BPK 110 Modules 11, 12 & 13

Energy definition

• Ability to do work

Energy Intake definition

• Total energy consumed from food

Energy expenditure definition

• Energy used to fuel basal metabolism, physical activity, processing food

Energy balance definition

• When energy intake = energy expenditure

Energy Intake

• Carbohydrates, lipids, protein = the three energy yielding nutrients

• Alcohol (7 kcal/g) also provides energy, but not a nutrient

• Cellular respiration breaks these bonds, releasing energy that can be captured in the bonds of ATP, body’s energy currency

• Compared to the other nutrients, more energy is required to process protein

Energy Expenditure

• We burn energy for three main purposes:

  • Basal metabolic rate (~60-75%)

  • Diet-induced thermogenesis (~10%)

  • Physical activity (~15-30%)

Basal Metabolic Rate (BMR)

• The amount of energy the body needs to perform its most basic, life-sustaining functions over a period of time

  • Ex: breathing, heart beat, nerve signalling

• When we say someone has a fast metabolism, we typically mean that they burn a lot of calories to sustain their body, even before physical activity is factored in

  • They may therefore be less likely to gain fat mass

Factors that Determine BMR

• Main controllable factor = lean body mass

• Higher BMR: certain genetic factors, male, younger age, taller height, higher lean body mass

• Lower BMR: certain genetic factors, female, older age, shorter height, lower lean body mass

Diet-Induced Thermogenesis

• AKA specific dynamic action, thermic effect of food

• Energy that is used and dissipated as heat following food intake

• More energy is required to process protein compared to other nutrients

  • However, at most, DIT accounts for 15% of energy expenditure

Physical Activity

• Voluntarily movements of the body that burns energy

• It is the portion of energy expenditure that is most under our control

  • All daily movements contribute to it

Weight Gain

• Occurs due to an increase in:

  • Fat mass

    • i.e. Due to consistent energy surplus

  • Lean mass

    • ex. Increased muscle weight

  • Water mass

    • Can fluctuate from day to day

  • Glycogen storage

    • Max = 1-2 kg of weight

Energy Retrieval

• An energy deficit occurs when energy intake is less than energy expenditure

• When a consistent energy deficit is maintained, lipids are removed from adipocytes, decreasing fat mass and weight

• If the diet is inadequate to meet current energy requirements, it turns to its energy reserves. Glycogen will be turned into glucose and body proteins will be used for their amino acids, both of which can be metabolized to form ATP

Weight Loss

• Occurs due to a decrease in:

  • Fat mass

    • i.e. Due to consistent energy deficit

  • Lean mass

    • ex. Decreased muscle weight due to proteins being broken down for energy

    • Decreases with age

  • Water mass

    • Can fluctuate from day to day

  • Glycogen storage

    • Max = 1-2 kg of weight

• For every 10 kg of metabolized fat, 1.6 kg are lost as water and 8.4 kg are lost as CO2

Energy Storage

• When energy intake is higher than energy expenditure, excess energy is mainly stored as lipid within our adipocytes, found within adipose tissue

  • As adipocytes grow in size and number, fat mass and total weight increase

Adipocytes and Adipokines

• Adipocytes secrete adipokines = messengers that communicate with other body tissues

  • Ex. Leptin (communicates with the brain and other organs)

• Below a certain level of fat mass, adipokine secretion has a health-promoting maintaining effect

• Above a certain level of fat mass (obesity), adipokines are more likely to promote low-grade inflammation and disease

Leptin: The Fullness Hormone

• An adipokine that acts on the brain’s hypothalamus to promote satiety (fullness)

• When our fat cells get larger, more leptin is released - this decreases appetite, promoting an energy deficit

• If leptin production is genetically compromised (extremely rare), obesity results quickly

• Many individuals with obesity are leptin resistant

Obesity is a Chronic Disease

• The state of having an excessive amount of fat stored in the body

• Canadian Medical Association declared obesity a disease in 2015

  • Has a long duration, requires a long-term, systematic approach to management, occurs due to both genetic and lifestyle factors

  • Has physical, mental and social effects

Sick fat disease

• Adipokine secretion shifts to promote chronic low-grade inflammation

  • type 2 diabetes

  • cardiovascular disease

  • certain cancers

  • fatty liver

Fat mass disease

• Added weight promotes biomechanical and structural challenges

  • osteoarthritis

  • joint pain

  • sleep apnea

  • tissue friction

Evidence for the Link Between Genetics and Obesity

• Identical twins have a stronger correlation in BMI than fraternal twins

• When identical twins are overfed, they gain an amount of weight similar to each other, but different to others

• We are likely to have a similar body size/shape to our mother/father at our age

• Genome-wide association studies have found ~100 mutations that are more common in individuals with obesity

  • Mainly found around genes associated with appetite

Genetic and Obesity

• Obesity is rarely caused by a single gene mutation (monogenetic)

• It is polygenetic in nature

• The majority of the genetic differences found in individuals with obesity are found in and around genes involved in hunger regulation

The Complex Causes of Obesity

• Social Psychology

• Individual Psychology

• Physical Activity Environment

• Individual Physical Activity

• Physiology

• Food Consumption

• Food Production

Appetite

• Drive to consume food

Hunger

• Physiological need to consume food

Satiety

• Sense of fullness that makes us stop eating and keeps us feeling full until the next meal

• Our appetite and satiety centres are found within the brain’s hypothalamus

  • Receives constant cues that affect appetite

Food Production

• The abundance of food and food cues in our environment promote a constant stream of signals to provoke high energy consumption

  • Obesogenic environment

  • Our thought interpret what we see, connect it with memory and emotion, and a message may then be sent to our appetite centre about it

• Also, many food offerings are energy-dense and nutrient-poor

Individual Psychology

• Stress, mental health status and the way we think about ourselves and our bodies can affect how much we eat and how much we exercise

• Our emotional brain communicates with our appetite center

  • Sometimes we are not hungry but want to eat in order to cope with something else that is going on

    • Food has a rewarding effect on the brain

Social Psychology

• Psychology of our social surroundings

  • Can affect food preferences, body size acceptance, physical activity

• Our perceived lack of time may compromise our ability to eat healthy and be active

Individual Physical Activity

• Main controllable factor that affects energy expenditure

• Our childhood experiences, physical capacities and perceptions of physical activity can increase/decrease desire to be active

• Furthermore, how much we move our body at work and in our leisure time all contribute in our total energy expenditure

Physical Activity Environment

• Both the natural and built environment can affect our activity levels

• Infrastructure, urban planning, transit, safety, weather can all affect activity level

• Governments can help promote a better physical activity environment

Physiology

• We all handle energy differently

  • Ex. Different BMRs, hormonal activity, genetics

• Also, differences in microbiome and appetite regulation can have significants effects on energy balance

Microbiome and Energy Balance

• Individuals with obesity are more likely to have more Firmicutes in their colon

  • These bacteria are better at harvesting energy from food, increasing energy intake

• There is also mounting evidence of a gut-brain axis that increases obesity risk

  • Communication between microbiota and brain

    • May affect appetite etc.

Key - Appetite Hormones

• Leptin - satiety signal

• Ghrelin - hunger signal

• GLP-1 - satiety signal

Leptin

• Secreted by our cells to alert the brain of their energy status. When our adipocytes get larger due to more fat storage, leptin acts in the appetite centre, promoting satiety and energy expenditure

• This leads to caloric deficit, which can help shrink these fat cells to their former size

Ghrelin

• Secreted by the stomach and has many targets around the body, including hypothalamus.

• Promotes appetite/ hunger

GLP-1

• Secreted by intestinal cells in response to food intake. Signals brain that the intestines have food in them, promoting satiety

Body Composition

• Proportion of fat mass vs lean mass on body

• A body that has more lean mass and less fat mass is associated with health

Weight and Percent Body Fat

• Weight cannot fully capture body composition

• Body Mass Index (BMI) considers body height and weight, but still does not capture body composition

• Percent Body Fat expresses fat mass as a percentage of total mass

  • Better at determining body composition

Visceral vs Subcutaneous Fat

• Subcutaneous fat is located below the skin

• Visceral fat is located within the abdominal cavity, where many internal organs are found

• Visceral adiposity is associated with higher disease risk

Measuring Body Composition

• DEXA/ Dual X-Ray absorptiometry = low dose X-Ray that scans the body in two planes

  • Gives image of the body used to determine body composition

  • Can also indicate bone density and muscle mass

• Air/Water Displacement

Air/Water Displacement

• Air Displacement - A person places themselves in a small pod and the volume of air in the pod before they entered, is compared with the volume after they entered

  • Most accurate of body composition

• Water Displacement - Body mass/ Body volume = body density - body fat percentage

Measuring Body Composition Tools

• Skin Folds: Involves the use of callipers that pinch and measure folds of skin and the fat that lies underneath them

• Bioelectric Impedance: Measures the rate at which electrical current passes through the body and determines its voltage

Body Mass Index

• Useful for population-level data

• Main limitation = does not fully capture body composition

• mass (kg) / height (m2)

Waist Circumference

• Often used in combination with BMI to better assess body composition

• If BMI>30 and waist circumference is above a threshold = obesity, higher health risk

  • Threshold:

    • Men: 102 cm

    • Women: 88 cm

Weight Loss

• Based on one key concept: Consistent Energy Deficit

• Many strategies can achieve this

  • But are they:

    • Healthy?

    • Sustainable?

    • Compatible with our lives?

National Weight Control Registry

• Database of people who have lost 30+ lbs and kept them off for at least two years

Decreasing Food Intake

• Many ways to achieve this including:

  • Tracking food intake/calories

  • Portion control

  • Hunger control

    • Whole foods, protein, fibre, volume-rich foods, eating slowly, eating smaller meals more often

  • Willpower

• A modest caloric deficit of 500-1000 kcal per day can lead to significant changes in fat mass over time. This amount is also more likely to be sustainable compared to more drastic deficits

Willpower

• Our thinking brain’s ability to override other signals

  • Cannot always be relied on

    • Can ve exhausted

    • Is lowest at the end of the day

• Recommend using skillpower in addition to willpower

Physical Activity for Energy Balance

• Physical activity is one of the best things we can do for our overall health

• However, very high levels are needed to promote weight loss

  • 150 minutes per week maintains and improves health

  • 150-250 minutes per week prevent weight gain

  • >250 minutes per week promotes clinically significant weight loss

  • 200-300 minutes per week prevents weight gain following weight loss

Psychological Aspects of Weight Loss and Maintenance

• Our psychological health impacts appetite, desire to be active

• Self-efficacy = belief in our ability to achieve a certain task

  • Setting small, achievable goals, celebrating victories, affirming thoughts can help build it

Emotional Eating

• May be used to cope with negative emotions, feelings

• Positive coping, psychology mechanisms may help decrease it

  • Ex. Talking to others, spending time in nature, journalling, crying, speaking to a counsellor

Mindfulness

• Practice of being aware of and experiencing the present moment with a judgement-free, curious approach

• Ex. Mindful eating, mindfulness meditation

Fad Diets

• Ones that are popular for a period

• Often promise quick results that are not sustainable

• Many people who use fad diets gets stuck on a never-ending fad diet cycle. This patterns doesn’t promote a positive relationship with food and often lead to yo-yo dieting

• If a diet is extreme and/or not compatible with our lifestyle, it is less likely to be successful

Fad Diet Red Flags

• Does not recommend exercising

• Is overly restrictive

• Focuses on foods to avoid

• Significantly limits what foods can be consumed

• Is expensive

• Requires the purchase of supplements, shakes and/or pre-packaged foods

• Endorsed by celebrities and influences who are being paid to promote the product

• Has the word detox or cleanse in the title

Weight Gain

• Some people have a lower body weight and struggle to gain weight

  • May be due to genetics, higher BMR

• Best way to increase lean body mass is through muscle-building exercises

• Can also increase fat mass by increasing caloric intake

Our Best Weight

• One that supports physical, mental, social wellbeing

Pharmaceutical Interventions for Obesity

• Orlistat

• Liraglutide (Saxenda)

• Naltrexone/ Bupropion (Contrave)

Orlistat

• Blocks the activty of lipase in small intestine

• Fat absorption, caloric intake decrease

Liraglutide (Saxenda)

• Increases the activity of GLP-1

• Promotes satiety

Naltrexone/ Bupropion (Contrave)

• Reduces food cravings by altering the reward circuit in the brain that drives food-seeking behaviour

Bariatric Surgery

• Roux-en-Y gastric bypass

• Sleeve gastrectomy

• Gastric Banding

• Promotes weight loss by altering stomach.

• Promotes satiety & decrease in energy intake

Roux-en-Y gastric bypass

• A small upper part of the stomach is sectioned off from the rest of the stomach. It is then attached to the jejunum of the small intestine. Food bypasses most of the stomach as well as the duodenum. Not reversible

Sleeve gastrectomy

• A banana-sized portion of the stomach is removed entirely. The overall size of the remaining stomach is significantly smaller. Not reversible

Gastric Bending

• An inflatable device is placed around the upper part of the stomach. Food must be partly digested in this upper part before passing though the narrow opening in the stomach allowed by the hand. Reversible

Risk Factors for Eating Disorders (EDs)

• EDs are multifactorial

• Contributing factors may include:

  • Genetics

  • Female gender

  • Socio-cultural factors

    • Ex. Pressure to be thin

  • Personality

    • Ex. Perfectionism, sensitivity towards reward and punishment

  • History of sexual/physical abuse

Binge Eating

• Occurs in bulimia and binge eating disorder and sometimes in anorexia

• Main symptoms = loss of control eating

• A binging episode:

  • Occurs in a specific amount of time (ex. 2 hours)

  • Typically occurs in the absence of hunger, is typically at a fast rate, occurs while the person is alone, and is associated with feelings of guilt and shame

Bulimia Nervosa

• Involves binge eating episode + compensation

  • Ex. Vomiting, excessive exercise, laxatives

• Risk Factors:

  • Preoccupation with food

  • Distorted perceptions around body weight

  • Depression

  • Frequent dieting increase risk

• Vomiting can damage teeth, cause electrolyte imbalance

Binge Eating Disorder

• Most common eating disorder

• Binge eating without compensation

• Promotes obesity and its related complications

• Risk factors include:

  • Frequent dieting

  • Inability to interpret hunger/satiety signals

Anorexia Nervosa

• Significant restriction in energy intake leading to a unhealthfully low body weight

• Individuals with anorexia often:

  • Have an intense fear of weight gain

  • Feel disturbed by their weight/shape

  • Struggle with self-worth and acceptance

  • Experience Amenorrhea - a cessation in menstruation

• It is the psychiatric disorder with the highest mortality rate

Night Eating Syndrome

• Currently not recognized as own eating disorder

• Increases obesity risk

• Proposed diagnostic criteria:

  • Abnormal increase in food intake at night

    • >25% of calories consumed after dinner

  • Lack of morning hunger

  • Insomnia

Orthorexia Nervosa

• An obsession with eating healthy that has negative psychological implications

  • It is the obsession and negative mental health implications of these restrictions that may cause it to be a disordered eating pattern

  • Also increases risk for micronutrient deficiencies

• Believed to be promoted by societal pressure toward ‘clean eating’

• Signs:

  • Compulsively checking nutrition labels

  • Cutting out foods, nutrients, etc.

  • Limiting food intake to narrow range of foods

Treatment for Eating Disorders

• Typically begins with diagnosis by health care professional

  • However, symptoms often go unrecognized

• Main treatment strategies are psychological

• Medication may also be prescribed

  • Ex. Cognitive behavioural therapy (CBT)

Physical Activty

• Any voluntary movement of the body that expends calories

• Any activity that burns energy

• PA recommendation:

  • 150 min of mod-vig PA week accumulated 10 min at a time

  • +two days per week of resistance training

Exercise

An activity that is planned, structured and whose goal is to promote fitness

Sport

• An activity that is planned, structured, and has an element of competition

Occupational activity

• Activity done as part of work

Leisure activity

• Activity done as part of leisure activities

Active living

• A lifestyle that includes multiple chances for physical activity

Benefits of Regular Physical Activity

• Improves social health

• Strengthen bones and muscle

• Improves heart and lung function

• Improves quality of life

• Promotes a healthy energy balance

• Improves mental health

• Improves flexibility

• Reduces risk for CVD, diabetes, cancer, obesity, osteoporosis, depression

Fuel Use

• Which fuel (energy source) is preferentially used depends ons:

  • Duration of PA

  • Intensity of PA

    • i.e. whether PA is aerobic or anaerobic

PA Duration vs Fuel Use

• The first ~two minutes of exercise are anaerobic

  • Relies on

    • ATP (used up in ~2 s)

    • ATP-CP system (used up in ~10 sec)

    • Anaerobic glycolysis

• At a moderate intensity, after two minutes, aerobic metabolism dominated

  • Relies on

    • Aerobic glycolysis

    • Aerobic fatty acid metabolism

Creatine Phosphate-ATP System

• Creatine phosphate helps to replenish ATP by donating its phosphate group

  • Helps fuel anaerobic activities

• This creatine system is the main energy pathway that fuels activities that fuels activities from the point ATP is depleted to approximately the first 10 seconds of exercise

Glycolysis

• Break down of glucose

  • Glucose is the only dietary fuel that can be used for anaerobic activities

    • Fuels high intensity activities and the first 11-120 seconds of exercise

Aerobic Fuel Use Following the First Two Minutes of Exercise

• Glucose use decreases over time

  • Comes from:

    • Muscle glycogen

    • Blood glucose

• Lipid metabolism is the main fuel source following the first 20 minutes of exercise

  • Comes from:

    • Muscle triglycerides

    • Adipose tissue lipid stores

Fuel Use vs Exercise Intensity

• Low-moderate intensity activities = aerobic zone

  • Can use all fuels

  • Preferential use of lipids

• High intensity activities = anaerobic zone

  • Can only use glucose, ATP-CP for anaerobic processes

  • However, some aerobic metabolism will still take place - can use aerobic lipid metabolism as well

The Misleading Fat Burning Zone

• Many cardio machines have both a ‘cardio zone’ (higher intensity, where glucose is preferred fuel source) and a ‘fat-burning zone/weight loss zone’ (lower intensity, where fat is the preferred fuel source)

• While the % of Calories burned from fat is higher in the fat burning zone, you will burn more total Calories in the cardio zone

Carbohydrate Intake

• Glucose is a fuel for both aerobic and anaerobic activities

  • However, we store a limited amount as glycogen

• Consuming sufficient carbohydrates can maximize glycogen stores

Protein Intake

• Protein is essential for the growth and repair of tissues

• Muscle synthesis increases in 24 hours following exercise

• Protein recommendations increase for athletes

  • From 0.8 g/kg body weight to 1.2-2 g/kg body weight

Summary of Additional Nutrient Requirements for Athletes

• The body stores lipids and extra dietary consumption is not typically recommended for an athlete, especially if it displaces carbohydrates in the diet

• Athletes should ensure adequate intake of both calcium and vitamin D. Important for those with lower EA who may be lacking in these and other micronutrients

• Increasing iron intake from food is the primary strategy for reducing the risk of iron deficiency in athletes

Pre-Exercise

• Pre-exercise meal should be properly timed and have the right balance of nutrients to promote performance and minimize digestive issued

• A pre-exercise meal that contains carbohydrates is the best established way to maximize time to exhaustion

  • Recommendations: 1-4 g/kg body weight of carbs 1-4 hours before exercising for more than 60 minutes

    • Favour easily digestible carb sources that are low in fibre and fat

      • Minimizes digestive distress

• Fluid intake is also important

Glycogen Supercompensation

• Aka carbo-loading

• Maximizing glycogen stores before a long bout of endurance exercise (ex. half-marathon)

• Method: in the two days before event, consume 10-12 g/kg body weight per day

  • Maximizes time to exhaustion during event

During Exercise

• Water is the most important nutrient to consume during exercise

  • Can weigh yourself before/after exercise to see how much water was lost, replenish the same amount next time

    • i.e. lose 1 kilogram of weight = 1 L of lost water

• For longer bouts of activity, electrolytes also need to be replenished

• These both help stave off the effects of dehydration

Fuels During Exercise

• If exercising for less than an hour, no extra fuel is needed during exercise

• Endurance activities lasting 60+ minutes may require extra fuel

  • Recommendation = 30-60 g/hour of easily digested carbohydrate

    • Ultra-endurance athletes (2.5+ hr) may require up to 90 g/hour

Post-Exercise

• We have three nutritional priorities following exercise:

  • Promote muscle growth and repair (protein)

    • Protein sensitivity is highest in two-hours following exercise

    • Recommendation: 0.25-0.3 g/kg body weight with 10 g of essential amino acid

  • Refill glycogen stores (carbohydrates)

    • Glucose transport into muscle cells increases in 30-40 minutes following exercise

  • Replenish lost fluids and electrolytes

Creatine

• Help to maximize muscle creatine stores

  • Important for anaerobic activities

• Also may enhance muscle mass, glycogen synthesis, recovery

• May promote weight gain due to water retention, as well as diarrhea, abdominal discomfort

  • However, generally well tolerated

Protein Supplements

• Athletes do require extra protein, but it can come from whole foods

• Branched chain amino acids may also reduce moderate muscle damage

  • But, again can be consumed from whole foods

Caffiene

• Psychoactive drug

• Improves exercise performance by increasing

  • muscular strength and endurance

  • Aerobic endurance

  • Anaerobic power

• Recommendation:

  • 3-6 mg/kg body weight

  • Consume in a form without water

    • Coffee, tea may cause digestive discomfort

Hydroxymethybutyrate (HMB)

• Compound produced by the breakdown of essential amino acid leucine

• Decreases protein breakdown while increasing protein synthesis

  • May improve muscle recovery by decreasing muscular damage

Other Ergogenic Acids

• Vitamin and mineral supplements

• Anabolic steroids

• Cannabic

Vitamin and mineral supplements

• Can only fix a deficiency