Weight Management: Nutrition & Physical Activity

Chapters 7 & 13

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

Energy In: Food Energy In: Food CompositionComposition

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

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 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

Weight Loss Strategies – Weight Loss Strategies – Physical ActivityPhysical Activity

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

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:

– 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