|Classification and external resources|
The overweight range according to the Body Mass Index (BMI) is the area on the chart where BMI > 25.
A healthy body requires a minimum amount of fat for the proper functioning of the hormonal, reproductive, and immune systems, as thermal insulation, as shock absorption for sensitive areas, and as energy for future use. But the accumulation of too much storage fat can impair movement and flexibility, and can alter the appearance of the body.
- 1 Classification
- 2 Health-related implications
- 3 Causes
- 4 Treatment
- 5 See also
- 6 References
- 7 External links
The degree to which a person is overweight is generally described by body mass index (BMI). Overweight is defined as a BMI of 25 or more, thus it includes pre-obesity defined as a BMI between 25 and 30 and obesity as defined by a BMI of 30 or more. Pre obese and overweight however are often used interchangeably thus giving overweight a common definition of a BMI of between 25 -30. There are however several other common ways to measure the amount of adiposity or fat present in an individual's body.
- The body mass index (BMI) is a measure of a person's weight taking into account their height. It is given by the formula: BMI equals a person's weight (mass) in kilograms divided by the square of the person's height in metres. The units therefore are kg/m2 but BMI measures are typically used and written without units.
- BMI provides a significantly more accurate representation of body fat content than simply measuring a person's weight. It is only moderately correlated with both body fat percentage and body fat mass (R2 of 0.68). It does not take into account certain factors such as pregnancy or bodybuilding; however, the BMI is an accurate reflection of fat percentage in the majority of the adult population.
- The body volume index (BVI) was devised in 2000 as a computer, rather than manual, measurement of the human body for obesity and an alternative to the BMI
- Body volume index uses 3D software to create an accurate 3D image of a person so BVI can differentiate between people with the same BMI rating, but who have a different shape and different weight distribution.
- BVI measures where a person's weight and the fat are located on the body, rather than total weight or total fat content and places emphasis on the weight carried around the abdomen, commonly known as central obesity. There has been an acceptance in recent years that abdominal fat and weight around the abdomen constitute a greater health risk.
- The person's weight is measured and compared to an estimated ideal weight. This is the easiest and most common method, but by far the least accurate, as it only measures one quantity (weight) and often does not take into account many factors such as height, body type, and relative amount of muscle mass.
- Skinfold calipers or "pinch test"
- The skin at several specific points on the body is pinched and the thickness of the resulting fold is measured. This measures the thickness of the layers of fat located under the skin, from which a general measurement of total amount of fat in the body is calculated. This method can be reasonably accurate for many people, but it assumes particular fat distribution patterns over the body—which may not apply to all individuals, and does not account for fat deposits not directly under the skin. Also, as the measurement and analysis generally involves a high degree of practice and interpretation, an accurate result requires that a professional perform it. It cannot generally be done by patients themselves.
- A small electrical current is passed through the body to measure its electrical resistance. As fat and muscle conduct electricity differently, this method can provide a direct measurement of the body fat percentage, in relation to muscle mass. In the past, this technique could only be performed reliably by trained professionals with specialized equipment, but it is now possible to buy home testing kits that let people do this themselves with a minimum of training. Despite the improved simplicity of this process over the years, however, a number of factors can affect the results, including hydration and body temperature, so it still needs some care when taking the test to ensure that the results are accurate.
- Hydrostatic weighing
- Considered one of the more accurate methods of measuring body fat, this technique involves complete submersion of a person in water, with special equipment to measure the person's weight while submerged. This weight is then compared with "dry weight" as recorded outside the water to determine overall body density. As fat is less dense than muscle, careful application of this technique can provide a reasonably close estimate of fat content in the body. This technique does, however, require expensive specialized equipment and trained professionals to administer it properly.
- Originally developed to measure bone density, DEXA imaging is also used to precisely determine body fat content by using the density of various body tissues to identify which portions of the body are fat. This test is generally considered very accurate, but requires a great deal of expensive medical equipment and trained professionals to perform.
The most common method for discussing this subject and the one used primarily by researchers and advisory institutions is BMI. Definitions of what is considered overweight vary by ethnicity. The current definition proposed by the US National Institutes of Health (NIH) and the World Health Organization (WHO) designates whites, Hispanics and blacks with a BMI of 25 or more as overweight. For Asians, overweight is a BMI between 23 and 29.9 and obesity for all groups is a BMI of 30 or more.
BMI, however, does not account extremes of muscle mass, some rare genetic factors, the very young, and a few other individual variations. Thus it is possible for an individuals with a BMI of less than 25 to have excess body fat, while others may have a BMI that is significantly higher without falling into this category. Some of the above methods for determining body fat are more accurate than BMI but come with added complexity.
If an individual is overweight and has excess body fat it could, but won't always, create or lead to health risks. Reports are surfacing, however, that being mildly overweight to slightly obese – BMI being between 24 and 31.9 – may be actually beneficial and that people with BMI between 24 and 31.9 could actually live longer than normal weight or underweight persons.
While the negative health outcomes associated with obesity are accepted within the medical community, the health implications of the overweight category are more controversial. The generally accepted view is that being overweight causes similar health problems to obesity, but to a lesser degree. Adams et al. estimated that the risk of death increases by 20 to 40 percent among overweight people, and the Framingham heart study found that being overweight at age 40 reduced life expectancy by three years. A review in 2013 came to the result that being overweight significantly increases the risk of oligospermia and azoospermia in men.
Flegal et al., however, found that the mortality rate for individuals who are classified as overweight (BMI 25 to 30) may actually be lower than for those with an "ideal" weight (BMI 18.5 to 25).
Being overweight does not increase mortality in older people.
Prevalence per country
- Eating disorders (such as binge eating)
- Genetic predisposition
- Hormonal imbalances (e.g. hypothyroidism)
- Insufficient or poor-quality sleep
- Limited physical exercise and sedentary lifestyle
- Poor nutrition
- Metabolic disorders, which could be caused by repeated attempts to lose weight by weight cycling
- Psychotropic medication (e.g. olanzapine)
- Smoking cessation and other stimulant withdrawal
People who have insulin dependant diabetes and chronically overdose insulin may gain weight, while people who already are overweight may develop insulin tolerance, and in the long run type II diabetes.
|This section may require copy-editing for grammar and idiomaticity. (July 2013)|
The etiology and the difficulty of one's overweight condition or level of obesity may be different for different reasons. Treatment must be suited to the nature of an individual's body anatomy and physiology with a focus on contributing factors.
The physician or dietitian may perform a BMI calculation, sampling fat percentage of the body, measuring posterior, arm, or stomach. The clinician may recommend tests for hormonal and other biochemical abnormalities in glucose, insulin, cholesterol, thyroid hormones, sex hormones, SHBG and other proteins, cortisol (associated with Cushing's syndrome), triglycerides, HCG, and in acute cases ghrelin (also known as the "hunger" hormone) and leptin (sometimes known as the "satiety hormone") though satiety is associated with some other major factors that aren't necessarily hormonal or molecular.
Some evidence suggests that for merely overweight patients, the health effects of attempting to lose weight may actually be more detrimental than simply remaining overweight.
General treatment in cases of overweight
With the accumulation of knowledge about its neuroendocrine, gastroenterological, nutritional, and psychological (mainly cognitive and behavioral), and environmental causes, obesity, at least in its acute versions, is no longer understood as a problem solely dependent on the obese. It is now known that independent factors, genetic and epigenetic alike, resemble an infrastructure of a decent number of obesity cases, in such a way that the obese have little control whatsoever of their condition. In cases of mild obesity, or overweight, most cases are more easily self-regulated, so that self-care is easier to instill, and in most cases efficient, if implemented correctly.
General treatments are a proper diet, and tailored exercise program (in cases of ability), and sometimes some supplements such as orlistat (lipase inhibitor), caffeine, or others, usually given by a physician, or a dietitian.
In the case of extreme diets, the body goes into an emergency regimen and lowers its metabolic rate, with the result that after the diet, it uses fewer calories for energy production and gathers more to form fat in ddipocytes. Extreme diet usually ends with the individual falling back to previous eating habits and weight, almost always in a repetitive form—a phenomenon known as the yo-yo effect. Dietitians generally recommend eating several balanced meals dispersed through the day, with a combination of progressive, primarily aerobic, physical exercise. Also it should be mentioned that non-overweight people have a higher chance to stay as such, because of higher levels of hormones such as Adiponectin, which is considered to play a positive role in fatty-acid metabolism.
Because these general treatments are trivial and could actually help almost any case of obesity, they are common in all its levels, and resemble the most basic form of treat even in worst cases that demands more progressive medical intervention, as described later.
Specific causes for overweight
Inability to make efficient aerobic exercise
Besides diet, overweight (tendency to gain weight, BMI: 25.0 – 29.9) in an allegedly healthy man could be agitated or worsened by the inability (which is treatable in most cases) to make efficient aerobic exercise. A common cause for this is a chronic pathology or the accumulation (or multiplicative effect) of several associated pathologies in the lower respiratory tract or upper respiratory tract that aren't necessarily fatal. ?These cause an inability to breathe efficiently from the nose in normal conditions and especially during exercise. So much so, that an individual who runs for more than a few minutes experiences a suffocating feeling in the throat, or even lactic acidosis in the legs. Little nasal airflow could be derived from pathologies as turbinate hyperthrophy and nasal septum deviation, allergic, and vasomotor rhinitis, asthma, especially exertion asthma, and exercise-induced bronchospasm. Such pathologies are easily diagnosed at an otolaryngologist or pulmonologist, respectively. It is important to note that such problems themselves could induce another problem: lactic acidosis. In this case, one who experiences relatively low intake of oxygen because of problematic breathing during aerobic exercise might not have enough of it to cause lactic acid oxidation, and therefore, would have symptoms such as a feeling of general or specific abnormal (muscle) pain, hyperventilation, fatigue, weakness, and heart irregularities while doing their aerobic activity in cases in which inability to do efficient aerobic exercise (from the aforementioned cases for example) is the main reason for gaining weight (from fat storage), whereas treating it could relieve overweight.
Metabolic or Hormonal pathology or idiopathy
Some who are considered healthy by conventional standards might have, for yet unknown reasons, a metabolic pattern that lets them store more fat than normal weight people (BMI 18.5 – 24.9). The popular solution for this problem is a carefully planned and sophisticated diet and exercise program, under the supervision of a licensed dietitian. Some might acquire cognitive and or behavioral therapy from a medical psychologist.
There are many environmental factors that could lead to weight gain.
A lack or money or time to devote to exercise due to other commitments, such as work or family, or an inability to exercise, due to living in an environment away from public parks, gyms, or a supportive network of people.
A job that involves working with food (especially fast food could also contribute to weight gain.
Some particular manifestations of overweight, such as lipomastia or waist or belly fat, are treated with targeted liposuction. Such a treatment is useful only in cases of overweight, and not in cases of obesity.
In obese people (who generally have more complicated issues), the frequency of hormonal or metabolic failings is higher. In relatively mild cases of obesity, which are still harder than regular overweight, specific obesity medication, or HRT could be useful for the patients. In extreme cases bariatric surgery is considered. The NIH recommends to perform such surgery only those with BMI above 40, or above 35.0 if they suffer from a serious co-morbid condition such as diabetes. Indeed, even in progressive obesity, many cases would demand a diet as balanced as possible, alongside the medical treatment.
Those who are overweight or obese often consult psychologists (such as medical and sport psychologists, and maybe others), to provide them with psychological and practical advice in order to lose weight. Supervised learning and implementation of cognitive and behavioral techniques may help to reduce as much as possible the likelihood of failing in the weight-loss process.
Being overweight could bring emotional distress, harassment, and impair the intimate functioning in some cases, if not many, thus detracting some of the joy and opportunities of the individual and endanger them and mentally and physically (albeit, not harshly as in severe forms of obesity).
Sometimes treatment of overweight could indeed be demanding, and require considerable mental and financial resources just for the potentially exhausting investigation into the factors causing the overweight, especially when it involves bureaucratic and systematic obstacles to name a few.
Understanding the importance of treating obesity may itself play a contributing variable to the success of the process of removing individual excessive amount of body fat and increase the chances of achieving that target.
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- See for example: "What are the guidelines for percentage of body fat loss?". Ask the Expert Blog. American Council on Exercise (ACE). December 2, 2009.
- Obesity Epidemic: U.S. Temporal Trends 1985–2004
- Ranking of Most Overweight Countries in the World 2005
- World Health Organization fact sheet on obesity and overweight
- Ideal Weight Calculator