Week 5 - Nutrition and Weight Management (+ Chapter 17 - Health and Weight Management)

Nutrition

science of food and how the body uses it

macronutrients vs. micronutrients

• macronutrients - protein, fat, carbohydrates

  • provide the body with energy

• micronutrients - many vitamins and minerals

functional foods

offer unique health benefits that go beyond simply meeting basic nutritional needs by helping reduce the risk of chronic disease

• ex. antioxidants, food with vitamin C, E, beta-caroene

Nutraceuticals

purified preparations of health promoting bioactive compounds that have been extracted from foods and refined

• ex. probiotics (health-promoting microorganisms in intestines)

Carbohydrates

type of macronutrient

• is a primary energy source (55-60% daily caloric intake)

• ex. sugar and starches

sugar

type of carbohydrate

• sugary foods tend to be high in fat and high in calories

• can lead to cavities in teeth

• ex. glucose

  • is body’s primary fuel source

starch

complex carbohydrates

• get broken down to simple sugar

• ex. vegetables, fruits, grains

Glycemic Index (GI)

ranks carbohydrates based on their effect on blood glucose

Low GI foods vs. High GI foods

• Low GI foods - have health benefits including lower risk of diabetes, control of diabetes, and lower risk of heart disease

  • ex. beans and legumes, whole wheat bread, oats, fruits, and vegetables

• High GI foods - produce large increase in blood glucose and support refueling after strenuous exercise

  • ex. candy, sugary drinks, white bread, white rice, french fries

Fat

type of macronutrients

• source of energy insulates the body

  • most concentrated source of energy

• includes lipids and fatty acids

Saturated fats vs. unsaturated fats

• saturated fats - more solid at room temp.

  • animal fat (meat, dairy, eggs, baking),

  • associated with risk of heart disease

• unsaturated fats - liquid at room temp.

  • plant source (nuts, beans)

  • includes monounsaturated and polyunsaturated

Cholesterol

lipid in the blood

• has 2 lipoproteins that act as cholesterol carriers:

  • low-density lipoprotein (LDL)

  • high-density lipoprotein (HDL)

triglycerides

another type of fat in the blood

Protein

type of macronutrient

• 15% of daily intake

• made of amino acids

• adults have 0.8g protein per kg of body weight

Complete vs. incomplete proteins

• complete proteins - animal products

  • contain all amino acids

• incomplete proteins - plant-based products

  • don’t contain all amino acids

    • but still good sources of amino acids

how much of the 3 major nutrients should we eat

• carbohydrates - 55%

• fats - 30%

• proteins - 15%

vitamins

organic substances that are required for normal growth, reproduction, maintenance of health

• can dissolve in water and fat (water-soluble and fat-soluble)

• don’t provide calories and instead serve as coenzymes

recommended amount of water we should drink

8 glasses of water per day

what drink contents are recommended during intense exercise

drinks containing carbohydrate concentrations and sodium are recommended for use during intense exercise longer than 1 hour

fibre (and 2 types of fibres)

plant substances that can’t be digested

• not a nutrient but still an important element in our body

• helps to reduce cholesterol, maintain blood glucose, improves elimination possibly preventing colorectal cancer

• 2 types:

  • soluble fibre - has ability to bind cholesterol-containing compounds in intestines

    • this lowers blood cholesterol levels by cleaning cholesterol from the intestinal tract

    • slows the body’s absorption of glucose

  • insoluble fibre - absorbs water from intestinal tract which prevents constipation

Canad’s new food guide

updated in 2019

major changes from previous version

• less focused on food groups

• focused on healthy behaviours (actionable items)

• addresses social and cultural factors

• updated recommendations and guidance on sugary drinks

• additional resources (like recipes) available online and on apps

Canada’s food guide

eat a variety of healthy foods each day

• have plenty of vegetables and fruits

• eat protein foods

• choose whole grain foods

• make water your drink of choice

Healthy eating recommendations on Canada’s food guide

• be mindful of your eating habits

  • take time to eat

  • notice when you’re hungry and when you’re full

• cook more often

  • plan what you eat

  • involve others in planning and preparing meals

• enjoy your food

  • culture and food traditions can be a part of healthy eating

• eat meals with others

• eat plenty of vegetables and fruits, whole grain foods and protein foods

  • choose foods that come from plants more often

  • choose foods with healthy fats instead of saturated fat

• limit highly processed foods and if you choose these foods, eat them less often in small amounts

  • prepare meals and snacks using ingredients that have little to no added sodium, sugars, or saturated fats

  • choose healthier menu options when eating out

• make water your drink of choice and replace sugary drinks with water

• use food labels

• be aware that food marketing can influence your choices

Energy Balance

energy intake and energy expenditure

weight gain

Intake more calories than you expend

basal metabolic rate (BMR)

energy needed to maintain basic body functions

• BMR is relatively high at birth and continues to increase until 2 years old

• Gradually decreases with age (except for rise at puberty)

BMR calculation

BMR per day = 1 C x body weight (kg) x 24

Total energy expenditure calculation

Total energy expenditure = BMR + energy expended during activity

Ways to change energy balance

• eat 5-6 healthy meals/day with reduced calories and more fibre

• add resistance training

• be active during the day

• include planned exercise

• add intense exercise component to increase EPOC

• keep in mind that exercise should be enjoyable to support adherence

body composition

amount of fat, muscle, bone, and organs

lean body mass (LBM) (and calculation)

non-fat tissue

• consists of skeletal muscle, bone, and water

• LBM = total body mass - total body fat

types of total body fat (fat body mass)

• essential fat - makes up 3% of body weight for average man and 12% of for average woman

• storage fat - energy reserve and protects internal organs by cushioning them

  • includes subcutaneous fat and visceral fat

  • subcutaneous fat: accumulates beneath skin surface

  • visceral fat: accumulates in and around organs

2 ways of measuring body composition

• direct method - cadaver analysis only

• indirect

indirect methods of measuring body composition

• skinfolds - subcutaneous fat to predict total

• hydrostatic weighting - most accurate but not practical

  • based on buoyance and water displacement)

• WHR (waist to hip ratio) and WG (waist girth or wast circumference)

• Bioelectrical Impedance Analysis (BIA) - measures speed of electrical conductivity between fat free mass and fat mass

  • influenced by hydration, menstrual cycle

• DEXA - also measures bone density

• BMI (body mass index) = weight (kg) / height (m²)

obesity

chronic, complex disease characterized by excess body fat that can impair health

• BMI > 30

  • (healthy BMI should be 18.5 to 24.9)

• fat mass is greater than 25% in men, and greater than 32% in women

• about 35% of Canadian adults are overweight, 27% are obese and more than 30% of children are overweight or obese

health impacts and risks of obesity

• physical

  • increased risk of heart disease

  • diabetes (type 2)

  • high blood pressure

  • stroke

  • asthma

  • arthritis

  • falls

  • certain cancers

  • sleep apnea

  • pregnancy complications

• psychological

  • low confidence

  • social stigma

  • inability to participate

  • increased risk for depression

factors contributing to excess body fat

• genetics - impact size, fat distribution, metabolism

• metabolism - driven by genetics and lifestye

• hormones - impact metabolism, fat distribution, hunger

• environment - obesogenic environment where unhealthy food is easily accessible, environment is designed for inactivity

• psycho-social - socioeconomic status, or eating as a tool to manage emotions

• lifestyle - physical activity, healthy eating, sleep

dieting

healthy lifestyles with behaviours that can be sustained

• chronic dieting can lead to:

  • impaired growth

  • menstrual irregularities

  • decrease in BMR

  • disordered eating

  • unhealthy relationship with food

• important to differentiate between professional coaching and prescription vs. social media disinformation

Anorexia Nervosa vs. bulimia nervosa

• anorexia nervosa - psychological condition that has physical and psychological impacts

  • failure to eat adequate amount of food to maintain a reasonable body weight

• bulimia nervosa - bing eating disorder

• both can lead to the female athlete triad

skinfold

most common indirect method of measuring body composition

• measures skinfold thickness with skinfold calipers

• used to predict or estimate total body fat based on assumption that subcutaneous fat is directly related to total body fat

• performed by pulling skin away from muscle and muscle is pinched between two flattened prongs of the fat calipers

hydrostatic weighing (underwater weighing)

indirect method of weighing body composition

• based on Archimedes’ principle of water displacement

  • since bone and muscle are more dense than water, person with high fat-free mass percentage will weigh more in the water than a person with a high body fat percentage

  • determines body weight density by measuring

    • body weight on land

    • underwater body weight

    • water density at temp. used for the test

    • residual lung volume (amount of air left in the lungs after a forceful expiration)

waist circumference

indirect method of measuring body comp.

• wrapping tape measure around torso or near belly button

• unhealthy measurement for men - 102 cm (40 inches) or greater

• unhealthy measurement for women - 88 cm (35 inches) or greater

Bod Pod

indirect method of measuring body comp.

• device that is very expensive but accurate and doesn’t require underwater submersion

• may allow for measuring very heavy or large individuals

Bioelectrical impedance analysis (BIA)

indirect method of measuring body comp.

• based on differences in electrical conductivity between fat-free mass and fat mass

• electrical current is passed through the body

  • change in voltage is detected which allows body density and percent body fat to be calculated

• disadvantage: extent to which measurements are influenced by hydration level of subject

is BMI useful for everyone

no, BMI isn’t always an accurate measure of body fat

creeping weight gain

slight change in the energy balance occurring over a period of time that causes a gradual increase in fat mass each year

• related to how obesity is often the result of too little activity rather than overeating

• as people age, metabolic rate and physical activity patterns decline

  • if caloric intake is not reduced to balance with energy expenditure, then body mass will increase due to excess calories stored as fat

energy balance equation

describes relationship between energy input and expenditure

• left side of equation - calories burned through exercises and other bodily processes

• right side of equation - calories consumed in food

• weight remains constant if caloric input and output are the same (caloric balance)

• excess calories are stored as fat as the rate of 3,500 calories equalling one pound

• person gains weight when energy input exceeds energy output

  • loses weight when opposite occurs

how does exercise influence BMR (and why its important for weight management)

exercise increases body’s need for energy significantly beyond basal metabolic needs

• increases total number of calories your body burns each day

• makes it easier to reach calorie deficit needed for weight loss

TEF, NEAT, TEPA, and EPOC

• Thermic Effect of food (TEF) - energy expended in the digestion of food

• Non-exercise activity thermogenesis (NEAT) - energy expended due to daily activities

• Thermic effect of physical activity (TEPA) - energy expended due to planned physical exercise

• excess postexercise oxygen consumption (EPOC) - energy expended after exercise has ceased due to increased metabolic rates