Chapter 8 energy balance and body composition

Energy Balance and Body Composition Chapter 8... What is energy?• The capacity to do work • Energy in foods is chemical energy • The body can transform this chemical energy to mechanica

Energy Balance

and Body Composition

Chapter 8

What is energy?

• The capacity to do work

• Energy in foods is chemical energy

• The body can transform this chemical

energy to mechanical, electrical or heat energy

• Calorie used in nutrition is the Kcal

– amount of heat needed to raise the

temperature of 1000g (1 kilogram) of water 1 degree Celsius

– 1000 calories = 1 Kilocalorie or Kcal – Kcal is what is used in nutrition

Energy Balance

Energy Needs

• Energy In or Kcal intake

• Energy Out or Kcal you use to move & live

Energy Needs

• Energy balance

– Kcal intake = Kcal out or output

• Positive energy balance

• Excess of energy is store as FAT

• Dietary guidelines suggest that to lose

weight 1/2 to 2 pounds/week or 1% of body weight/week.

• Severe diets may induce loss of lean

tissue and not enough nutrients.

Energy Balance

Energy IN

• Energy in is the food we eat

• Which classes of nutrients already

discussed provide the energy we need?

• What is the amount of kcal provided per

gram of these classes of nutrients?

How do we measure Food

Composition ?

Bomb Calorimeter

Food Composition

• Bomb calorimeter

• Direct calorimetry measures the heat

energy released

• Indirect calorimetry measures the amount

of oxygen consumed and carbon dioxide expelled.

Food Intake

• What is the main reason we eat?

Food Intake

Energy Out or Expenditure

Energy Out or Expenditure

• Basal metabolic rate or BMR

• Physical activity

• Thermic effect of food

• Adaptive thermogenesis**

50-65 %

Energy Expenditure

Thermic Effect of Food

• Average 5 - 10% of total need

• Energy used to process food eaten

Basal Metabolic Rate

• The amount of energy required to maintain

body functions except activity and

digestion

Basal Metabolic Rate

• Estimating BMR

• Females 23 Kcal * kg body weight

• Males 24 Kcal * kg body weight

Basal Metabolic Rate

• Weight in lbs./2.2 = wt in Kg

• Can you estimate your BMR?

Factors that Increase Basal Metabolic Rate

Factors that Decrease Basal Metabolic Rate

Physical Activity

• If you play soccer for 1 hour and your

weight is 170 lb., which will be your energy expenditure?

Energy Balance

Body Weight,

Body Composition,

and Health

Healthy Body Weight

• Current weight standards use height and

weight data and do not take body

composition into consideration

• These may be misleading.

Healthy Body Weight

– Body Mass Index (BMI) measures relative weight for height.

• Healthy is a BMI between 18.5 & 24.9

BMI and Body Shapes

Healthy Body Weight

BMI

Distribution of Body Weights

in US Adults

BMI and Mortality

Body Fat

• Normal wt men: 13-21 % body fat

• Women: 23-31 % body fat

Body Fat

• Health problems develop:

– Body fat men:

Abdominal Fat

Central obesity

is associated with higher risk

of heart disease, stroke, diabetes, hypertension, gallstones, and some Cancers

“Apple”

and

“Pear”

Body Shapes

Body Fat

• Waist Circumference

– Practical indicator of fat distribution and

abdominal fat

• ≥ 35 is considered high risk for women.

• ≥ 40 is considered high risk for men.

Body Fat

Questions?