EXC SCI 1120 - unit 3 Gregory Cloutier Northeastern University

does not include sleep or heart rate from exercise prescription

intermittent fasting

• Eating pattern that cycles between periods of fasting and eating 

  • Doesn’t specify which foods you should eat but rather when you should eat them

• Very popular in the health and fitness community 

• Based on evolution practices and some people think fasting sometimes is more natural than eating 3-4 meals a day

energy restriction is hard to achieve and harder to maintain

• 25-30% adherence ONLY to low cal diets at 12 months

• 20-40% achieve > 5% weight loss at 1 year

• Only 20% of women at high risk of breast cancer maintain > 5% weight loss at 5 years with daily restricted diets

timeline of tissue breakdown

36-48 hours before significant amounts of protein (muscle) start being broken down 

• Fasting or 14+ hours force the body to burn body fat due to lowering of blood sugar or carbs

• Rapid loss of fat by fasting 14-20 hours a day (Even without ex and dietary regimes)

  • Metabolic switching from liver-derived glucose to adipose cell derived ketones 

• Progress slowly, not advised to jump straight into 24-36 hour fasts 

popular methods of intermittent fasting

• 16/8 method (leangains protocol)

  • Restricting your daily eating period to 8 hours and fast for 16 hours

  • Most popular

• Eat stop eat

  • This involves fasting for 24 hours, once or twice a week 

• 5:2 diet

  • Consume 5–600 calories on two non consecutive days of the week

  • Eat normally the other 5 days of the week

Overcompensating by eating much more during the eating periods does not help

intermittent vs daily energy restriction for 5:2 diet over 6 months

• Group 1: daily energy restriction of 25% for 7 days/weel

• Group 2: intermittent energy restriction 75% 2 days/week

Results: 

• Intermittent dieters lost 6kg fat

• Daily dieters lost 4.9 kg fat 

Intermittent diet has beneficial effects on metabolism during and after restricted days

• Better at reducing insulin on “non diet days”

• Additional 25% reduction in insulin on diet days 

Positive changes:

• Improve glucose regulation

• Increases stress resistance

• Suppresses inflammation

• Cells activate pathways that enhance intrinsic defense against oxidative stress and those that remove or repair damaged molecules 

contraindictions / practical considerations for calorie restriction

Avoid routine intermittent fasting

• Pregnant or nursing

• Diabetic patients

• Infants and children

• Suffering from eating disorders 

Many people experience:

• Hunger

• Irritability

• Reduced ability to concentrate during periods of food restriction

• These initial side effects usually disappear within 1 month

bariatric surgery

Restricts the amount of food ingested 

• Decreases appetite - early satiety

Malabsorptive - limits digestion and absorption

• Decreases the length of intestine exposed to food

  •  Reduces fat absorption to ~25%

Surgery is accompanied by behavior modification - diet and exercise

sleeve gastrectomy

resection of ~80 of the greater curvature side of the stomach

smaller tubular gastric sleeve created

causes weight loss because of:

• mechanical restriction

  • Reducing volume and stomach motility - movement of food

• hormonal modification

  • Lower production of “hunger hormone” ghrelin

gastric lap band

restrictive procedure

intra gastric balloon

deflated balloon placed in stomach. filled to decrease gastric space

left in stomach for max 6 month and typically used prior to other surgery

why measure body composition

• change in body fat weight due to a weight loss program

• athletes: best body compositon for performance

• to monitor fat and fat free weight in patients with disease

• track long term changes in body fat and fat free mass with aging

body composition

essential fat

• necessary for normal functioning of the body

  • marrow of bones, cell membranes, organs, fat rich tissues in the CNS

• 2-5% total body weight in men

• 10-13% in women

  • lower is unhealthy and can be life threatening

storage fat

• adipose tissue is called storage fat

  • located around internal organs

  • subcutaneous

fat cell growth - hypertrophy v hyperplasia

hypertrophy (increase in size)

• excess fat accumulation in existing adipocytes

hyperplasia (increase in number)

• results from recruitment of new adipocytes from precursor cells in fat tissue

BMI - a common way to classify obesity

BMI = ( weight in kg / height in m ) ^ 2

composite number used to define obesity - does not take into account lean body mass

effective screening tool - it is not diagnostic

• developed for quick/easy measurement of obesity within a population

BMI classification

underweight < 18.5

normal weight 18.5 - 24.9

overweight 25-29.9

obese is anything above but broken into 3 classes

children’s BMI

2-19 BMI is age and gender specific and tracks childhood overweight into adulthood

body composition models

2 compartments - fat mass, fat free mass

3 compartments - fat mass, fat free mass, bone (mineral) mass

4 compartments - fat mass, protein mass, water mass, bone (mineral) mass

underwater weighing

person is weighed on land and in water tank to determine body density

• archimedes principle

• lean tissue = greater density than water - will sink

• fat tissue = less dense than water - will float

therefore: a person with more body fat will weigh less underwater than a person with more lean tissue

bioelectric impedance

electric current flows through the body and the resistance is measured

more muscle means they hold more water = less resistance for current to pass through

more fat tissue = more resistance to the passage of the current

BodPod air displacement plethysmograph

utilizes displacement of air within the machine and pressure - volume relationships (Boyle’s law) to estimate BV

DXA measures

distinguishes between bone and soft tissue (muscle and fat)

skinfold thickness measurement

uses calipers to measure thickness of fat under skin

based on the direct correlation between subcutaneous fat and whole body fat

leading causes of death in the US

heart disease, cancer, stroke is all related to things we can control

same with kidney disease and hypertension (high blood pressure)

diabetes and food

carbs digested and absorbed into the intested and glucose is released into blood

pancrease - releases insulin

glucose uptake: liver, muscle, adipose tissue

diabetes

metabolic disease characterized by hyperglycemia

• more than 126mg/dl in the blood is diabetic

defects in insulin secretion (insulin deficiency), insulin action (insulin resistance) or both

hyperglycemia

high glucose concentration in blood - fasting blood sugar more than 100mg/dl

insulin

naturally occuring hormone

pancrease - b cells

diabetes 1 symptoms

central: letharygy, stupor

breath: smell of acetone

gastric: nausea, vomiting, abdominal pain

respiratory: hyperventilation

systemic: weight loss

diabetes 2 symptoms

all of those in type 1 plus blurred vision and polydipsia and polyphagia

uptake of glucose via insulin action

insulin is a protein -glucose cannot directly move from blood into the pancreas

increase levels of blood glucose makes pancreas secrete insulin → binds to a signaling receptor on a cell membrane which activates pathway → stimulates ‘glut transporters’ inside the cell which binds to cell surface → opens vesicles for glucose entry into the cell → glucose stored as glycogen

insulin action

without insulin, glucose cannot go into the cell so GLUT 4 transporters help them get into the cell

1. insulin binds to receptors

2. signal transduction cascade

3. exocytosis

4. glucose enters cell

** insulin resistance

less glucose uptake for given insulin concrentration

long term effect:

• increased insulin secreation

• b cell death

• intra abdominal fat - makes it harder for them to function

waist circumfrance is good measure for how much fat we have

physical activity / exercise and glucose uptake

limited knowledge

• insulin independent mechanism - stimulation of “glut transporters”

• hypothesized mechanisms - calcium mediated uptake

• dynamic exercise - 50 fold increase in glucose update

glucose is used for glyolidic/anaerobic

treating diabetes

reducing overweight/obesity

the treatment options are diet (lowering carbs), medications (insulin or metaphorman) , lifestyle modifications (working out more combined with dietary changes)

diabetes interventions - diet only vs diet and medication

started examining weight loss effect through diet on diabetes

effects of medications on diabetes - metaformin and exogenous insulin

for first 3 months they lost 5 kg weight

after three months half got just diet other got diet and meds

adding meds helped control blood glucose better and continued to for long term

how to prevent weight gain

active lifestyle and diet

finnish diabetes preventing study of diet and exercise

pre diabetics with insulin resistance and are overweight for 3 years

two groups - control group and intervention group

finnish diabetes study two groups

control group - oral explanation once a year about benefits of diet and exercise and weight reduction

intervention group:

1. weight loss (5% of initial weight)

2. reduced fat intake (less than 30% of total caloric intake)

3. reduced sat fat - less than 10%

4. increased fiber intake

5. moderate exercise for at least 30 min/day and more than 4hrs/wk

results of finnish diabetes preventions study

intervention group has way better outcomes and more variables they did the better the outcomes - nobody did all of them though, just 3 out of 5 as max

intervention group: did not achieve 5% weight loss but atained exercise goal and there was a big decrease in diabetes incidents

exercising: independent effect in decreasing diabetes because people did not hit the exercise goal

weight loss indept too because there was a high number of diabetic incidents with people who did lose weight

conclusion: lifestyle modifications ‘super effective’

glycemic index

how quickly a food can make your blood sugar rise

lifestyle vs medication study

USA diabetes prevention program

three groups - control, medication, lifestyle modication

control - placebo and standard recs

meds - metaformin and standard recs - increase uptake of glucose into liver from blood

lifestyle modifications -

goal: maintain a 7% weight loss from baseline weight

diet: low calorie, low fat diet

physical activity: moderate intensity for at least 150min/week

lifestyle v meds results

placebo stayed the same

metaformin dropped and then leveled off, went up a bit but went back down

lifestyle dropped and crept but still stayed the lowest

metaformin and placebo increased some physical activity but lifestyle was significantly better

incidents of diabetes went up the most for placebo, then medication, then lifstyle

best treatment for diabetes

1. lifestyle modification

2. medication

3. diet only

7 countries study provided evidence for

• Major cardiovascular risk factors are universal

• For the diet hert hypothesis

• Cardiovascular disease is preventable

• That a healthy lifestyle may promote different aspects of health 

Summary - studies in the elderly showed that a healthy diet and lifestyle also is associated with a low risk cardiovascular disease and all cause mortality. Healthy diet and sufficient physical acivity may also postpone cognitive decline and decrease risk of depression

low fat diet

energy intake of 1500kcal for women and 1800 for men

30% calories from fat, 10% from sat fat

mediterranean diet

energy intake of 1500kcal for women and 1800 for men

no more than 35% calories from fat

low carbs diet (Based on atkins)

non restricted calorie diet

restricted carbs to 120 per day

dash diet - dietary approaches to stop hypertension

emphasizes veggies, fruit and low fat dairy foods - moderate amounts of whole grains, fish, poultry and nuts

consume 2,300 mg of sodium a day

lower version is 1,500 mg of sodium a day

American heart association recommends 1,500 mg a day of sodium

musculo-skeletal system is composed of

• skeleton

• muscle

• cartilage, tendons, connective tissues

musculo-skeletal system function

ambulation, performing tasks, protecing vital organs

bones

206 bones

• strong and light

• 10-12 kg in weight - less metabolic burden (takes longer to repair though)

• bone deposition (formation of new bone) - continuous process

• bone resorption (broken down and digested by the body) - continuous process

• reservoir for calcium and phosphate (electrolytes)

calcium is important for

muscular contraction, various cellular signaling processes, blood clotting

bone w age and gender

during childhood: d > r

after 30 years: r > d

estrogen and testosterone are important for bone formation

genetics, diet, and exercise play into how you lay down bone

for women they have lower turnover than men from the start and decline more rapidly at age 50

we hit peak bone mass around age 30 then decline

osteoclasts

used for bone resorption - break it down

• we need exercise to reduce excessive breakdown

osteoblasts

bone deposition - build it up/bring it back in

• increased by physical exercise and vitamin d

bone loss

bone density: 70% of bone strength

• bone density decreases with age after 30

  • decrease in estrogen (menopause) and testosterone concentrations

osteoporosis

disease that thins and weakens the bones to the point that they become fragile and break easily - no symptoms

problems from osteoporosis

increased fracture risk

• stress fractures

• compression fracture of spine

• falls

• sneeze (ribs, spine)

lifetime osteoporotic risk for fracture

• 1 in 2 women over 50

• 1 in 4 men over 50

prevalence of osteoporosis

10 million US adults - 55% older adults

8 million women (80% of cases), 2 million men (20% of cases)

mechanisms - mechanical loading

strain exerted on the bone

to promote growth you need unique and variable strain

• unique - exceeds usual loading conditions

• variable - rate of application of different loads

site specificity

similar to muscle

• localized to site where strain is applied

• after a while there is a plateau effect

types of strain

high impact force strain and joint reaction strain

high impact force strain (gravitational)

running - causes 3-6x body weight force production

jumping - causes ~6x body weight force production

force goes through skeleton up to hip

joint reaction strain (muscle contraction)

muscle generates the force - equal to the weight lifted

force goes to bone bends and force exerted where the muscle attaches - possible a little in surrounding areas of attachment

insertions from hip to thigh is your glutes

energy in (per gram)

fat = 9 calories

carbs = 4 calories

protein = 4 calories

alcohol = 7 calories

energy expenditure: basal or resting metabolism

minimum energy expended to keep a resting, awake body alive

• 60-70% of total energy expenditure

  • includes energy needed to keep heart beating, lungs breathing, and body warm

medical hazards of obesity

pulmonary disease, nonalcoholic fatty liver disease, gall bladder disease, gynecologic abnormalities, osteoarthritis, skin, phlebitis, cancer, severe pancreatitis, coronary heart disease, cataract, stroke, idiopathic intracranial hypertension

energy expenditure: thermic effect of food

• energy used to digest, absorb, and metabolize food nutrients

• “sales tax” of total energy consumed

• 5-10% of energy expenditure

energy expenditure: physical activity

varies widely among individuals but more activity = more energy burned

energy expenditure: NEAT

non exercise activity thermogenesis

fat burning during physical activity

body prefers to use carbs as energy source

PA training encourages burning of dietary fat

• for a given activity a trained individual burns more fat than a untrained person

deconditioned individuals have a:

higher risk for premature death than conditioned individuals

“healthy obesity”

phyiscally fit obese patients have LOWER mortality rates than unfit normal weight persons

• being thin doesnt guarantee being healthy

• being fat doesnt HAVE to be unhealthy

exercise and weight loss

exercise may be most critical to help maintain weight loss and maintain muscle mass and metabolic rate

physical inactivity in children

• 63% of 5-17 y.o not active enough for optimal growth

• adolescents are less active than children 2-12 (5% to 43%)

• girls - less active than boys: 40% at 13-17 yrs

• girls - less intense physical activities

physical activity and standardized tests

kids who are physically active for 1 hour a day may perform up to 40% better on tests

common traits associated with longevity

moderation, flexibility, challenge

longevity and increase in life expectancy

• decline in infant mortalilty and infectious disease

• we are not living longer but avoiding premature deaths

• ~95% of the population will live 77-93 years

aerobic fitness and age

• aerobic fitness declines 8-10% per decade

• moderately active people can attenuate this decline only 4-5% per decade

• in trained individuals, the decline may be as small as 2% per decade

quality of life goal

not the eradiaction of aging nor the prolongation of suffering but the prolongation of normal, vital function and quality of life… vigorous and vibrant activity and a grealty shortened period of functional decline

aging

a syndrome of changes that are deleterious, progressive and universal. it implies that the passage of time necessarily results in deterioration. damage occurs to molecules, to cells and to organs

aging genetics

progeria - hutchinson gilford and werner syndrome

• causes people to develop too quickly and too slowly

environment and lifestyle influence on genetics

toxic exposure and diseases damage DNA which influences genetics. these factors determine lifespan

oxidative stress

strong theory as to why we age

results of normal metabolism. electron transport chain causes free radicals and peroxides to be produced which damages cells

human body has oxygen and water and other chemicals which simply “rusts” our bodies

effects of aging on an individual

decrease in heart’s pumping capacity, reduction in lung performance, loss in muscle mass, reduced insulin sensitivity, reduction of bone density, decline in short term memory, changes in hormonal regulation, diminished capability in immune system, balance and coordination

ageotype

biological values that predict the functional capacity of a tissue and essentially estimate its “biological age”

• immune, kidney, liver, metabolic

effects of exercise on oxidative stress

decreasing caloric intake slows aging

exercise: increases metabolic activity which increases production of free radicals

the human body has an antioxidant defense mechanism: enzymes, vitamins A and C

• exercise stimulates the body’s antioxidant defense mechanism to counter free radical production and regular exercise can maintain high levels of antioxidant activity

aerobic training in the elderly

decreased aerobic capacity due to aging… decreased mitochondria, oxygen extracability, and output of blood from the heart but exercise is still really good and protective

loss of muscle mass due to aging

biggest disadvantage during old age is this loss

• decline in functional ability mainly related to loss of muscle mass

• causes decreased potassium

  • muscle stores 60% of total potassium

  • decrease in nervous system function

    decreased strength

• decline in muscle mass is correlated to decline in strength

sacropenia

age related decrease in muscle

healthy compromising behaviors can be eliminated by___

self regulatory efforts and adopting health enhancing behaviors

behavioral pathogen

a health compromising behavior or habit

• smoking, excessive eating, inactivity, substance abuse etc

behavioral immunogen

a health enhancing behavior or habit

• exercising regularly, using sunscreen, healthy eating, etc

the older you are, the more helpful these are

what influences health behaviors

biological - genes, physiology, age, gender, fitness, weight

psychological - personality, cognitive biases, emotion/ motivation

societal - social support, SES (socio economic status)

healthy behaviors - eating well, getting physical activities, not smoking, sleeping well

individual barriers to healthy behaviors

optimistic bias - belief that they are less likely to become ill than others

• people who feel vulnerable to specific health problems are more likely to practice preventive health behaviors - invincibility fallacy

inertia - if you think… then

family barriers to healthy behaviors

health habits are often acquired from parents

• obese parents are more likely to have obese kids

family support to implement change

health system barriers to healthy behaviors

medicine focuses on treatment rather than prevention

• lots of Americans don’t have health insurance

• unrealistic or confusing recommendations

community barriers to healthy behaviors

poor access to recreational facilities, food

factors that influence behavior change

predisposing factors

• knowledge, beliefs, and attitudes based on life experiences, background

enabling factors

• skills and abilities available resources

reinforcing factors

• social support, encouragement or discouragement from those around you

models of behavior change transtheoretical model

1. precontemplation - no current intention of changing

2. contemplation - recognize a problem

3. preparation - make a plan close to taking action

4. action - begin to implement the plan

5. maintenance - action plan in place ; potential for relapses