Obesity Flashcards
Define obesity.
Obesity can be defined as a chronic adverse condition due to an excess amount of body fat. The most widely used method to determine obesity is the body mass index (BMI).
The definitive test for the diagnosis of obesity remains the body mass index (BMI; obesity is defined as a BMI ≥30 kg/m²).
How do you measure BMI?
Weight divided by height squared ([weight in kg]/[height in m]²)
What is a good indicator for risk of comorbidities in obesity?
Central or abdominal obesity has a stronger association with obesity-related comorbidity so measure waist circumference
Waist circumference cut-offs in cm:
- Men: <94 (low), <102 (high), >102 (very high)
- Women: <80 (low), <88 (high), >88 (very high)
How common is obesity?
In adults ranges widely from <10% in many African and Southeast Asian countries, to between 20% and 40% in Europe and the Americas, and >40% in some Pacific islands.
More than two thirds of Americans are overweight or obese and about 7% are extremely obese (BMI>40)
How is obesity classified?
- Class I: BMI of 30 to <35
- Class II: BMI of 35 to <40
- Class III: BMI of ≥40.
Sometimes categorised as ‘extreme’ or ‘severe’ obesity.
OR
BMI classification:
- Underweight - BMI <18.5 kg/m²
- Normal - BMI 18.5 to 24.9 kg/m²
- Overweight - BMI 25.0 to 29.9 kg/m²
- Obese - BMI 30.0 to 39.9 kg/m²
- Extremely (previously known as morbidly) obese - BMI ≥40.0 kg/m².
What are the causes of obesity?
Calorie intake > calorie expenditure
Factors associated wiith energy imbalance:
- genetic predisposition - up to 70% but no “fat gene”
- behavioural dynamics - tend to larger portions, sedentary, poor diet, eating disorder, mental illness
- hormonal disturbance - hypothyroid, hypercortisolism, insulinoma
- cultural influence - childhood, contributes to behavioural
- environmental circumstances - low socioeconomic level, in utero nutritional environment
List some risk factors for obesity.
- Hyperthyroidism
- Hypercortisolism
- Corticosteroid therapy
- Age >40yrs
- Peri and postmenopause
- Prior pregnancy
- Married
- Sleep deprivation
- Hx of smoking
- Less formal education
- Poor in utero nutrition
- Low socioeconomic level
- Sedentary lifestyle
- TV watching and video games >3hrs a day
- Diet high in sugar, cholesterol, fat and fast food
- Heavy alcohol intake
- Night eating syndrome
- Binge eating disorder
- Leptin deficiency
- Antidepressant therapy
- Antipsychotic therapy
- Beta-blocker therapy
- Adjuvant breast cancer therapy
- Psychiatric diagnosis
What investigations would you do for obesity?
Clinical exam - height and weight
- FBC - normal or anaemia
- serum transaminases - look for liver dysfunction
- TFTs - check for hypothyroidism
- ECG - normal unless heart disease
- Polysomnography (sleep study)- may show obstructive sleep apnoea
When is BMI not accurate?
The BMI is a reasonable determination of obesity in the vast majority of people, but it is not accurate in
- pregnancy or
- in people with a large amount of muscle mass (e.g., professional athletes).
In addition, the BMI does not account for
- sex,
- age, or
- bone structure,
all of which can influence the relative amount of body fat
Apart form BMI and central adiposity, what other measure may be used to predict risk of CVD especially in those with a BMI <35kg/m2?
Waist to height ratio:
- Healthy = 0.4 to 0.49, indicating no increased health risks.
- Increased = 0.5 to 0.59, indicating increased health risks.
- High = 0.6 or more, indicating further increased health risks
How do you classify obesity in people of Asian/African background?
Overweight = BMI 23-27.4kg/m2
Obese = BMI >27.5 kg/m2
How do you measure waist circumference?
Between bottom of ribs and top of hips
Breathe out naturally before taking measurement
Waist should be kept to below half their height
What must you do before discussing a person’s weight with them?
Ask for their permission
If people are upset about the term obesity you should ensure they understand the term is a clinical term with specific health implications, rather than a question of how a person looks.
At what point can drug treatments for obesity be considered?
- BMI >28kg/m2 AND with associated risk factors (T2DM, HTN, dyslipidaemia) OR
- Dietary intervention and physical activity have been trialled OR
- BMI >35kg/m2
What are the indications for bariatric surgery?
Should fulfil all the following criteria:
- BMI of >40 kg/m2 , or between 35 kg/m2 and 40 kg/m2 with significant disease that could be improved if they lost weight
- All appropriate non-surgical measures have been tried
- The person has been receiving or will receive intensive management in a tier 3 service.
- The person is generally fit for anaesthesia and surgery.
- The person commits to the need for long-term follow up
What are the types of bariatric surgery?
Roux en Y gastric bypass
Sleeve gastrectomy
Historical/less common:
- Adjustable gastric banding
- Biliopancreatic diversion with or without duodenal switch
- Vertical banded gastroplasty
- Jejunoileal bypass
- Magenstrasse-Mill procedure
