Weight loss today is a globally prevalent problem with people across the globe dealing with obesity. Healthy eating prevents and controls health problems such as heart disease, high blood pressure, type-2 diabetes, and types of cancer.
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 and/or lean mass, namely bone mineral deposits, muscle, tendon, and other connective tissue. Many people substitute food with dietary supplements for weight loss.
There could be unintentional weight loss due to malnourishment or some underlying disease or it could 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.
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. Body Mass Index (BMI) is another criterion for assessing weight that is too low. However, in a frail elderly person even lesser amount of weight loss can be a cause for serious concern.
Malnutrition is an unintentional weight loss occurring because of an inadequately nutritious diet relative to a person’s energy needs. 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. Varied medical conditions like fistulae in the gastrointestinal tract, diarrhea, drug-nutrient interaction, enzyme depletion and muscle atrophy can lead to weight loss due to poor nutrient utilization.
A vaguely defined condition called cachexia may occur due to continuing weight loss deteriorating into wasting. 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. Severe weight loss from muscle rather than body fat, loss of appetite and feeling full after eating small amounts, nausea, anemia, weakness and fatigue are some of the symptoms of weight loss from ACS.
There are adverse effects of serious weight loss like reducing quality of life, impairing treatment effectiveness or recovery, worsening disease processes and being a risk factor for high mortality rates. Malnutrition can affect every function of the human body, from the cells to the most complex body functions, including:
- immune response
- wound healing
- muscle strength (including respiratory muscles)
- renal capacity and depletion leading to water and electrolyte disturbances
- thermoregulation, and
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.
|Impaired intake||Poor appetite can be a direct symptom of an illness, or an illness could make eating painful or induce nausea. Illness can also cause food aversion.
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.|
|Altered requirements||Changes to metabolic demands can be caused by illness, surgery and organ dysfunction.|
|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, hepatobilary (hepatocellular carcinoma, pancreatic cancer), ovarian, hematologic or lung malignancies.
- People with HIV often experience weight loss, and it is associated with poorer outcomes. Wasting syndrome is an AIDS-defining condition.
- 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 GI conditions.
- 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.
Post surgery, many patients will be in pain and have a loss of appetite. Part of the body’s response to surgery is to direct energy to wound healing, which increases the body’s overall energy requirements. During the post surgery recovery period it affects nutritional status indirectly, as it can interfere with wound healing and other aspects of recovery. If surgery permanently alters the digestive system it affects nutritional status. 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 weight gain.
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. Culture, family and belief systems can also affect the nutrient intake. 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 can fatigue. It could reduce pain and increase movement in people with osteoarthritis of the knee.
The loss of total body mass as a result of efforts to improve fitness and health, or to change appearance through slimming is Intentional weight loss. Weight loss can reduce health risks, increase fitness, and may delay the onset of diabetes for the people who are overweight and obese. Weight loss can lead to a reduction in hypertension (high blood pressure), however whether this reduces hypertension-related harm is unclear.
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. It is not uncommon for athletes to seek additional weight loss even if they are at their ideal body weight to further seek to improve performance or to meet required weight classification. Others may be driven to lose weight to achieve an appearance they consider more attractive. Health risks such as difficulty fighting off infection, osteoporosis, decreased muscle strength, trouble regulating body temperature and even increased risk of death are associated with being underweight.
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. A balanced diet regulates macronutrient consumption in addition to restricting calorie intake. 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. 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) after reaching the desired body weight. The low-calorie diets, in combination with increased physical activity, are thought to be most effective long-term, unlike crash diets, achieving 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.
Excessive consumption of fats, (added) sugars, refined carbohydrates in general, and alcohol consumption have been the factors associated with weight gain. Other factors which may contribute to weight increase are depression, stress or boredom. In these cases individuals are advised to seek medical help. A study has found that dieters who got a full night’s sleep lost more than twice as much fat as sleep-deprived dieters.
According to a study done by 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. Healthy individuals seeking to maintain their weight should consume 2000 calories (8.4 MJ) per day, according to the US Food and Drug Administration (USFDA).
Adjustments to eating patterns and increased physical activity, generally in the form of exercise are the most recommended least intrusive weight loss methods. 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.
For regulating the bowel movements an increase in fiber intake is also recommended. Use of drugs and supplements that decrease appetite, block fat absorption, or reduce stomach volume are other methods of weight loss. In cases of severe and extreme obesity bariatic surgery might even be indicated. Gastric bypass and gastric banding are two common bariatric surgical procedures. 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, are not considered a healthy option for weight loss, though widely used. Many are available, but very few are effective in the long term.
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. A research has been conducted into the use of hypnosis as a weight management alternative. It has been discovered by a study in 1996 that Cognitive-Behavioral Therapy (CBT) was more effective for weight reduction if reinforced with hypnosis. An another approach, Acceptance Commitment Therapy (ACT), that is a mindfulness approach to weight loss, has also in the last few years been demonstrating its usefulness.
Permanent Weight Loss
Changes in diet and lifestyle must be permanent as well in order for weight loss to be permanent. 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
There is a substantial market for products promising 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.
Some years back between US$33billion and $55billion had been spent annually in the USA on weight-loss products and services, including medical procedures and pharmaceuticals, with weight-loss centers taking between 6 to 12% of total expenditure. On weight-loss supplements alone over $1.6billion was spent.
In Western Europe, sales of weight-loss products, excluding prescription medications, topped £900 million ($1.4 billion).
A 1-kg loss of body weight has been associated with an approximate 1-mm Hg drop in blood pressure.