NUTR 303 - chapter 7 part 1

the majority of adults gain about how much weight per year from early to middle adulthood

1.1-2.2 lbs per year

Most reliable and successful weight loss comes from a

commitment to lifestyle behaviors that improve dietary and physical activity
patterns

combination of improved energy balance, increased physical activity, and
behavior modification

Energy balance

The relationship between energy intake and energy expenditure

Energy equilibrium

When calories consumed matches the amount of energy expended

Positive energy balance

Energy intake exceeds energy expenditure and results in weight gain

Positive energy balance

Energy intake is less than energy expenditure and weight loss occurs

Positive energy balance is desired during growth stages:

• pregnancy

• Infancy

• Childhood

• Adolescence

Negative energy balance is desired in adults

when body fatness exceeds healthy levels

Amount of energy in food or beverages can be estimated using

Bomb calorimeter

Thermogenesis

a metabolic process in which the body burns calories to
produce heat

The body uses energy for 3 main purposes:

• basal metabolism

• Thermic Effect of Food

• Physical activity - variable

Thermic Effect of Food

Digestion, absorption, and processing of ingested nutrients

Basal metabolism (BMR)

Minimum amount of energy expended in fasting to keep a resting, awake body alive in a warm, quiet environment

Basal metabolism accounts for

about 60 to 80% of total energy expenditure

Processes involved with basal metabolism include

beating of heart, respiration of lungs, and activity of other organs

Resting metabolism (RMR)

Used if a person is not fasted or rested

BMR and RMR are expressed as

the number of calories burned per unit of time

Average BMR and RMR for men and women

Men - 1.0 kcal/kg per hour

Women - 0.9 kcal/kg per hour

BMR peaks at

one year of age and declines until age 20.

BMR remains stable from

Ages 20 to 60

BMR declines again in

Older adulthood

Factors that increase basal metabolism

• larger muscle mass

• Male gender

• Greater muscle mass

• Body temperature

• Nervous system activity

• Higher than normal secretions of thyroid hormones

• caffeine and tobacco use

• Recent exercise

• Growth stages

LMG BNH CRG

Factors that decrease basal metabolism:

• restricted calorie intake

• Aging after age 30

• Lower than normal secretions of thyroid hormones

• Less body surface area and muscle mass

RA LTH LMS

Physical activity increases energy expenditure above basal needs by

25 - 40%

Thermic effect of food (TEF)

Energy used to digest, absorb, transport, store, and metabolize

Thermic effect of food accounts for how much of energy consumed

5 - 10%

Thermic effect of food is influenced by

Food composition and size of meals (larger meals have higher TEF)

Thermic effect of food for protein rich meals is

20 - 30%

Thermic effect of food for carbohydrate rich meals is

5 - 10%

Thermic effect of food for fat rich meals is

0 - 5%

Thermic effect of food for alcohol is

20%

Thermogenesis

Change in the BMR in response to environmental stresses

Thermogenesis is produced when

The body expends energy for non-voluntary physical activity

Energy used by the body can be measured by:

Direct calorimetry

Indirect calorimetry

Energy used can be estimated based on

• weight

• Height

• Age

• Physical activity

WHAP

Direct calorimetry

Estimates energy expenditure by measuring amount of heat released by the body

Heat release is measured by

placing a person in insulated chamber surrounded by layer of water

• Change in temperature determines amount of energy person expended

Indirect calorimetry

Involves collecting expired air

• body’s use of energy and amount of oxygen consumed and carbon dioxide produced

Estimated Energy Requirements (EERs)

• Age in years

• Physical Activity Estimate

• Weight in kilograms

• Height in meters

Physical Activity (PA) Coefficient Estimate for sedentary (no physical activity)

Men - 1.00

Women - 1.00

Physical Activity (PA) Coefficient Estimate For low activity

Men - 1.11

Women - 1.12

Physical Activity (PA) Coefficient Estimate For active

Men - 1.25

Women - 1.27

Physical Activity (PA) Coefficient Estimate For very active

Men - 1.48

Women - 1.45

Body mass index formula

Body weight in kg / height ² in meters

Underweight BMI

Less than 18.5

Healthy weight BMI

18.5 - less than 25

Desirable amounts of body fat

• Men: 8% to 24%; over 24% considered obese

• Women: 21% to 35%; over 35% considered obese

— women need more body fat for reproductive functions

Methods to measure body volume:

• underwater weighing

• Air displacement

Bioelectrical impedance

• Painless, low-energy electrical current sent through body

• A tool that can estimate total body fat in less than 5 minutes

• Greater electrical resistance equals more adipose tissue

Dual energy X-ray absorptiometry (DXA)

• Measures body fat by releasing small doses of radiation through the body to assess body fat and bone density

• Most accurate

Upper body (android) obesity is related to:

• Cardiovascular disease

• Type 2 diabetes

• Hypertension

Set-point theory

• Even when identical twins are raised apart, they show similar weight gain patterns.

• Genetically predetermined body weight or fat content that is closely regulated

Environmental factors influence weight.

• Social networks and cultural or ethnic groups

• Excessive screen time

• Emotional stress

• Meals frequently eaten away from home

• Physical activity (or lack of activity)

• Inadequate access to health care

• Learned eating behaviors

• Lack of adequate sleep

• Availability of inexpensive energy-dense foods

• Poverty

Red Flags That Weight May Not Be Healthy

• Family history of obesity or obesity-related diseases

• Upper-body (apple-shaped) android fat distribution

• Hypertension (high blood pressure)

• Hypercholesterolemia (high cholesterol)

• Hyperglycemia (high blood sugar)

FUHHH