1. Body weight and composition

2. Learning objectives What are the risks of being overweight or obese?
How do we measure body composition? What are the pros and cons of BMI and Waist-Hip ratios?
What influences weight?
Understand how energy balance influences weight.
How can our diet and dieting influence body weight?
Describe medical (drug and surgical) approaches to weight loss. What are the costs and benefits?
Understand how anorexia and bulimia can adversely affect health.

3. Body weight
What is considered a ‘healthy’ body weight?
What is BMI?

5. Underweight deaths often due to smoking and disease
Overweight deaths often due to cardiovascular disease

6. BMI Underweight: < 18.5 Healthy: 18.5 – 24.9 Overweight: 25 – 29.9
Obese: >30
Why is BMI useful?
What are problems with BMI measurements?

7. BMI risks vary by region

8. Waist to hip ratio - WHR
Visceral fat (around waist) worse than subcutaneous fat (around hips and buttocks)
BE AN PEAR, NOT AN APPLE!

9. WHO waist-to-hip ratio guidelines

10. Body fat
Men: 8-24%
Women: 21-35%

11. Global obesity epidemic

12. Obesity in the U.S.
Obesity varies by ethnic group, age, gender, and region
Huge increase since 1990

13. Health issues related to obesity
MANY, including
High blood pressure
Diabetes
High cholesterol
coronary heart disease
Stroke
Sleep apnea
Lung problems
Difficulty getting pregnant

14. Factors that influence your weight
Energy Balance
Genetics
Hormones
Age and gender
Obesogenic environments
Availability of ‘fatty’ foods
Eating out
Large portions
Sedentary lifestyle
Lack of sleep
We can control this the most!

15. Energy Balance Energy in = energy out Energy in: Energy use:
3500 calories per pound of fat
Reducing calories eaten by 3500 calories a week will result in about a pound lost per week (500 cal / day)
Energy use:
Process food (~10% of energy consumed)
Basal metabolic rate (60-70% of energy consumed)
Physical activity (10-30% of energy consumed)

16. Dieting
The best type of diet is one that you can maintain for a long time
Changes in lifestyle
Maintains a healthy, balanced diet
Emphasizes Complex carbohydrates
Having group support helpful (eg Weight Watchers)
Be wary of fad diets
Some foods are ‘good’ or ‘bad’
Or ‘fat-burning’
No scientific data support these claims

17. Very low calorie diets < 800 calories per day Rapid weight loss
Muscle loss (including of heart)
Metabolism slows even after diet

18. ‘Light’ foods
‘low fat’ foods often replace fat with sugars and salt (sodium)
Artificial sweeteners may make you gain weight
Body craves more sweet things

19. Prescription drugs Act on the brain to reduce caloric intake
reduced appetite
Act on digestive system to reduce absorption of fats
Minimally effective if your diet is already low in fat
All have side effects

20. Surgery
Major risks and side effects to both

21. Keeping weight off Control what you can in the energy balance equation
Reduce calories you eat
Increase calories you burn
Exercise!!!
Adjust your lifestyle to one that you can maintain for a long time
Set realistic goals