Energy Balance and
Weight Management
Good health, including weight management,
requires an equilibrium:
Energy intake must equal energy output
Good health, including weight management,
requires an equilibrium:
Energy intake must equal energy output
If energy intake exceeds
energy output (“positive
energy balance”) the extra
calories will be stored as
fat - you will gain weight.
Good health, including weight management,
requires an equilibrium:
Energy intake must equal energy output
If energy intake exceeds
energy output (“positive
energy balance”) the extra
calories will be stored as
fat - you will gain weight.
If energy output exceeds
energy intake (“negative
energy balance”) your
body will used stored fat
and glycogen (and, if
necessary, protein) to
produce energy you will lose weight
Energy Balance:
We’ve already discussed sources of energy intake:
Energy Balance:
We’ve also discussed some types of energy output:
Exercise:
Cellular
processes:
Heat
production:
Energy Balance:
Intake is regulated by both internal and external cues:
Internal cues: Your brain is constantly monitoring the
energy needs of your body and whether or not these
needs are being met.
This has three components:
Hunger - prompts eating
Satiation - signals to stop eating
Satiety - keeps you from starting
to eat again
Energy Balance:
Intake is regulated by both internal and external cues:
External cues: Your brain creates a desire to eat a
specific food or type of food, called appetite, which
may or may not be directly related to meeting the
energy needs of the body.
Components:
Mood
Stress
Social situations
Time of day or
Time of year
Energy Balance: Food intake
These internal and external cues work together in a
number of ways to influence food (and thus energy)
intake:
1. Chewing, salivation, and swallowing send signals to
the brain which decrease hunger and appetite
Energy Balance: Food intake
These internal and external cues work together in a
number of ways to influence food (and thus energy)
intake:
1. Chewing, salivation, and swallowing send signals to
the brain which decrease hunger and appetite
2. Stretching of the stomach (and possibly the intestine)
sends signals to the brain which decrease hunger
and appetite.
Energy Balance: Food intake
These internal and external cues work together in a
number of ways to influence food (and thus energy)
intake:
1. Chewing, salivation, and swallowing send signals to
the brain which decrease hunger and appetite
2. Stretching of the stomach (and possibly the intestine)
sends signals to the brain which decrease hunger
and appetite.
3. More than fifty different chemicals influence how the
brain processes feelings of hunger, appetite,
satiation, and satiety
Energy Balance: Food intake
(Chemicals which influence how the brain processes
feelings of hunger, appetite, satiation, and satiety)
3a. Neuropeptide Y is a protein produced in the brain
which stimulates hunger and appetite and thus
increases food intake
Energy Balance: Food intake
(Chemicals which influence how the brain processes
feelings of hunger, appetite, satiation, and satiety)
(Neuropeptide Y)
3b. Ghrelin is a hormone produced in the stomach which
stimulates hunger and appetite. It rises early in a
meal, then falls quickly after the meal is over. It also
slows down the body’s burning of fat.
Energy Balance: Food intake
(Chemicals which influence how the brain processes
feelings of hunger, appetite, satiation, and satiety)
(Neuropeptide Y; Ghrelin)
3c. Leptin is a hormone produced by fat cells which
stimulates satiety, thus decreasing food intake. It is
produced in direct proportion to the amount of stored
fat, but over time its production drops even of fat is
unchanged.
Energy Balance: Food intake
(Chemicals which influence how the brain processes
feelings of hunger, appetite, satiation, and satiety)
(Neuropeptide Y; Ghrelin; Leptin)
3d. Insulin is a hormone produced by the pancreatic
islets which stimulates satiation and satiety, thus
decreasing food intake.
Energy Balance: Food intake
(Chemicals which influence how the brain processes
feelings of hunger, appetite, satiation, and satiety)
(Neuropeptide Y; Ghrelin; Leptin; Insulin)
3e. Cholecystokinin is a hormone produced by the
small intestine which stiulates satiation and satiety,
thus decreasing food intake
Energy Balance: Food intake
These internal and external cues work together in a
number of ways to influence food (and thus energy) intake:
(1. Chewing, salivation, and swallowing)
(2. Stretching of the stomach)
(3. Chemicals)
4. The composition of your diet will also affect food intake:
Proteins promote satiety the most
Carbohydrates promote satiety moderately
Lipids promote satiety the least
Diets high in fiber promote satiety
Solids promote satiety more than liquids
Energy Balance: Food intake
These internal and external cues work together in a
number of ways to influence food (and thus energy) intake:
(1.
(2.
(3.
(4.
Chewing, salivation, and swallowing)
Stretching of the stomach)
Chemicals)
Composition of the diet)
5. The flavor, texture, color, and temperature
of food can influence appetite
Energy Balance: Food intake
These internal and external cues work together in a
number of ways to influence food (and thus energy) intake:
(1.
(2.
(3.
(4.
(5.
Chewing, salivation, and swallowing)
Stretching of the stomach)
Chemicals)
Composition of the diet)
Flavor, texture, color, temperature)
6. The smell of food has a strong effect
(either positive or negative)
on hunger and appetite
Energy Balance: Food intake
Many cultural & societal factors also influence food intake:
+
Your mom or your coach: “Eat, Eat!”
Social situations with lots of people
Large serving sizes
Advertising
Dim lighting/romance
Distraction from loneliness, anger, boredom
-
Awareness of what you are eating
Fear of gaining weight (anorexia)
Energy Balance: Food intake
Obviously, the “cues” which stimulate or inhibit hunger,
appetite, satiation, and/or satiety are very complex and
they all interact in multiple ways.
Nutritionists often talk about this as “contol by committee” –
no single factor can be identified, but working together
these factors effectively stimulate or inhibit
a) The need to eat (hunger)
b) The desire to eat (appetite)
c) The feeling of “I’m full so I’ll stop now” (satiation)
d) The feeling of “It’s not time to eat again yet” (satiety)
The other side of the energy balance equilibrium,
of course, is Energy Output.
Just as there are many ways you gain energy through food
intake, there are many ways you use energy.
Your textbook lists three
components of energy
expenditure
but
Physiologists consider
heat production to be
separate from other
types of “resting” energy
expenditures
Energy Balance: Energy Output
1. Ingesting, digesting,
absorbing, and
metabolizing the food you eat
requires a significant amount
of energy. This is called the
Thermic Effect of Food.
At rest, this is 5% to 10% of
total expenditure.
It peaks one or two hours after eating and lasts for four
to five hours.
Energy Balance: Energy Output
2. By far, the largest energy
expenditure is the Resting
Energy Expenditure (REE)
needed for the basic body
functions to stay alive
such as breathing, circulating
blood, nerve function,
moving molecules into and out of cells, maintaining body
temperature, bone and muscle growth, forming urine,
fighting infections, reproducing, etc.
At rest, this is 60% to 75% of total energy.
It is also known as the Basal Metabolic Rate (BMR)
Energy Balance: Energy Output
Resting Energy Expenditure
or Basal Metabolic Rate are
defined as the amount of
energy (kcals) used for these
functions over a full day.
When calculated per hour it is
the Resting Metabolic Rate
(RMR).
Energy Balance: Energy Output
Resting Energy Expenditure
or Basal Metabolic Rate are
defined as the amount of
energy (kcals) used for these
functions over a full day.
When calculated per hour it is
the Resting Metabolic Rate
(RMR).
Thus, if you maintained a Resting Metabolic Rate of
60 kcal/hour
then your Resting Energy Expenditure would be
(60 kcal/hour) x (24 hours) = 1,440 kcal/day
Energy Balance: Energy Output
Resting Energy Expenditure
primarily depends on the lean
body mass – the total mass of
everything that isn’t fat.
Thus, a muscular person will
have a higher RMR and REE
than a nonmuscular person.
Energy Balance: Energy Output
Resting Energy Expenditure
primarily depends on the lean
body mass – the total mass of
everything that isn’t fat.
Thus, a muscular person will
have a higher RMR and REE
than a nonmuscular person.
In general, men have more lean body mass than women,
but in both sexes the lean body mass (and thus both RMR
and REE) decline with age.
Energy Balance: Energy Output
Resting Metabolic Rate can
be estimated by multiplying
the weight in kilograms by
1 kcal/kg for men and
0.9 kcal/kg for women
and
Resting Energy Expenditure
can then be calculated by
multiplying this by 24 hours.
Energy Balance: Energy Output
However: many other factors can
change resting metabolic rate
and resting energy expenditure.
Energy Balance: Energy Output
3. The most variable energy
expenditure is the Energy
Expenditure of Physical
Activity.
For most people, this is 15%
to 30% of total expenditure,
but for extremely active
people it can be as much as
50% or 60% of total
expenditure.
Energy Balance: Energy Output
3. The most variable energy
expenditure is the Energy
Expenditure of Physical
Activity.
Muscle contraction, whether it
is used to walk around during
a normal schoolday, climb up
Sugarloaf, or run the Twin Cities
Marathon, requires a very large
amount of energy.
Energy Balance: Energy Output
Energy Expenditure of Physical Activity:
For example:
An 80 kg (175 pound) person uses approximately:
95 kcal per hour when sleeping
140 kcal per hour when reading or studying
275 kcal per hour when walking at a moderate pace
550 kcal per hour when jogging
650 kcal per hour when swimming laps
1,300 kcal per hour when running at top speed
Energy Balance: Energy Output
Energy Balance: Energy Output
While it can be useful to
separately determine the
Thermic Effect of Food, the
Resting Energy Expenditure,
and the Energy Expenditure
of Physical Activity, most
often it is more important to
know the sum of all three,
the Total Energy Expenditure (TEE)
Energy Balance:
Remember:
The total amount of energy your body expends each day
must equal the number of calories consumed in food, so
you can calculate an Estimated Energy Requirement –
the amount of energy intake needed each day to maintain
energy balance in a healthy individual of normal weight.
Total Energy
Expenditure
=
Estimated Energy
Requirements.
Energy Balance: Energy Intake
but
there are many online
calculators into which
you can enter these
values and determine your EER.
For most people, this is between 2,000 and 2,800 kcal/day
Body Composition:
Note that both your Estimated Energy Requirements
(calories consumed) and your Estimated Energy
Expenditure (calories used) are strongly influenced by
your body weight.
Body Composition:
Note that both your Estimated Energy Requirements
(calories consumed) and your Estimated Energy
Expenditure (calories used) are strongly influenced by
your body weight.
However: not all “weight” is equal.
Muscles, bones,
blood,
and solid organs are
relatively heavy
Body Composition:
Note that both your Estimated Energy Requirements
(calories consumed) and your Estimated Energy
Expenditure (calories used) are strongly influenced by
your body weight.
However: not all “weight” is equal.
Muscles, bones,
blood,
and solid organs are
relatively heavy
Fat and other
connective tissues
are relatively light
Body Composition:
The commonly accepted method for assessing your body
composition is the Body Mass Index (BMI) which is the
ratio of your weight to the square of your height.
weight (kg)
BMI =
height (m2)
or
weight (lbs)
x 704.5
2
height (in )
This correlates well with the amount of lean mass and fat
you have, and with your risks for developing a number of
diseases.
Body Composition:
Normal:
BMI between
18.5 and 24.9
Body Composition:
Underweight:
BMI below 18.5
Normal:
BMI between
18.5 and 24.9
Body Composition:
Underweight:
BMI below 18.5
Normal:
BMI between
18.5 and 24.9
Overweight:
BMI between
25 and 29.9
Body Composition:
Underweight:
BMI below 18.5
Normal:
BMI between
18.5 and 24.9
Overweight:
BMI between
25 and 29.9
Obese:
BMI above 30
Body Composition:
Excess body fat, measured as
a high Body Mass Index, is a
well established indicator of
increased risk for diseases
such as diabetes, stroke, heart
disease, and many cancers.
Body Composition:
Excess body fat, measured as
a high Body Mass Index, is a
well established indicator of
increased risk for diseases
such as diabetes, stroke, heart
disease, and many cancers.
However, BMI is just an estimate for most adults: it’s less
accurate for predicting risk in children, the elderly, highly
muscular individuals, and well-trained athletes.
In some instances, therefore, more direct measurements
of the amount of fat are necessary.
Body Composition:
(More direct measurements of fat are often necessary)
The most accurate way to measure
fat is a technique called “dual
energy X-ray absorptiometry”.
As its name implies,
this requires a specific instrument which is
not available outside of a hospital setting
and is very expensive.
Body Composition:
(More direct measurements of fat are often necessary)
Less expensive methods include
Underwater or hydrostatic weighing
Air displacement in a contained space
Both take advantage of the fact that fat
is much less dense than bone, muscle, etc.
so it displaces less water or air per kilogram
or per pound.
Body Composition:
(More direct measurements of fat are often necessary)
Less expensive methods include
Bioelectrical impedence,
which takes advantage of the fact
that fat conducts electricity much
more slowly than other tissues
Body Composition:
An analysis of skin fold thickness
on specific regions of the body
using calipers is simple and
inexpensive, and if done correctly
can accurately measure the
amount of fat
Body Composition:
While the total amount of fat is an
important risk factor for health
problems and early death, where
the fat is located is also an
important risk factor.
Body Composition:
While the total amount of fat is an
important risk factor for health
problems and early death, where
the fat is located is also an
important risk factor.
Fat deposited above the waist,
primarily in the abdomen, is called
android obesity because it is more common in men.
Body Composition:
While the total amount of fat is an
important risk factor for health
problems and early death, where
the fat is located is also an
important risk factor.
Fat deposited above the waist,
primarily in the abdomen, is called
android obesity because it is more common in men.
Fat deposited below the waist, primarily around the hips,
butt, and thighs, is called gynoid obesity because it is
more common in women.
Body Composition:
While the total amount of fat is an
important risk factor for health
problems and early death, where
the fat is located is also an
important risk factor.
Android obesity, the “apple” shape,
indicates a higher risk of disease
and death than gynoid obesity, the “pear” shape.
Body Composition:
A simple way to identify where fat is
being deposited is to measure the
waist and hips.
A waist measurement greater than
- 35 inches for women or
- 40 inches for men
is a sign of increased health risk in individuals with
body mass indices between 25 kg/m2 and 35 kg/m2
Overweight and Obesity
In fact, obesity has now become the largest contributor to
health problems and death throughout the United States and
many other countries.
- the number of adults with BMIs > 25kg/m2
in the US has increased from 48% to more
than 65% in the past 30 years.
Overweight and Obesity
In fact, obesity has now become the largest contributor to
health problems and death throughout the United States and
many other countries.
- the number of adults with BMIs > 25kg/m2
in the US has increased from 48% to more
than 65% in the past 30 years.
- one out of five (17%) of U.S. children aged
6 to 19 are overweight or obese.
Overweight and Obesity
In fact, obesity has now become the largest contributor to
health problems and death throughout the United States and
many other countries.
- the number of adults with BMIs > 25kg/m2
in the US has increased from 48% to more
than 65% in the past 30 years.
- one out of five (17%) of U.S. children aged
6 to 19 are overweight or obese.
- 300,000 deaths each year are due
to obesity among US adults.
Overweight and Obesity
In fact, obesity has now become the largest contributor to
health problems and death throughout the United States and
many other countries.
- the number of adults with BMIs > 25kg/m2
in the US has increased from 48% to more
than 65% in the past 30 years.
- one out of five (17%) of U.S. children aged
6 to 19 are overweight or obese.
- 300,000 deaths each year are due
to obesity among US adults.
- More than 90% of Type 2 diabetes
in the US is due to obesity.
Overweight and Obesity
Overweight and Obesity
Table 8.7 in your textbook lists some of the more common
“risks of being overweight”.
Be sure you are familiar with the information in this table.
It will be “fair game” on exams.
Overweight and Obesity
So: What is causing this rise in the number of overweight
(BMI > 25kg/m2 ) and obese (BMI > 25kg/m2 ) individuals?
Biological Factors: Genetics and Heredity You are
more likely to be overweight or obese
if one or both of your parents are,
particularly if they developed it
earlier in life.
Overweight and Obesity
So: What is causing this rise in the number of overweight
(BMI > 25kg/m2 ) and obese (BMI > 25kg/m2 ) individuals?
Biological Factors: Genetics and Heredity
Number and size of fat cells The more
fat cells you have, and/or the bigger they
are, the greater your risk of becoming
overweight or obese
Overweight and Obesity
So: What is causing this rise in the number of overweight
(BMI > 25kg/m2 ) and obese (BMI > 25kg/m2 ) individuals?
Biological Factors: Genetics and Heredity
Number and size of fat cells
Sex Women have somewhat higher rates
of overweight and obesity than do men
Overweight and Obesity
So: What is causing this rise in the number of overweight
(BMI > 25kg/m2 ) and obese (BMI > 25kg/m2 ) individuals?
Biological Factors: Genetics and Heredity
Number and size of fat cells
Sex
Age Throughout most of your life, your
risk of overweight and obesity increases,
then declines as you get elderly. Childhood
obesity is one of the fastest growing groups.
Overweight and Obesity
So: What is causing this rise in the number of overweight
(BMI > 25kg/m2 ) and obese (BMI > 25kg/m2 ) individuals?
Biological Factors: Genetics and Heredity
Number and size of fat cells
Sex
Age
Race and ethnicity In the US, hispanic
and black women are more likely to be
overweight or obese than white or Asian
women. Rates are similar among black,
white, and hispanic men but greater than
in Asian men.
Overweight and Obesity
So: What is causing this rise in the number of overweight
(BMI > 25kg/m2 ) and obese (BMI > 25kg/m2 ) individuals?
Biological Factors: Genetics and Heredity
Number and size of fat cells
Sex
Age
Race and ethnicity
There are obviously many social & environmental factors
as well
Overweight and Obesity
Overweight and Obesity
So: What is causing this rise in the number of overweight
(BMI > 25kg/m2 ) and obese (BMI > 25kg/m2 ) individuals?
Lifestyle and Psychological Factors:
Lack of physical activity is the greatest contributing
factor to overweight and obesity.
Only about 20% of all Americans get adequate exercise.
25% are essentially not active at all
Overweight and Obesity
So: What is causing this rise in the number of overweight
(BMI > 25kg/m2 ) and obese (BMI > 25kg/m2 ) individuals?
Lifestyle and Psychological Factors:
The desire for sexual attractiveness,
often linked with inaccurate body image,
drives both eating and exercise decisions.
Overweight and Obesity
So: What is causing this rise in the number of overweight
(BMI > 25kg/m2 ) and obese (BMI > 25kg/m2 ) individuals?
Lifestyle and Psychological Factors:
Emotional stress and depression are known to be
risk factors for overweight and obesity.
Overweight and Obesity
So: What is causing this rise in the number of overweight
(BMI > 25kg/m2 ) and obese (BMI > 25kg/m2 ) individuals?
Lifestyle and Psychological Factors:
Binge eating, bulemia nervosa, and other eating
disorders are linked to overweight and obesity.
More than 8,000,000 Americans have an eating disorder,
85% of whom are female
Weight Management:
Obviously, proper weight management is necessary for
good health, and that requires energy equilibrium:
Energy intake must equal energy output:
If energy intake exceeds
energy output (“positive
energy balance”) the extra
calories will be stored as
fat - you will gain weight.
If energy output exceeds
energy intake (“negative
energy balance your body
will used stored fat and
glycogen (and, if
necessary, protein) to
produce energy you will lose weight
Weight Management:
Weight management is the adoption of healthy and
sustainable eating and exercise behaviors indicated for
reduced disease risk and improved feelings of energy and
well-being.
Note the two components: Eating behaviors
and
Exercise behaviors
These can be difficult to develop and maintain, particularly
as we get older.
Weight Management:
- Be aware of what you eat and the number of calories
Weight Management:
- Be aware of what you eat and the number of calories
- Balance energy intake among fat (20-35% of calories)
protein (0.8g per kg body wt)
carbohydrate (45-65% of calories)
Weight Management:
- Be aware of what you eat and the number of calories
- Balance energy intake among fat (20-35% of calories)
protein (0.8g per kg body wt)
carbohydrate (45-65% of calories)
- Eat regularly (don’t skip meals)
Weight Management:
- Be aware of what you eat and the number of calories
- Balance energy intake among fat (20-35% of calories)
protein (0.8g per kg body wt)
carbohydrate (45-65% of calories)
- Eat regularly (don’t skip meals)
- Select diet behaviors that will be easy to maintain
Weight Management:
- Be aware of what you eat and the number of calories
- Balance energy intake among fat (20-35% of calories)
protein (0.8g per kg body wt)
carbohydrate (45-65% of calories)
- Eat regularly (don’t skip meals)
- Select diet behaviors that will be easy to maintain
- Stay active and/or get regular exercise
Weight Management:
- Be aware of what you eat and the number of calories
- Balance energy intake among fat (20-35% of calories)
protein (0.8g per kg body wt)
carbohydrate (45-65% of calories)
- Eat regularly (don’t skip meals)
- Select diet behaviors that will be easy to maintain
- Stay active and/or get regular exercise
- Manage your psychological health
Weight Management:
For most people, that is difficult
to do.
Effective weight management
requires being aware of the
factors which influence both diet
(energy intake) and exercise
(energy output), and then the
conscious modification of
behaviors.
Weight Management:
Many people, of course, are unwilling or
unable to make the behavioral changes
necessary for weight managment.
Weight Management:
Many people, of course, are unwilling or
unable to make the behavioral changes
necessary for weight managment.
There are hundreds of over-the counter
drugs or supplements which promise to
suppress your appetite, “burn fat”, etc.
Weight Management:
Many people, of course, are unwilling or
unable to make the behavioral changes
necessary for weight managment.
There are hundreds of over-the counter
drugs or supplements which promise to
suppress your appetite, “burn fat”, etc.
Many of these are relatively harmless
herbal supplements, but others such as
the amphetamines can be dangerous.
Weight Management:
There are some presciption drugs which
can be used to assist in weight
management:
Phentermine is an appetite suppressant
Xenical interferes with the absorption of
diglycerides and triglycerides by the
intestines.
These are almost always used in
combination with behavior modification
and exercise.
Weight Management:
There are also hundreds of diet plans
advertised or promoted through
popular literature
The Atkins Diet
The Pritikin Principle
The Zone Diet
The South Beach Diet
Ornish Diet
Jenny Craig
Nutrisystem
Weight Watchers
Weight Management:
Last resort: Surgery
Underweight:
While most health issues related to weight management are
due to overweight and obesity, calling for weight loss, you
will also encounter issues related to being underweight and
thus needing to gain weight.
- Elderly
- Children
- Illness
- Metabolic disorders
- Eating disorders
- Prolonged emotional or physical stress
- Alcoholism
Underweight:
Weight-gain strategies:
Small, frequent meals
Fluids between meals
High-calorie foods and beverages
Timers or other cues
Supplements