LMCC/Obesity

Body Mass Index
$$\left(\frac{\text{weight}}{\text{height}}\right)^2$$ (ie. (kg/m)²)

Classification of weight in adults

 * waist circumference (not waist to hip ratio) can be added to increase the specificity of the BMI. Those at high risk are:
 * Men > 102 cm
 * Women > 88 cm
 * There is a U shaped relationship between BMI and mortality, with those over and underweight showing an increase in mortality

Epidemiology

 * Prevelence of obesity is > 14% (Canada)
 * There has been a doubling of childhood obesity in North America over the last 20 years

Assessment

 * Calculate BMI and waist circumference
 * Ask about comorbidities
 * Coronary artery disease
 * Hypertension
 * Smoking
 * Lipid profile
 * diabetes
 * Sleep apnea
 * Osteoarthritis
 * Gallstones
 * Assess motivation for weight loss and any surrounding support or obstacles
 * Examine past attempts and assess for efficacy
 * physical exam and investigations are based on specific patient complaints

Weight Loss
If:
 * BMI>30
 * BMI 25-29.9 or high waist circumference and 2 risk factors
 * weight loss is not to exceed 1kg/week with an initial goal of 10% loss in 6 months.

Weight Prevention

 * BMI 25-29.9 and less than 2 risk factors

Dietary Therapy

 * women: 1000-1200kcal/day
 * men: 1200-1600kcal/day
 * reduce usual intake by:
 * Obese: 500-1000kcal/day
 * Overweight: 300-500kcal/day
 * these reduction will result in a loss of 1kg/week

Temporary and/or drastic diets do not generally lead to long term weight loss. By reducing the caloric intake suddenly, the body will enter a "starvation mode" and losing fat will be more difficult.

What most people who are obese need is a "permanent" change in their eating habits. Progressive substitution of bad products with healthy products will help reduce the shock from a sudden change in their eating style. A reduction of calories about 10% (maximum 20%) of their original caloric intake should do.

Behavioural therapy

 * involve patients in goal setting
 * self monitor for dietary intake and exercise
 * reward when goals are acheived (not with food though)
 * dietary behaviour: eat slower, use smaller plates
 * modify environmental cues that prompt undesired eating

Pharmacotherapy

 * use if lifestyle changes do no work after 6 months
 * appropriate if BMI > 30 or >27 with co-morbidities/risk factors
 * sibutramine
 * appetite suppresant
 * inhibits norepinephrine and seretonin reuptake
 * side effects: increased BP, tachycardia
 * orlistat
 * reduces GI fat absorption
 * side effects: reduction in fat soluable vitamins, stool leakage diarrhea
 * ezetimibe
 * cholesterol absorption inhibitor
 * side effects:arthralgias, back pain, diarrhea

Surgery

 * for severe obesity
 * "stomach stapling", a bariatric procedure