Exercise and Your Health
Pennington Biomedical Research Center
Division of Education
First, we’ll need to define some terms…
1.
Homeostasis: This refers to the ability or
2.
Energy Expenditure: The act or process of
3.
Thermogenesis: Generation or production of
tendency of an organism or cell to maintain
internal equilibrium by adjusting its
physiological processes. Once a weight loss
or desired weight is achieved, this is what
you want. This is what your body strives for
at all times.
using up energy. This is one component that
must be considered when striving to achieve
homeostasis.
heat, especially by physiological processes.
This is one of three components to energy
expenditure.
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First, we’ll need to define some terms…
4.
Basal Metabolism: The minimal amount of
5.
Satiety: The condition of being full or
6.
Hunger: Refers to a strong desire or “need”
energy required to maintain vital functions
in an organism at complete rest. This is
measured by the basal metabolic rate
(BMR) in a fasting individual who is resting
in a warm and comfortable environment.
gratified beyond the point of satisfaction.
Often times, we ignore this feeling or fail
to notice it when eating.
for food. It is the discomfort, weakness, or
pain caused by a prolonged lack of food. It
is not the same as appetite, or craving
foods.
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Energy Expenditure
Components
 Made up of three dominant components:
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Basal metabolism
Thermogenesis
Physical activity
 Thermogenesis includes the dietary-induced and
thermoregulatory components
 Only physical activity has a substantial element of
voluntary control.
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Energy Intake
 Energy intake, on the other hand, is
entirely voluntary, except in clinical
conditions.
 Therefore, the modifiable aspects of
the energy balance equation amount
to just two variables:
 Physical activity
 Food intake
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The Two Sides to Over Eating
Under Activity
Over Eating
Driven by the
technological
revolution
Driven by the
agricultural
revolution
Inactivity, combined with overeating appear to be the largest contributors to the
obesity epidemic. When energy intake (energy in) and physical activity (energy burned)
are at balance with one another, the body is at homeostasis. There is no weight loss,
and there is no weight gain. Weight is simply maintained where it is.
This is the ideal situation, provided the individual is at a healthy weight.
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Set Point Theory
Body homeostasis
 Previous animal experiments indicate that there is
a “set point” of body weight that is correctly
defended under most conditions.
 Studies have demonstrated that there are natural
feedback systems capable of regulating energy
homeostasis with great precision in animals.
 The same is true for humans. The body wants
there to be a balance between energy intake and
expenditure.
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Overview of Energy Balance
 When energy intake is greater than energy
expenditure, there is a net weight gain
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The Energy Balance
Energy intake > Energy expenditure = weight gain
 When energy intake is less than energy
expenditure, there is a net weight loss
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Energy intake < Energy Expenditure = weight loss
Intake
Output
 When energy intake and energy expenditure are at
equilibrium with one another, weight is maintained
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Energy intake = Energy Expenditure = weight
maintenance
To lose weight, an energy imbalance
eliciting an energy deficit is required.
This can be done through dieting, exercising,
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or a combination of both.
Calories
From Foods
Calories Used
During Physical
Activity
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Set Point Theory
Body homeostasis
 However, these feedback loops have been shown to only
function appropriately within the settings in which they
were originally developed. They have been shown to be
easily disrupted by changes in the external environment,
such as inactivity and the over consumption of energydense foods.
 In experimental animals, research shows that their ability
to regulate energy balance was impaired once their
movement was restricted and they were forced to
become physically inactive.
 In addition, when their low-fat laboratory chow was
replaced by a “cafeteria diet” with energy-dense and
highly palatable foods, extreme obesity with massive fat
deposition was the outcome.
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Set Point Theory
Body homeostasis
 Similar outcomes have been noted in experiments involving humans where normal
lean volunteers were asked to eat a diet prepared for them at the amount that they
would normally consume per meal.
 These individuals were unaware that the fat content (and hence energy density) of the
diets differed between each of the three dietary treatments.
 Energy balances were shown to be strongly influenced by the energy densities of the
diets. This was believed to be due to a physiologic failure to recognize that the energy
content of the diets differed and so, appetite or energy expenditure was not modified
accordingly.
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Imbalances
Physical Activity and Food Intake
 A survival imperative common to all mammals is:
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The ability to maintain the body’s energy reserves in the form of hepatic (liver) and
muscle glycogen, together with at least a limited supply of fat
 These energy reserves are necessary to support basic physiologic and immune
functions, and to mount fight or flight responses.
 Because of these essential needs, hunger is believed to have evolved to be a strong
physiologic drive made up by robust neuro-endocrine mechanisms, which are
protected by multiple levels of redundancy.
 The same is true for humans.
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Imbalances
Physical Activity and Food Intake
 Due to recurrent periods of food shortage and famine
throughout time, it is believed that evolutionary pressures led
to the ability for fat storage to well exceed that which is
needed for day-to-day survival in humans.
 As a result, there has never been the imperative to develop
strong satiety mechanisms.
 This imbalance between effectiveness of hunger and satiety
signals is believed to lead to an asymmetry in appetite control.
This could possibly explain why current lifestyles create such
a high level of susceptibility to obesity in most individuals.
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Imbalances
Physical Activity and Food Intake
 Because of this imbalance, many individuals have to
learn to adopt cognitive dietary restraints in place of
their natural physiologic regulatory system in order to
maintain leanness.
 With the previous evidence in mind, this provides
further support on the importance of exercise in aiding
in body weight regulation.
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Imbalances
Physical Activity and Food Intake
 Consequences of this asymmetry in appetite control
are believed to be further confounded by marketing
trends towards larger portion sizes and increased
energy density of foods, each of which opposes the
need of adapting a lower calorie intake in a
progressively more sedentary world.
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The Importance of Exercise
 There are a number of published studies indicating that
physical activity benefits stable weight maintenance,
especially after a weight loss.
 The real benefit is not particularly during the weight loss
itself, although it does contribute to the weight loss when
combined with a dietary restriction, but more so in
maintaining the weight loss once it is achieved.
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The Importance of Exercise
 The importance of exercise in aiding in weight
maintenance is due to reasons discussed previously
with respect to the asymmetry in appetite control, but
is also due to the physiological effects of exercise in
enhancing well-being and status of control, and hence
compliance with a restrictive dietary regime.
 It is important to remember that there are many
additional benefits of exercise. The benefits of exercise
are not limited to just those previously discussed.
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The Importance of Exercise
It is beneficial in that it:
 Reduces your risk of heart disease, high blood
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pressure, osteoporosis, diabetes, and obesity
Reduces both total blood cholesterol and
triglycerides and increases high-density
lipoproteins, known as the “good” cholesterol.
Reduces your risk for having a second heart attack
Reduces your risk of developing colon cancer.
Contributes to mental well-being and helps to
treat depression
Helps relieve stress and anxiety
Increases your energy and endurance
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The Importance of Exercise
It is beneficial in that it:
 Helps you maintain a normal weight by
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increasing your metabolism.
(the rate in which your burn calories)
Helps you sleep better.
Keeps joints, tendons, and ligaments flexible so
it’s easier to move around.
Reduces some of the effects of aging.
Helps older adults become stronger and better
able to move about without falling or becoming
excessively fatigued.
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Physical Activity &Coronary Heart Disease
 A major, underlying risk factor for coronary heart
disease is inactivity.
 In a study published in JAMA, men, who were initially
unfit and became fit, were found to have a 52%
lower age-adjusted risk of cardiovascular disease
mortality than their peers who remained unfit.
 Regular physical activity has been shown to impact
blood pressure beneficially.
 One study found that for every 26.3 men who walked
more than 20 minutes to work, one case of
hypertension would be prevented.
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Physical Activity &Coronary Heart Disease
 It is important to note that these acute effects of exercise
on blood pressure lowering do not require vigorous
efforts. They can be achieved at 40% of maximal capacity
during exercise.
 Blood lipids play a major role in the development of
atherosclerosis, which is the underlying cause of
coronary heart disease.
 Moderate to vigorous-intensity aerobic exercise training
has been shown to improve the blood lipid profiles of
individuals.
 The most commonly observed changes have been:
increases in High density lipoprotein cholesterol (HDL),
with reductions in total blood cholesterol, low-density
lipoprotein cholesterol (LDL), and triglycerides.
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Physical Activity and Type 2 Diabetes
 Physical activity is associated with:
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A reduced risk of type 2 diabetes
Improved insulin sensitivity
Glucose homeostasis
 From participating in physical activity 30
minutes/day, overweight subjects were able to
reduce their risk of getting type 2 diabetes by
58% in a recent study.
 Physical inactivity has been shown to elevate the
risk of developing type 2 diabetes in normalweight individuals as well.
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Physical Activity & Overweight/Obesity
 Physical activity appears to be an important
component in weight stability for healthy individuals.
 In a recent study looking at the effects of physical
activity on body composition in 3,853 healthy
subjects between the ages of 15 and 64, it was
concluded that physical activity is able to limit both
fat mass and weight gain in men and women.
 Many studies are in agreement with one another
when stating that exercise + diet lead to greater
weight losses than just diet-alone.
 In a review of 11 studies looking at the influence of
both exercise and diet on weight loss, the average
weight loss of the diet-only group was shown to be
6.7 kg; whereas, the average weight loss of the diet
+ exercise group was 8.5 kg.
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Physical Activity & Overweight/Obesity
 Weight loss is not only achieved, but is
also maintained through physical activity.
 In 2001, a study was conducted on 3000
previously obese subjects, who reported a
weight loss of 30 kg, on average, which
was additionally maintained for an
average of 5.5 years.
 When looking at those who did not
continue to participate in physical activity,
it was found that only 9% of these
participants were able to maintain their
weight loss in the absence of physical
activity.
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This further supports the
importance of exercise in the
prevention of weight regain.
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Physical Activity & Overweight/Obesity
 The optimal amount of weekly exercise necessary to
prevent weight gain is still a topic under much debate.
 The current recommendations include, at a minimum,
150 minutes/wk of moderate-intensity exercise, or 30
minutes a day on most days of the week (5 or more).
 This should be the initial targeted amount of exercise
each week
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Physical Activity and Appetite Control
 Physical activity has the potential to adjust appetite control by:
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Improving the sensitivity of the physiological satiety signaling system
Adjusting macronutrient preferences or food choices
Altering the hedonic (pleasurable) response to food
 There exists a belief that physical activity drives up hunger and
increases food intake, thereby rendering it useless as a means of
weight control.
 In a recent study, researchers set out to examine this very idea.
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Physical Activity and Appetite Control
Recent Findings
 Short term (1-2 day) and medium term (7-16 day) studies demonstrated that men and
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women can tolerate substantial negative energy balances when performing physical
activity programs.
The immediate effect of taking up exercise is weight loss.
This isn't always easy to assess; however, due to changes in body composition or fluid
compartmentalization that arise.
Once around 30% of energy is expended in activity, food intake then begins to
increase in order to provide compensation for this loss.
This compensation (up to 16 days) is partial and incomplete.
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Physical Activity and Appetite Control
Recent Findings
 Subjects have been separated into compensator and non-compensator groups.
 The exact nature of the differences noted in these 2 groups has yet to be determined.
 Some subjects performing a set routine of activities for a 14 day period showed no
differences in energy intake.
 More studies are needed to further classify individuals who are compensators versus
non-compensators and to identify the mechanisms responsible for the rates of
compensation and its limits.
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Physical Activity and Osteopenia
 Everyday physical activity has a positive
effect on skeletal mass.
 It has been suggested that electrical
currents are developed when bone is
mechanically stressed, leading to the
formation of new bone.
 When comparing whole body, leg, and
trunk body mineral densities in women
who walk 7.5 miles/week versus those
who walk 1 mile per week or less,
women in the group with the most
distance were shown to have significant
increases in bone density.
Normal bone
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Osteoporotic bone
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Physical Activity and Sarcopenia
 Sarcopenia can be defined as the age-
related loss of muscle mass, strength, and
function.
 Physically active subjects aged over 65
years have a significantly higher level of
lean tissue mass than sedentary
participants.
 It has also been shown that healthy older
people can safely tolerate higher intensity
strength training with improvements
comparable with those seen in younger
persons.
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Physical Activity & Psychological Disorders
 Physical activity is associated with elevations in mood states
and heightened psychological well-being.
 On the other hand, inactive persons have been shown to be 1.5
times more likely to become depressed than those who
maintain an active lifestyle.
 Physical activity is believed to be protective against the
development of Alzheimer’s disease.
 This is believed to be due to increased blood flow, which may in
turn promote nerve cell growth.
 It has been suggested that people who are intellectually and
physically inactive have a 250% better risk of developing the
disease.
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The Truth on Exercise
 The bad news is that people still
are not getting enough exercise.
 This map specifically looks at
physical activity trends in women
and finds that only 4 in 10 women
are engaging in the recommended
levels of activity.
 Activity has been shown to
generally decrease with age, and is
less common among women than
in men and among those with lower
income and less education.
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Source: CDC. Behavioral Risk Factor Surveillance System, 2001.
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Photo from: http://womenshealth.gov
Inactivity
 Inactivity leads to a loss of muscle, to obesity, and to
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reduced functional ability.
Low physical fitness increases the risk for
cardiovascular disease, diabetes, and some cancers.
Individuals who are physically fit can do more things,
have better endurance for activities and tasks, and
are healthier than individuals with low fitness.
Even small increases in physical activity can make a
big difference to an individual’s health.
Try to incorporate small changes into your daily
activities. This, in time, will gradually improve your
fitness, leading to a better you.
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Physical Activity and Physical Fitness
What’s the difference?
 Physical activity is defined as any bodily
movement produced by skeletal muscles
that results in an expenditure of energy.
 Exercise is defined as a subset of
physical activity that is planned,
structured, repetitive, and purposeful.
 Physical fitness is a measure of one’s
ability to perform physical activities that
require endurance, strength, or
flexibility, and is determined by a
combination of regular activity and
genetically inherited ability.

Simply put, fitness is good, but physical
activity is a must!
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Types of Exercise
Aerobic, anaerobic, and resistance
 Aerobic exercise is exercise that involves
Anaerobic
large muscle groups (arms and legs) in
dynamic activities that result in substantial
increases in heart rate and energy
expenditure.
Aerobic
 Anaerobic exercise is exercise done at very
high intensities such that a large portion of
the energy is provided by glycolysis and
stored phosphocreatine. These activities
build and tone muscles, but are not as
beneficial to the heart and lungs as aerobic
activities are.
 Resistance exercise is exercise designed
specifically to increase muscular strength,
power, and endurance by varying the
resistance, the number of time the
resistance is moved in a single group (set) of
exercise, the number of sets done, and the
rest interval provided between sets.
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Resistance
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Examples
Aerobic
Anaerobic
Brisk walking
Dancing
Jogging
Bicycling
Skating
Swimming
Snow shoveling
Lawn mowing
Leaf raking
Vacuuming
Baseball
Sprinting
Tennis
Weightlifting
Leg lifts
Arm circles
Curl-ups
Dusting
Doing laundry
Washing windows
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Physical Activity for Everyone
 Everyone can benefit in some way by regular physical activity. Whether you are trying
to maintain a weight loss or just feel more energetic when you incorporate exercise into
your daily activities. There are also the benefits later in life from exercising. These
include reductions in the risk of developing chronic diseases and overall improvements
in your quality of life.
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Who Benefits and How?

Older adults:
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Parents and children:
No one is too old to enjoy the
benefits from regular physical activity.
Evidence indicates that muscle-strengthening
exercises can work to reduce the risk of
falling and fracturing bones, and can improve
the ability to live independently.
Parents can help their
children maintain a physically active lifestyle
by providing them with encouragement and
opportunities for exercise. Outings and
family events are encouraged, particularly
when everyone in the family is involved.
Centers for Disease Control
and Prevention (CDC)
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Who Benefits and How?
 Teenagers: Regular physical activity improves
strength, builds lean muscle, and decreases
body fat. Activity can build stronger bones to
last a lifetime.
 People trying to manage their weight:
Regular physical activity helps to burn
calories while preserving lean muscle mass.
Regular physical activity is an important
component to any weight-loss or weightmaintenance activity.
 People with high blood pressure:
Regular physical activity helps to lower blood
pressure.
Centers for Disease Control
and Prevention (CDC)
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Who Benefits and How?
 People with physical disabilities, including arthritis:
Regular physical activity for individuals with
chronic, disabling conditions is important because
it can help improve their stamina and muscle
strength. It can also improve the quality of life
by improving the individual’s ability to perform
daily activities.
 Everyone under stress, including persons
experiencing anxiety or depression:
Regular physical activity has been shown to
improve one’s mood, help relieve depression, and
increase feelings of well-being.
Centers for Disease Control
and Prevention (CDC)
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Getting Started
 You will first want to begin by speaking with your doctor.
 This is particularly important if you:
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Are elderly
Currently smoke
Have any health problems
Are overweight or obese
Have not been active in a while
Are currently pregnant
Are unsure of your health status
Feel pain in your chest, joints or muscles during activity
 When it is okay to begin, you want to start out slowly. A good suggestion could be to
begin with a 10-minute period of light exercise or a brisk walk every day. You can then
gradually increase how hard you exercise for and how long.
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Ways to Improve Your Health
 Walking or jogging
 Swimming
 Bicycle riding
 Group exercises
 Weight-bearing exercise, such as weight lifting,
resistance bands, or activities involving the
whole body
 Stretching, such as yoga or tai chi exercises
 Participation in active sports, such as tennis,
basketball, and soccer
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Ways to Add Activity to Your Day
 Park the car in the furthest spot from the entrance and walk the extra distance
 Get off of the bus one stop before your destination and walk
 Take the stairs instead of the elevator
 Take walking breaks during the work day
 Take a 10-minute walk during your lunch break
 Walk a dog or play outside with the kids
 Dance to your favorite music
 Use housecleaning as an exercise opportunity
 Ask a friend, family member, or coworker to walk with you
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Physical Activity Calorie Use Chart
Activity
100 lb
150 lb
200 lb
Bicycling, 6 mph
160
240
312
Bicycling, 12 mph
270
410
534
Jogging, 7 mph
610
920
1230
Jumping rope
500
750
1000
Running, 5.5 mph
440
660
962
Running, 10 mph
850
1280
1664
Swimming, 25 yds/min
185
275
358
Swimming, 50 yds/min
325
500
650
Tennis singles
265
400
535
Walking, 2 mph
160
240
312
Walking, 3 mph
210
320
416
Walking, 4.5 mph
295
440
572
The chart shows the
approximate calories
spent per hour by a
100, 150 and 200 pound
person doing a
particular activity
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Adults should strive to meet either of the following
physical activity recommendations…
 Adults should engage in moderate-intensity physical
activities for at least 30 minutes on 5 or more days of
the week (CDC/American College of Sports Medicine).
This 30 minutes per day can be accumulated in bouts
of 10 minutes throughout the day.
 Adults should engage in vigorous-intensity physical
activity 3 or more days per week for 20 or more
minutes per occasion (Healthy People 2010)
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Tip:
While activity at a higher
intensity or performed
longer does offer more
health benefits, this level of
activity may not be a
realistic goal for everyone,
at least not to start with.
Again, work your way to
this, slowly,
by setting realistic goals for
each week.
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Moderate Intensity Activity
What’s is it?
 This is an activity which generally causes a slight, but
noticeable increase in breathing and heart rate. It may also
cause light sweating.
 Some examples of moderate intensity activity include:
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Brisk walking
Swimming
Cycling
Dancing
Doubles Tennis
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Sites
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Exercise: A Healthy Habit to Start and Keep. Available at:
http://www.familydoctor.org
Exercise: When to check with your doctor first. Available at:
http://www.mayoclinic.com/print/exercise/SM00059/METHOD=print
Physical Activity. Available at:
http://womenshealth.gov/pub/steps/Physical%20Activity.htm
Physical Activity Calorie Use Chart. Available at:
http://www.americanheart.org/presenter.jhtml?identifier=756
The Journal of the American Medical Association (JAMA). Available at:
http://www.jama.com
Physical Activity for Everyone: The Importance of Physical activity. Available at:
http://www.cdc.gov/nccdphp/dnpa/physical/importance/index.htm
General Physical Activities Defined By Level of Intensity. Available at:
http://www.cdc.gov/nccdphp/dnpa/physical/pdf/PA_Intensity_table_2_1.pdf
Sarcopenia: The Mystery of Muscle Loss. Available at:
http://www.unm.edu/~lkravitz/Article%20folder/sarcopenia.html
Physical Activity and Weight Control. Available at:
http://win.niddk.nih.gov/publications/physical.htm
Aerobic or Anaerobic? Quick Activity. Available at:
http://www.americanheart.org/presenter.jhtml?identifier=3003065
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Sites
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Melzer K, Kayser B, Pichard C. Physical activity: the health benefits outweigh the risks.
Current Opinion in Clinical Nutrition and Metabolic Care. 2004; 7: 641-47.
Prentice A, Jebb S. Energy intake/physical activity interactions in the homeostasis of
body weight regulation. Nutrition Reviews. 2004; 62(7): S98-S104.
Blundell JE, Stubbs RJ, Hughes DA, Whybrow S, King NA. Cross talk between physical
activity and appetite control: does physical activity stimulate appetite? Proceedings of
the Nutrition Society. 2003; 62: 651-661.
Moore M. Interactions between physical activity and diet in the regulation of body
weight. Proceedings of the Nutrition Society. 2000; 59: 193-198.
Jakicic J, Otto A. Physical activity considerations for the treatment and prevention of
obesity. Am J Clin Nutr. 2005; 32(suppl): 226S-9S.
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About Our Company…
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The Pennington Biomedical Research Center is a world-renowned nutrition research center.
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Mission:
To promote healthier lives through research and education in nutrition and preventive medicine.
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The Pennington Center has several research areas, including:
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Clinical Obesity Research
Experimental Obesity
Functional Foods
Health and Performance Enhancement
Nutrition and Chronic Diseases
Nutrition and the Brain
Dementia, Alzheimer’s and healthy aging
Diet, exercise, weight loss and weight loss maintenance
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The research fostered in these areas can have a profound impact on healthy living and on the prevention of common
chronic diseases, such as heart disease, cancer, diabetes, hypertension and osteoporosis.
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The Division of Education provides education and information to the scientific community and the public about research
findings, training programs and research areas, and coordinates educational events for the public on various health
issues.
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We invite people of all ages and backgrounds to participate in the exciting research studies being conducted at the
Pennington Center in Baton Rouge, Louisiana. If you would like to take part, visit the clinical trials web page at
www.pbrc.edu or call (225) 763-3000.
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