Weight Management:
Nutrition & Physical Activity
Chapters 7 & 13
Influences on Hunger

Hunger

 Physiological response
to nerve signals and
chemical messengers
 Satiation – signal to
stop eating
 Satiety – satisfaction
between meals; signal
not to eat
 Hypothalamus: control
center in brain
 Many influences!
Absence of hunger

 Volume or pressure of
food in GI tract
 Presence of nutrients in
blood, release of
hormones in response
 Nutrients’ influence on
neurotransmitters, which
in turn influence hunger
 Liver metabolism, which is
influenced by nutrients
We can override
hunger/satiety signals





Appetite
Distraction
Social pressure
Emotions
Stress
Energy In: Food Composition
Sustaining Satiation and
Satiety

Nutrient composition
 Protein is most satiating
 Low-energy density, high-fiber foods
tend to be more satiating
 Why?
 High-fat foods – strong satiety signals
 Why?

Balance among protein, fat, carbohydrate
and fiber at each meal & snack is the
goal
Energy Out

We utilize energy from food for moving
body, fueling chemical reactions,
functioning of organs
 These functions generate heat

Thermogenesis
 Basal metabolism
 Physical activity
 Food consumption: digestion & absorption
 Adaptation
Components of Energy
Expenditure – Basal Metabolism


About two-thirds of energy expended in
a day
Metabolic activities
 All basic processes of life
 Basal metabolic rate (BMR)
 Varies greatly from one individual to the
next!
 Major influence that we can control:
amount of lean tissue
Components of Energy
Expenditure – Basal Metabolism
Components of Energy
Expenditure – Physical Activity

Voluntary movement of skeletal muscles
 Most variable component of energy
expenditure
 Amount of energy needed
 Muscle mass
 Body weight
 Activity

Amount expended depends on frequency,
intensity, and duration of activity
Components of Energy Expenditure
– Thermic Effect of Food

Digestion, absorption, and utilization on
nutrients costs energy and releases heat
 Acceleration of GI tract functioning in response to
food presence
 Oxidation or other use in body


Accounts for approximately 10% of energy
intake
Energy cost depends on macronutrient
 Lowest to highest: Fat, CHO, Protein

Diet high in fat vs. carbohydrate?
Components of Energy Expenditure
– Adaptive Thermogenesis

Adapt to dramatically changing
circumstances
 Examples: intense physical conditioning,
extreme cold, trauma, stress



Extra work done by body
Amount expended is extremely variable
Not included in energy requirement
calculations
Fat Cell Metabolism

Lipoprotein lipase (LPL) activity
 Storage of triglycerides
 Obese people vs. lean people
 Activity in varying body regions
 Men vs. women


Enzyme activity releasing and breaking
down fat: individual differences
LPL activity increases after weight loss
Causes of Overweight & Obesity
– Genetics & Epigenetics

Causative role of genetics?
 Genetic influences do seem to be involved


Genetics may determine predisposition to
obesity
Epigenetics
 Gene expression influenced by:
 Diet
 Physical activity
 Satiety and energy balance
Causes of Overweight &
Obesity – Environment

Encountered daily circumstances
 Interaction between environment and
genetics (epigenetics)

Overeating
 Present and past eating and activity
patterns influence current body weight
 Availability
 Serving sizes
 Restaurant food
Problems of Overweight and
Obesity – Perceptions & Prejudices

Most obese people do not
successfully lose weight and maintain
the loss
 Social consequences
 Jobs, school, and in social situations

Psychological problems
 Embarrassment
 Other feelings
Problems of Overweight and
Obesity – Perceptions & Prejudices
Weight Cycling
Why is it hard to lose weight?

When energy intake is low, the body
conserves energy and resists weight
loss
– Metabolism slows
– Hunger hormones, such as ghrelin,
increase
– Satiety hormones, such as leptin, decrease
– LPL activity increases

Those who use diet alone as a weight
loss strategy are not usually successful
in the long term
Crash Diets and Weight Loss Fads

Diet books and weight-loss programs
 Little success with weight loss
maintenance

Weight-loss products
 Shakes, pills

Herbal products
 Laws for dietary supplements

Other gimmicks
 Body wraps, saunas, cellulite creams
Problems with Excessive
Restriction
 Very-low-calorie

Not sustainable
 Wastes lean body
mass
– Diminishing returns

Inadequate intake of
nutrients hampers
metabolism
– Extremely difficult to
meet needs below
1200 kcals
diets can have
serious health
consequences
–
–
–
–
–
–
–
–
–
–
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Gallstones
Fatigue
Nausea
Cold intolerance
Light-headedness
Nervousness
Constipation or diarrhea
Anemia
Hair loss
Dry skin
Menstrual irregularities
Other Dietary Strategies

Low-fat
– Reduced satiety
– Tend to be high in
carbohydrate
• Potential blood sugar
peaks and valleys
• Increased insulin
release
• Promotes storage
– Low-fat does not
equal low-calorie

Low-carbohydrate
– Protein is satiating
– Ketone body
production reduces
hunger
– Food choices limited
(monotony leads to
less eating)
– Long-term effects
still unclear
Bottom line: either approach may result in weight loss, but only if
overall energy intake is less than expenditure. The ability to stay with
the dietary approach generally predicts long-term success.
Weight Loss Strategies

Successful strategies
 Small changes toward patterns of eating and
exercise that you could reasonably sustain
for life
 Moderate losses
 Significant improvement in health outcomes with
loss of 5-15% of body weight
 Reasonable goals
 Reasonable rate of weight loss: 0.5 to 2
pounds per week

Incorporation of healthy eating and
physical activity
Weight Loss Strategies –
Eating Plans

Be realistic about energy intake
 Create an energy deficit, but
 Avoid restrictive eating
 Avoid rapid weight loss – it’s not just fat
you’re losing!
 Goal: nutritional adequacy without excess
 Deficit of 500 to 1000 kcalories per day
 Greatly assisted by physical activity!!
 Breakfast frequency
 Inversely related to obesity!
Weight Loss Strategies –
Eating Plans

Nutritional adequacy
 Minimum of 1200-1500 kcalories a day

Eat small portions of energy-dense food
 Eat less calorie-dense food at each meal
 Feel satisfied, not stuffed: Hara hachi bu

Load up on foods of lower energy density
 Veggies, fruits, and lean proteins!
 High-fiber foods:
 Low in energy and high in nutrients
 Require effort to eat
 Speed of food consumption
 Price of food vs. health cost
Weight Loss Strategies –
Eating Plans

Remember water
 Assistance with
weight management

To fat or not to fat?
 Energy density vs.
satiety
 See study!

Watch for empty
kcalories
 Fat, sugar, and
alcohol

Select
carbohydrates
carefully
 Whole vs. refined
 Quality and quantity
matter
 Artificial sweeteners
 Impact on energy
intake
Importance of Physical Activity

Best approach to weight management
 Moderate physical activity plus activities of
daily life

Combination of diet and physical activity
 Lose more fat
 Retain more muscle
 Regain less weight

Reduction of abdominal fat
 Especially resistance and HIIT
 Cortisol connection
Weight Loss Strategies –
Physical Activity
Physical Activity

Body composition
 Fat decreases and lean body mass
increases
 Decreased abdominal fat, decreased
disease risk

Appetite control
 Delayed appetite
 Reduces eating in absence of hunger
 Reduces emotional/stress eating (since it
helps to manage stress)
 Another cortisol connection!
Weight Maintenance

Successful weight loss
 Plateau
 Appropriate goal at this point?
 Changing up physical activities

Sustained weight loss
 Takes more effort to prevent regain than to
prevent initial gain
 Increased lean body mass helps
Underweight


Affects no more than 5% of U.S. adults
Weight gain is a matter of health
 Individual matter


Weight gain may be difficult
Demand for energy contributes to
underweight
 Physical activity
 Growth and development
Weight-Gain Strategies

Key diet planning strategies
 Adequacy and balance

Energy-dense foods
 Regular meals daily
 Large portions
 Extra snacks
 Liquid meals (shakes)
Fitness


Depends on physical activity and
exercise (not body type!)
Regular physical activity
 Increased strength and flexibility and
ability to perform daily activities
 Additional benefits include

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Weight management
Cardiovascular health
Diabetes prevention or management
Bone and joint health
Possible reduction of cancer risk
Psychological health
More Benefits of Fitness
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Restful sleep
Optimal body composition
Resistance to infectious diseases
Lower incidence of anxiety &
depression
Lower risk for some types of
cancer
Strong circulation & lung function
Stress reduction
Cortisol reduction
Strong self image
Lower risk of dementia
How much should I do?
Highly individual
 Just 15-20 min/day starts to reduce
disease risk
 Minimum for optimal health: 2.5 hrs
moderate or 1.25 hrs vigorous activity

– Not an upper limit!
• Greater benefits can be seen by increasing
duration or intensity
– Good to spread out over the week
 Excessive sedentary activity can decrease
benefits and increase CVD, depression, waist
circumference, and other adverse effects
Developing Fitness

Minimizing risk of overuse injuries
 Be active all week
 Use proper equipment and attire
 Use proper form
 Include warm-up and cool-down activities
 Challenge your strength and endurance a
few times a week
 Mix it up!
 Pay attention to body signals
Developing Fitness

Muscle conditioning
 Fit muscles use oxygen efficiently
 Increased mitochondria and vasculature
 Reduces heart’s workload
 Burns fat longer

Balanced fitness program
 Activities you enjoy doing
 Addresses all aspects of fitness
 Strength, endurance, flexibility
 Each has specific benefits
Resistance Training

Purpose
 Build muscle mass
 Increases metabolism!
 Develop and maintain muscle strength,
muscle power, and muscle endurance



Benefits for prevention of chronic
diseases
Maximizes and maintains bone mass
Improves posture & reduces risk of back
injury
Nutrition & Physical Performance

Performance and recovery both enhanced by
optimal nutrition
– We need all essential nutrients to power
movement

3 energy systems:
– ATP-CP, anaerobic, and aerobic
– All 3 systems always active and work together

ATP-CP (creatine phosphate)
– Stores of ATP and CP only power muscles 3-15
seconds
– Muscle and liver glycogen needed to continue
contraction
Fueling Exercise by the Minute
Creatine Phosphate

Popular supplement (ergogenic aid)
 Studies show improvement in muscle
strength and power
 No benefit for aerobic training
 Possible side effects:
–
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–
–
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Weight gain (water retention)
GI symptoms: nausea, diarrhea, abdominal pain
Rash, anxiety, headache, fatigue
Not appropriate for people with kidney issues
Should be avoided in children, adolescents,
pregnant women, nursing mothers, diabetics
Anaerobic vs. Aerobic

Anaerobic activities and fatigue
– High-intensity; outstrips body’s ability to
deliver oxygen
– Anaerobic glycolysis leads to drop in pH
– Impairs glycolysis, inhibits binding of
calcium in muscle

Aerobic activities and endurance
– Lower-intensity, requires oxygen
– Oxidative metabolism of energy nutrients
– Produces much more ATP, but at slower
rate
• Uses glucose and fatty acids
Endurance

As long as ATP supply meets energy
needs, activity can continue
– Rate/intensity of activity influences energy
system used

Anaerobic exercise: CP and glycogen
rapidly depleted
– Level of training highly influences shift to
anaerobic metabolism
– Number of mitochondria and efficiency of
oxygen delivery increase with training
Glucose Use During PA

Exertion
 Liver breaks down glycogen
 Release glucose into bloodstream
 Muscles use glucose and stored glycogen
 Muscle fatigue when glycogen is depleted


Glycogen storage: limited
Intensity of activity
 Impacts how long glycogen will last

CHO post-workout restores glycogen,
spares muscle tissue
Protein Use & PA

Not a significant part of fuel mix for most
 Used in muscle building
 Synthesis suppressed during activity;
accelerates afterward
 High-quality protein consumption
 Enhances muscle protein synthesis
 What is a high-quality protein?

Protein needs are higher for
endurance and strength athletes
 Need adequate CHO, as well…why?
Recommended Protein
Intakes for Athletes





Endurance athlete: 1.2-1.4 g/kg body weight
Strength athlete: 1.6-1.7 g/kg body weight
Everyday adults: minimum of 0.8 g/kg body
weight
Max. usable amount for adults: 2.0 g/kg body
weight
Risks of excessive protein intake
– Dehydration
– Mineral losses
Vitamins and Minerals to
Support Activity

Roles in supporting activity
 Assist in releasing energy from fuels
 Transport of oxygen
 Multiple vitamins and minerals, as well as
protein, involved!

Supplements
 Vast majority do not enhance performance
of well-nourished people
Fluids and Electrolytes to
Support Activity

Fluid replacement via hydration
 Hydrate before activity
 Drink extra fluid in the days before event
 Rehydrate during and after activity

Fluids for everyday, active people
 Plain, cool water

Fluids for endurance athletes
 May benefit from mineral and CHOcontaining beverages
Sports Drinks vs. Water

Sports drinks
 Hydration is critical to optimal
performance
 Water is best for most people

Sport drinks offer the following
 Fluid
 Glucose
 Sodium and other electrolytes
 Some prefer the flavor
Dietary Strategies for Active
People

Hydrate
 Thirst is a late signal of need

Choose nutrient-dense foods
 Vitamins & minerals

Consume adequate energy
 Need all energy-yielding nutrients
 CHO, protein, and fat
 Meal frequency and balance
 Stable blood glucose means stable energy levels
 Optimal maintenance of lean tissues
Timing of Meals

30 min-1 hour pre-workout
 Protein-based snack or small meal
 Timing is individual
 Not for everyone! Depends on GI picture.

During workout
 Sip water

Post-workout
 Best time to consume CHO-rich foods
 Include protein! Balance.

Fitness goals: highly individual!
 Timing strategies vary depending on goal
 Ex: carbohydrate loading