Obesity is defined as an abnormal or excessive accumulation of adipose tissue in the body, resulting in adverse effects on the health and wellbeing of the individual.3 In clinical practice, a useful measure of obesity is the body mass index (BMI). It gives a reasonable approximation of adiposity and indicator of health. BMI is derived by dividing an individual’s weight in kilograms by height in meters squared (kg/m2). Adults with a BMI between 25 and 29.9 kg/m2 are categorised as having overweight or preobesity, and those with a BMI of 30 kg/m2 or over are categorised as having obesity (Table 1).3 The BMI cut-off points are, however, not applicable to all ethnic groups, people at extremes of age and those with excess muscularity and height.
Diagnosing someone as having obesity can have psychological consequences. The word obesity is loaded with stigma, blame and shame. Weight stigma arises from the misunderstanding of obesity drivers. Weight stigma can trigger physiological and behavioural changes linked to poor metabolic health, increased weight gain and exercise avoidance.4-6 Using compassionate terms and discussing weight from a health perspective can help alleviate these negative effects. Using words like ‘being well above a healthy weight’ is preferred rather than ‘extremely obese’ or ‘fat’. However, not discussing weight has equally detrimental outcomes.
Obesity as a disease and risk factor
Obesity is regarded as a disease in its own right. It is also a risk factor for a large number of chronic, metabolic and mechanically induced disorders, the risk of which increases on a continuum with increasing adiposity. It is not only the amount but also the distribution of adipose tissue that underlies the health risks and diseases associated with obesity. Waist circumference, a surrogate marker of visceral fat, has been shown to be a more sensitive measure of long-term health risks (Table 2).3 Waist circumference (really an abdominal circumference at a defined level) should be measured mid-way between the lowest rib and the upper border of the iliac crest. This position can sometimes be difficult to find in an individual with obesity. Always look from the side, make sure the tape measure is level and have it directly on the skin to get the most accurate and repeatable results.
Goals of obesity management
Any obesity management plan should be structured to include both an active weight loss phase and a weight maintenance phase. Lifestyle modification – dietary change, alterations in physical activity and behaviour modification – should be the main therapeutic approaches in the management of obesity. Effective weight management is defined as a weight loss of 5 to 10% of body weight that is maintained for at least two years. Health benefits associated with moderate weight loss are outlined in Box 1.7
Not all patients will be ready or willing to lose weight despite their weight putting them at risk of medical disorders. However, a recent international study investigating perceptions, attitudes, behaviours and barriers to effective care in adults with obesity and healthcare professionals identified a dichotomy between patients and healthcare professionals.1 More than two-thirds (65%) of patients wanted their healthcare professional to talk about their weight. However, on average, they had to wait six years between starting to struggle with their weight and having such a conversation. The top reason (71%) given by healthcare providers why weight was not discussed was the perception that the patient was not interested in losing weight. In contrast, only 7% of patients reported not being interested. Most patients are interested and want their healthcare professional to discuss their weight, and the sooner this conversation takes place, the better.