Weight Management

Overweight

weight between 10% and 20% above the desirable weight for height, or a body mass index(BMI) between 25 and 29.9.

Obesity

weight 20% or more above the desirable weight for height, or a BMI of 30 0r greater

Underweight

Weight 10% or more below the desirable weight for height, or a BMI of less than 18.5%

Problems associated with underweight?

Minimal body fat stores

•Decreased energy reserves during times of physiological stress or injury

•Menstrual irregularity

•Infertility

•Osteoporosis

Problems associated with overweight/obesity

Abdominal hernias

•Certain cancers: colon, rectal, prostate, breast, uterus, cervical, ovarian

•Complications during pregnancy

•Complications during surgical procedures

•↓ Longevity 

•↓ Quality of life

•Depression

•Type 2 Diabetes

•Fertility problems

•Gallbladder & liver disease

•Heart Disease

•↑ Blood cholesterol levels

•Hypertension

•Osteoarthritis

•Respiratory problems

BMI

• an index of a person’s weight in relation to height

• determined by dividing the weight by the square of the height

  • Compared to standards for underweight, healthy, overweight, and obese

How to calculate BMI?

BMI= weight (kg)/height (m²)

What is the BMI range for a normal (healthy person)?

18.5-24.9

what does BMI not take into account?

body fats distribution

what is the estimated disease risk based on waist circumference?

• males >40 inches

  • Females > 35 inches

what is the estimated disease risk based on waist-to-hip ratio?

• males >1.0

  • Females > 0.8

Measuring Body Fat: Hydrostatic (underwater) weighing

the less a person weighs underwater compared to the person’s out of water weight, the greater the proportion of body fat

true/false: Fat is less dense (more buoyant) than lean tissue?

true

Measuring Body Fat: Skinfold test

thickness of a fold of skin is measured using a caliper

Back of the arm (triceps) and below the shoulder (subscapular)

Measuring Body Fat: Bioelectrical impedance

measured how quickly electrical current is conducted through the body

Estimates the amount of:

• body water (total body water)

• Non fat components of the body (fat free mass)

• Degree of body fat (fat mass)

Stable weight

energy in = energy out

weight loss

energy in < energy out

weight gain

energy in > energy out

energy intake

calories from carbs, protein, fats, and alcohol

1 pound stored body fat = _____ calories?

3500

what are the 3 components of energy expidenture?

1) basal (resting) metabolic rate (BMR)

2) diet induced thermogenesis (thermal effect of food)

3) physical activity

What is the breakdown of how the body expends energy?

• thermochemistry effect of food = 5-10%

• Physical activity = 25-35%

  • Basal metabolism = 60-65%

BMR

rate body expends energy to support vital functions at rest

factors affecting BMR: increased BMR

Caffeine

•Fever

•Growth

•Height

•High thyroid hormone

•Male gender

•Muscle mass

•Smoking

•Stress

Factors affecting BMR: decreased BMR

Age

•Low thyroid hormone

•Reduced energy intake (fasting, starvation, low calorie diet)

•Sleep

Thermos effect of food

• production of heat that occurs after eating

• Contributes to a rise in metabolic rate

  • Supports ingestion, digestion, absorption, transport of food (nutrients)

    •Argument for frequent meals/ snacks to  thermic effect of food

Physical activity

Most variable part of energy expenditure equation

•Varies according to:

•Body size

•Type of activity

•Volume/intensity of activity

Most effective way to increase “energy out”

Cause of obesity?

Genetics - Ob gene and Fat cell theory

Environment

Eating behavior

Ob Gene

Ob gene: produces a hormone (leptin)

•Leptin tells the body to stop eating

•Fat stores up: ↑ leptin (↓ appetite, ↑ energy expenditure)

•Fat stores down: ↓ leptin (↑ appetite, ↓ energy expenditure)

•Overweight: ? Defective Ob gene (↓ leptin production) or unresponsive to leptin

Fat Cell Theory

Overweight child has ↑ number of fat cells

•Weight loss in adulthood only decreases SIZE of fat cells, not number of fat cells

•Fat cells have enzyme Lipoprotein Lipase (LPL) which enables cells to store body fat

•The more LPL, the more the body can pull triglycerides into fat cells for storage

Environment role in obesity

Availability of food

•Lack of opportunity for vigorous physical activity

Eating behavior and obesity

Hunger: programmed by heredity (physiological)

•Appetite: influenced by learned responses (psychological)

What happens when we overeat carbs?

the body breaks carbs down into glucose and then store it as liver and muscle glycogen stores

what happens when we overeat fat?

the body breaks it down into fatty acids and stores it as body fat stores

what happens when we overeat protein?

the body breaks it down into amino acids and stores it as fat after losing nitrogen in the urine

what happens when we fast?

the body breaks the stores down into the macromolecule monomers and uses it as energy