Energy Balance and Body Composition

Dr. Dedi Ardinata, M.Kes

Energy Balance

•Energy is the ability to do work

•Food energy is measured in terms of kcal

•Energy in = energy out = energy balance

•More energy in and less energy out= weight gain

•Excessive kcal in terms of carbohydrates, proteins and fats contribute to weight gain

–Over eating leads to weight gain!

Cont.

•Glucose stored in liver and muscle glycogen

•Fatty acids stored in body fat storage

•Amino acids stored as body proteins

•Less energy in and more energy out = weight loss

•Glycogen breakdown to glucose

–Brain needs constant supply of glucose

•Body fat stores to provide energy

•Body protein stores to provide energy

–Deprived situation

Cont.

•When fasting continues after glycogen depletion:

–Breakdown of amino acids to make glucose

–Liver converts fat to ketone bodies

•Serves as an alternate source of energy to the brain

•Ketone body production helps to reduce the use of AA

•One pound of body fat = ~3500 kcal

–A deficit of 500 kcal per day should contribute to one pound weight loss per week

Cont.

•Recommended weight loss:

–Half pound to one pound weight loss per week

–Gradual weight loss versus rapid weight loss

• Severely restrictive diet may lead to:

–Loss of lean body mass

–Cause deficiency state

–Cause a cycle of Yo Yo pattern

–Eventual weight gain plus more

–Change body composition

Food Composition

•How food energy measured

•Food is measured in kcal

•Heat required to raise one Kg of water to one degree centigrade

–Carb 4 kcal per gram

–Lipids 9 kcal per gram

–Proteins 4 kcal per gram

–Alcohol 7 kcal per gram

Cont.

•Bomb calorimetry:

–Instrument that measures the heat that is given off when foods are burned, and oxygen is consumed

–Direct calorimetry measures the amount of heat generated

–Indirect calorimetry measures the amount of oxygen consumed

•Human body versus the instrument

Hunger and Appetite

•Food choices we make ; reasons to eat

•Do we eat because we are hungry or force of habit

•Hypothalamus as a control center for hunger

–Sends messages about satiety

•Hunger:

–Initiates eating; the need to eat

– physiological factors

•The stomach is empty;

Cont.

•The gastric contractions

•GI hormones initiate hunger

•No nutrients present in the small intestine

•Hunger pangs

•Body’s response to hunger adapts to changes in food intake

–Restrictive food intake; pangs of hunger; adjustment

–Over eating; stomach capacity increased

–High fat meals; GI tract adapts to increase demand

Cont.

•Appetite:

–Desire to eat; initiates eating

–Learned response triggered by senses

–Need not be hungry to eat; external and internal cues

–Sight; small and aroma; the thought and the discussion on food

•Sight of favorite dessert after a full meal!

•Passing the cafeteria

Cont.

•Satiety:

–The feeling of fullness after eating

–Signals to stop eating

•Hunger and satiety; mixed signals under stress

–Person under stress may not eat, though hungry

–Negative and positive stresses (DESSERTS)

–Depression and anxiety

•May need medical intervention

Energy Expenditure

•Thermogenesis: Body’s generation of heat

•Three main categories of thermogenesis affect body’s total energy expenditure:

–Basal metabolism (basal thermogenesis)

–Physical activity (exercise induced thermogenesis)

–Thermic effects of food (diet induced thermogenesis)

•Basal Metabolism:

–Energy required to maintain life when body is at complete rest

Cont.

•The basal metabolic rate (BMR):

–Rate of energy use for metabolism after a 12 hour fast

•No physical activity and emotional rest

•Expressed as kcal per kg of body weight per hour

•Check page 249; table 8-3; BMR from body weight

•Factors that affect BMR:

–Age decreases with age

–Height Higher in taller people

Cont.

–Body Composition higher with more lean mass

–Sex higher in males

–Growth & pregnancy increase

–Body surface area increase

–Cold and hot temp. increase

–Thyroid harmone levels increase or decrease by 50%

–Smoking and caffeine increase

–Fasting and starvation lower

–Malnutrition lower

–Fever and stress increase 7% per degree

–Sleep lowest

•Adaptive thermogenesis:

–The adjustment the body makes towards energy expenditure due to environmental changes, such as cold and hot temperatures and physiological changes, such as stress and trauma

Cont.

•Physical Activity: (exercise induced)

–Extra energy needed to provide nutrients, oxygen and to eliminate waste

–Energy required depends on:

•Muscle mass

•Intensity of physical exertion, duration and type activity

•Body weight

•Check page 248. Table: 8-2

•Thermic effect of food:

–~10% of total intake

–Greater for carb foods than high fat foods

Estimating Energy Requirements

•Factors to consider include energy spent on:

–Basal metabolism

–Physical activity

–Digestion and metabolism of foods

•Factors included in the calculation of energy:

–Age, gender and activity factor

•Simple measure:

–Men kg times 24

–Women kg times 23

Cont.

•Body weight and composition:

–Direct measure of body composition not possible

–Body weight= fat + lean tissue (including water)

•What is an ideal body weight?

–Not a goal for estimating weight status ( not realistic)

–Women: first 5 feet=100 pounds; add 5 pounds to each inch after

–Men: first 5 feet=106 pounds; add 6 pounds to each inch after

•10% allowance given for large body frame,or minus 10% for smaller frame

Cont.

•Harris-Benedict equation:

–Weight in kg and height in centimeters

–1 kg=2.2 pounds

–1 inch=2.54 cms

•Male:

•66.5+13.7 (weight)+5.0 (height)- 6.75 (age)

•Women:

•655+9.56 (weight)+1.85 (height0-4.68 (age)

Cont.

•Add activity factor to the energy calculated

–Levels of intensity and activity factor on page:250

–Depends on FITT

•Frequency

•Intensity

•Time

•Type

–Aerobic workout; cardio-vascular strength

–Anaerobic: Strength; surge of energy under short periods of time

Body Mass Index (BMI)

•BMI:

–An index of a person’s weight in relation to his height

–Calculated by dividing the weight in kg by the height in cm squared

–Preferred way of evaluating the weight status

–BMI of less than 20 underweight

–BMI 20-25 normal

–BMI 25-30 overweight

–BMI of more than 30 obese

Cont.

•Fat distribution on body an important factor

•Central obesity linked with increased risks for heart disease, stroke, diabetes, hypertension, and certain types of cancer

•Are you an apple or a pear?!

–Apple shape: upper body fat; android obesity

–Pear shape: lower body fat; gynoid obesity

•The J shaped curve explain the relationship between BMI and mortality

Healthy and Obese Body Composition

Highlight Section

•Weight loss diet: low carb and high protein diet

–Steaks without potatoes

–Meatballs without pasta

•Promise dramatic weight loss

•Use sophisticated terms to lure people

•What is the effect on the body, especially kidneys with such high protein intake

•How long a person can stop from eating the carb foods that supply the main fuel to the body

–High carb intake does not cause insulin resistance; obesity does