especially congestive heart
failure, may cause unexplained weight loss.
Connective tissue disease
Neurologic disease, including dementia
Oral, taste or dental problems (including infections) can reduce
nutrient intake leading to weight loss.
Medical treatment can directly or indirectly cause weight loss,
impairing treatment effectiveness and recovery that can lead to
further weight loss in a vicious cycle.
Many patients will be in pain and have a loss of appetite after
surgery. Part of the body's response to surgery is to direct
energy to wound healing, which increases the body's overall energy
requirements. Surgery affects nutritional status indirectly,
particularly during the recovery period, as it can interfere with
wound healing and other aspects of recovery. Surgery directly
affects nutritional status if a procedure permanently alters the
Enteral nutrition (tube feeding) is often
needed. However a policy of 'nil by mouth' for all
gastrointestinal surgery has not been shown to benefit, with some
suggestion it might hinder recovery.
Early post-operative nutrition is a part of Enhanced Recovery After
Surgery protocols. These protocols also include carbohydrate
loading in the 24 hours before surgery, but earlier nutritional
interventions have not been shown to have a significant impact.
Some medications can cause weight loss, while others can cause
Social conditions such as poverty, social isolation and inability to
get or prepare preferred foods can cause unintentional weight loss,
and this may be particularly common in older people. Nutrient
intake can also be affected by culture, family and belief systems.
Ill-fitting dentures and other dental or oral health problems can also
affect adequacy of nutrition.
Loss of hope, status or social contact and spiritual distress can
cause depression, which may be associated with reduced nutrition, as
Obesity § Effects on health
Obesity increases health risks, including diabetes, cancer,
cardiovascular disease, high blood pressure, and non-alcoholic fatty
liver disease, to name a few. Reduction of obesity lowers those risks.
A 1-kg loss of body weight has been associated with an approximate
1-mm Hg drop in blood pressure.
Cigarette smoking for weight loss
Failure to thrive
Online weight loss plans
Weight loss effects of water
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