What is Obesity
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Definition of Obesity

Obesity can be defined as a chronic adverse condition due to an excess amount of body fat. While there are numerous methods to determine the relative amount of body fat, the most widely used method to determine obesity is the BMI = (weight in kg)/(height in meters)


Risk factors


  • Secondary obesity is uncommon, but hypothyroidism can be associated with abnormal weight gain.
  • Secondary obesity is uncommon, but hypercortisolism can be associated with excess weight.
corticosteroid therapy
  • Weight gain is associated with long-term corticosteroid use.


age ≥40
  • The prevalence of obesity is not equal across age groups; there appears to be a peak in the prevalence in the fifth decade, followed by a plateau in the sixth through eighth decades, with a subsequent tapering in the prevalence after the eighth decade.
peri- and postmenopause
  • Weight gain and abdominal redistribution of fat after menopause has been well described, but is not universal and has a complex relationship with environmental factors.Hormone replacement therapy (HRT) is not associated with further weight gain. HRT actually may prevent weight gain and abdominal fat redistribution.
prior pregnancy
  • There may be a weak association with obesity and parity. This association is confounded by contributing cultural, environmental and socioeconomic factors.
  • Some investigators have noted that the prevalence of obesity is higher in married people than in single people. While there are a number of theories to explain this, the association is not well understood.
sleep deprivation
  • Sleep deprivation, whether voluntary or induced (e.g., shift working), has been associated with weight gain and obesity.
hx of tobacco smoking
  • Obesity and smoking are commonly observed in association, but it is unclear whether smoking might be a risk factor for obesity. Some studies suggest smoking cessation may also be a risk factor for weight gain.
less formal education
  • In large epidaemiological studies, the prevalence of obesity has been noted to be increased in groups with less formal education.
poor in utero nutrition
  • Long-term epidaemiological studies have noted a correlation between poor maternal nutrition during pregnancy (mostly manifested by low birth weight) and obesity in adulthood.
low socioeconomic status
  • In most large epidemiological studies in the U.S.A. and Europe, the prevalence of obesity is higher in groups with low socioeconomic status.
sedentary lifestyle
  • Since the relationship between obesity and a sedentary lifestyle remains a loose association, a sedentary lifestyle is characterized as a weak risk factor for obesity.
television watching and video games >2 to 3 hours daily
  • Excessive television watching and video game playing generally are viewed as markers of a sedentary lifestyle and, not surprisingly, people (particularly children) who watch or play an excessive amount of television or video games have a higher incidence of obesity than people who are more active.
diet high in sugar, cholesterol, fat and fast food
  • Dietary composition, or the choice of which types of foods to eat, has been implicated as a risk factor for obesity. Not all people whose diet is dominated by these choices become obese; the precise contribution of dietary choice to the development of obesity is difficult to quantify.
heavy alcohol intake (>2 drinks per day)
  • Heavy alcohol consumption (>2 drinks per day) has been positively associated with obesity, although moderate alcohol consumption (i.e., 1 to 2 drinks per day) has been described as having a modest protective effect against obesity.
binge-eating disorder
  • One of many obesogenic behaviors loosely associated with obesity.
night eating syndrome
  • One of many obesogenic behaviors loosely associated with obesity.
leptin deficiency
  • Leptin deficiency is a rare cause of inherited obesity.
antidepressant therapy
  • Some reports correlate weight gain with anti-depressant use.
anti psychotic therapy
  • Obesity is associated with some anti-psychotic medicine.
beta-blocker therapy
  • Some correlation has been described between beta-blocker use and weight gain.
adjuvant breast cancer therapy
  • Side effects of adjuvant therapies for breast cancer can include weight gain.
psychiatric diagnosis
  • While there may be an association between obesity and psychiatric diagnosis, the importance of this latter risk factor is not clear because many, if not most, patients with a diagnosis such as schizophrenia or depression are on medication, which is associated with obesity.