Chapter 9: Energy Balance and Weight Control

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Energy Balance

"State in which energy intake, in the form of food and /or alcohol, matches the energy expended, primarily through basal metabolism and physical activity"

Positive energy balance

Energy intake > energy expended

Results in weight gain

Negative energy balance

Energy intake < energy expended

Results in weight loss

Basal metabolism (or basal metabolic rate, BMR)

The minimum energy expended to keep a resting, awake body alive

~60-70% of the total energy needs

Includes energy needed for maintaining a heartbeat, respiration, body temperature

Amount of energy needed varies between individuals

Influences on basal metabolism

Body surface area (weight, height)

Gender

Body temperature

Thyroid hormone

Age

Kcal intake

Pregnancy

Use of caffeine and tobacco

Physical activity

Increases energy expenditure beyond BMR (25-40%)

Varies widely among individuals

More activity, more energy burned

Lack of activity is the major cause of obesity

Thermic effect of food (TEF)

Energy used to digest, absorb, and metabolize food nutrients

"Sales tax" of total energy consumed

~5-10% above the total energy consumed

TEF is higher for CHO and protein than fat

Adaptive thermogenesis

Energy used to produce heat in response to overfeeding or a cold environment

Overfeeding did not cause an expected weight gain

Energy in the form of heat was produced without work done

Accounts for only ~7% of energy use

Measurement of body’s energy needs

Direct calorimetry

Measures heat output from the body using an insulated chamber

Expensive and complex

Indirect calorimetry

Measures the amount of oxygen a person uses

A relationship exists between the body’s use of energy and oxygen

What is a healthy body weight?

Based on how you feel, weight history, fat distribution, family history of obesity-related disease, current health status, and lifestyle

Current height/weight standards only provide guides

Body Mass Index (BMI)

The preferred weight-for-height standard

Estimation of body fat

Underwater weighing

Most accurate

Fat is less dense than lean tissue

Bioelectrical impedance

Low-energy current to the body that measures the resistance of electrical flow

Fat is resistant to electrical flow; the more the resistance, the more body fat you have

Infrared light

Assess the interaction of fat and protein in the arm muscle

Body fat distribution

Upper-body (android) obesity--"Apple shape"

Associated with more heart disease, HTN, Type II Diabetes

Abdominal fat is released right into the liver

Fat affects liver’s ability to clear insulin and lipoprotein

Encouraged by testosterone and excessive alcohol intake

Defined as waist to hip ratio of >1.0 in men and >0.8 in women

Body fat distribution

Lower-body (gynecoid) obesity--"Pear shape"

Encouraged by estrogen and progesterone

After menopause, upper-body obesity appears

Less health risk than upper-body obesity

Overweight and obesity

Overweight is > 10% above healthy weight

Mild obesity is 20%-40% above healthy weight

Moderate obesity is 41%-99% above healthy weight

Morbid obesity is >100% above healthy weight

Increases health risk by 12-fold

Juvenile-onset obesity

Develops in infancy or childhood

Increase in the number of adipose cells

Adipose cells have long life span and need to store fat

Makes it difficult to loose the fat (weight loss)

Adult-onset obesity

Develops in adulthood

Fewer (number of) adipose cells

These adipose cells are larger (stores excess amount of fat)

If weight gain continues, the number of adipose cells can increase

Causes of obesity

Nature debate

Identical twins raised apart have similar weights

Genetics account for ~50% of weight differences

Genes affect metabolic rate, fuel use, brain chemistry

Thrifty metabolism gene allows for more fat storage to protect against famine

Causes of obesity

Nurture debate

Environmental factors influence weight

Learned eating habits

Activity factor (or lack of)

Poverty and obesity

Female obesity is rooted in childhood obesity

Male obesity appears after age 30

Nature and nurture

Obesity is nurture allowing nature to express itself

Location of fat is influenced by genetics

A child with no obese parents has a 10% chance of becoming obese

A child with 1 obese parent has a 40% chance

A child with 2 obese parents has a 80% chance

Nature Vs. nurture

Those at risk for obesity will face a lifelong struggle with weight

Gene does not control destiny

Increased physical activity, moderate intake can promote healthy weight

Why diets don’t work

Obesity is a chronic disease

Treatment requires long-term lifestyle changes

Body defends itself against weight loss

Dieters are misdirected

More concerned about weight loss than healthy lifestyle

Unrealistic weight expectations

Why diets don’t work

Weight cycling (yo-yo dieting)

Typically weight loss is not maintained

Weight lost consists of fat and lean tissue

Weight gained after weight loss is primarily adipose tissue

Weight gained is usually more than weight lost

Associated with upper body fat deposition

Why diets don’t work

Weight gain in adulthood

Weight gain is common from ages 25-44

BMR decreases with age

Inactive lifestyle

Changes in body composition

Fluid is usually the first weight lost

Loss in lean body tissue means lowering the BMR

Very little fat is lost during weight loss

Lifestyle Vs. weight loss

Prevention of obesity is easier than curing

Balance energy in(take) with energy out(put)

Focus on improving food habits

Focus on increase physical activities

What it takes to lose a pound

Body fat contains 3500 kcal per pound

Fat storage (body fat plus supporting lean tissues) contains 2700 kcal per pound

Must have an energy deficit of 2700-3500 kcal to lose a pound per week

Do the math for weight loss

Sound weight loss program

Meet nutritional needs, except for kcal

Slow & steady weight loss

Adapted to individuals’ habits and tastes

Contain enough kcal to minimize hunger and fatigue

Contains common foods

Fit into any social situation

Chang eating problems/habits

Improve overall health

See a physician before starting

Cutting back

Control calorie intake by being aware of kcal and fat content of foods

"Fat Free" does not mean "Calories Free" (or "All You Can Eat")

Read food labels

Estimate kcal using the exchange system

Keep a food diary

Behavior modification

Modify problem (eating) behaviors

Chain-breaking

Stimulus control

Cognitive restructuring

Contingency management

Self-monitoring

Behavior Modification

Chain-breaking

Breaking the link between two behaviors

These links can lead to excessive intake

Example: Snacking while watching T.V.

Behavior Modification

Stimulus Control

Alternating the environment to minimize the stimuli for eating

Puts you in charge of temptations

Cognitive Restructuring

Changing your frame of mind regarding eating

Replace eating due to stress with "walking"

Behavior Modification

Contigency management

Forming a plan of action in response to a situation

Rehearse in advance responses to pressure of eating at parties

Self-monitoring

Helps you understand your eating habits

Weight maintenance

Prevent relapse

Occasional lapse is fine, but take charge immediately

Continue to practice newly learned behavior

Requires "motivation, movement, and monitoring"

Have social support

Encouragement from friends/ family/ professionals

Dieting can be hazardous to your health

Weight regained consists of a higher percentage of body fat than before

Less healthy than before dieting

Weight loss diet should not be considered unless you are committed and motivated

Diet drugs

Amphetamine (Phenteramine)

Prolongs the activity of epinephrine and norepinephrine in the brain

Decreases appetite

Sibutramine (Meridia)

Enhances norepinephrine and serotonin activity

Decreases appetite

Diet drugs

Fenfluramine and dexfenfluramine (Redux)

Increases serotonin released in the brain

FDA pulled it from the market

Caused pulmonary and heart valve related problems/death

Inhibits fat digestion (Orlistat)

Reduces absorption of fat in the small intestine

Only 30% effective

Homeopathic drug

Ephedrine (ma huang)

Linked to illnesses and death

Associated with nervous and cardiovascular disorder

St. John’s Wort

Antidepressant

Both taking together

Not recommended until careful testing is done

Over-the-counter diet aids

Phenylpropanolamine

Epinephrine-like drug

Cause a slight decrease in food intake

Fiber

"Filler" leading to satiety

Causes stomach distention

Benzocaine

Numbs the tongue and taste buds

Gastroplasty - stomach stapling

Common surgical procedure for treating severe obesity

Reduces the stomach size (from 4 cups) to shot glass size (2 oz)

Overeating will result in rapid vomiting

Smaller stomach promotes satiety earlier

75% will lose ~50% of excess body weight

Costly

Very low-calorie diets (VLCD)

Recommended for people >30% above their healthy weight

400-800 kcal per day

Low carbohydrates and high protein

Causes ketosis

Lose ~3-4 pounds a week

Requires careful physician monitoring

Health risks includes cardiac problems and gallstones

Underweight is also a problem

15-25% below healthy weight or BMI of <19

Associated with increased deaths, menstrual dysfunction, pregnancy complications, slow recovery from illness/surgery

Causes are the same as for obesity but in the opposite route

Treatment for underweight

Intake of energy-dense foods (energy input)

Encourage meals and snacks & Reduce activity (energy output)

To gain a pound you need a total excess intake of 2700-3500 kcal