Influences on HungerInfluences on Hunger Hunger
Physiological response to nerve signals and chemical messengers Hypothalamus: control
center in brain Many influences!
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
Absence of hunger Satiation – signal to stop
eating Satiety – satisfaction between
meals; signal not to eat
We can override hunger/satiety signals Appetite Distraction Social pressure Emotions Stress
Sustaining Satiation and Satiety
Nutrient compositionProtein is most satiatingLow-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 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 Components of Energy Expenditure – Basal Expenditure – Basal MetabolismMetabolism
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 Components of Energy Expenditure – Basal Expenditure – Basal MetabolismMetabolism
Components of Energy Components of Energy Expenditure – Physical Expenditure – Physical ActivityActivity
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 Components of Energy Expenditure – Thermic Effect Expenditure – Thermic Effect of Foodof 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 Components of Energy Expenditure – Adaptive Expenditure – Adaptive ThermogenesisThermogenesis
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 MetabolismFat 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 & Causes of Overweight & Obesity – Genetics & Obesity – Genetics & EpigeneticsEpigenetics
Causative role of genetics? Genetic influences do seem to be involved
Genetics may determine predisposition to obesity
Epigenetics Gene expression influenced by:
Diet Physical activitySatiety and energy balance
Causes of Overweight & Causes of Overweight & Obesity – EnvironmentObesity – 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 Problems of Overweight and Obesity – Perceptions & Obesity – Perceptions & PrejudicesPrejudices
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 Problems of Overweight and Obesity – Perceptions & Obesity – Perceptions & PrejudicesPrejudices
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 Crash Diets and Weight Loss FadsFads
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
Not sustainable Wastes lean body
mass– Diminishing returns
Inadequate intake of nutrients hampers metabolism– Extremely difficult to
meet needs below 1200 kcals
Very-low-calorie diets can have serious health consequences– 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 StrategiesWeight 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 – Weight Loss Strategies – Eating PlansEating 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 – Weight Loss Strategies – Eating PlansEating 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 – Weight Loss Strategies – Eating PlansEating 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 Importance of Physical ActivityActivity
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
Physical ActivityPhysical 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 MaintenanceWeight 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
UnderweightUnderweight
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 StrategiesWeight-Gain Strategies
Key diet planning strategies Adequacy and balance
Energy-dense foods Regular meals daily Large portions Extra snacks Liquid meals (shakes)
FitnessFitness 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 Weight management Cardiovascular health Diabetes prevention or management Bone and joint health Possible reduction of cancer risk Psychological health
More Benefits of FitnessMore Benefits of Fitness 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 FitnessDeveloping 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 FitnessDeveloping 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 TrainingResistance 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
Creatine Phosphate Popular supplement (ergogenic aid) Studies show improvement in muscle
strength and power No benefit for aerobic training Possible side effects:
– 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 PAGlucose 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 & PAProtein 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 Recommended Protein Intakes for AthletesIntakes 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 Vitamins and Minerals to Support ActivitySupport 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 Fluids and Electrolytes to Support ActivitySupport 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 CHO-containing
beverages
Sports Drinks vs. WaterSports Drinks vs. Water
Sports drinks Hydration is critical to optimal
performanceWater is best for most people
Sport drinks offer the followingFluidGlucoseSodium and other electrolytesSome prefer the flavor
Dietary Strategies for Dietary Strategies for Active PeopleActive 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 MealsTiming 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