hnsc 1210 unit 9 - energy balance and a healthy body weight

weight and health

• body size alone does not equal health

• body composition (fat, muscle, bone, and tissue that make up body weight) is most related to health outcomes

• being overweight or underweight can present health problems in some individuals

energy balance

• occurs when calories coming into our body (energy intake) equal the calories that our body is expending (energy expenditure)

• energy intake comes from food and beverages we consume - contribute to calories

• if you had 1 cup of juice at breakfast, a 120z glass of ice tea at lunch and a 12 glass of coke at supper this would approx. 400 calories to your day

food intake regulation

• internal and external factors that contribute to obesity

• appetite

• eating behaviour is regulated by “go: mechanisms that simulate eating (hunger and appetite) and “stop” mechanisms that signal the body to cease/refrain from eating (satiation and satiety)

hunger

• physiological need to eat

• unpleasant sensation that demands relief, a drive to obtain food

• much more powerful stimuli that satiety and protein is the most satiating of the nutrients

appetite

• physiological desire to eat

• learned motivated and a positive sensation that accompanies the sight, smell, or thought of appealing food

satiation

• perception of fullness that builds throughout a meal, eventually reaching the degree of fullness/satisfaction that stops eating

• generally determines how much food is consumed in one sitting

satiety

• perception of fullness that lingers after a meal, inhibiting eating until the next meal

• determines the length of time between meals

hunger, appetite, satiation, and satiety

food intake regulation: inside the body

• many factors that regulate food intake inside of body: hormones

leptin

• appetite suppressing hormone that is produced in fat cells

• coveys information about body fatness to the brain, working to suppress appetite and food intake between meals 

• some produced in stomach

leptin feedback loop

• ↑ Body fat → ↑ leptin → ↓ appetite

• ↓ Body fat → ↓ leptin → ↑ appetite

what happens when an organism cannot produce leptin

• severe obesity due to uncontrolled appetite (ex. genetically obese mouse without leptin gene)

why is the genetically obese mouse given leptin lean?

• external leptin restores appetite regulation and prevents overeating

besides leptin, what internal factors affect food intake

• microbiota

• inborn appetite

• disease states

• sleep deprivation 

food intake regulation: outside the body factors

• environmental and emotional influences that affect how much and what we eat

how does pleasure influence food intake

• some people eat more because food provides enjoyment, comfort, or satisfaction

what food items do people have a tendency to overconsume

• delectable items

• sweats

• snacks

• condiments

• main dishes

What is the “variety effect” on eating behavior?

• People tend to eat more when offered many food choices (e.g., buffets) compared to meals with fewer options.

What emotions commonly lead to overeating?

• Boredom, loneliness, sadness, and even happiness.

• consuming food in response to emotions rather than hunger cues

outside factors contributing to obesity and overweight

• over eating can occur due to a number of factors:

• stress

• time of day (ex. break)

• food pricing and availability (ex. healthy foods expensive)

• advertisement (ex. food marketing budgets)

• physical inactivity

What are the three ways the body expends energy?

1. basal metabolic rate (BMR)

2. voluntary activity

3. thermic effect of food

What is BMR?

• sum of all involuntary activities necessary to maintain life, excluding digestion and voluntary activities

• e.g., circulation, respiration, temp maintenance, hormone secretions, nerve activities, and new tissue synthesis

• varies from person to person

What is voluntary activity in energy expenditure?

• Intentional activities such as walking, sitting, running, etc. conducted through voluntary muscle movements.

What is the thermic effect of food?

• The body’s metabolism speeds up for approximately five hours after a meal.

Which component accounts for the greatest portion of energy expenditure?

• Basal metabolism (BMR).

Rank the components from largest to smallest contribution.

• BMR → voluntary activity → thermic effect of food.

What happens when energy intake exceeds energy expenditure?

• Excess energy is stored as fat in fat cells.

factors that affect BMR

• age, higher  in children and creases with age

• height, taller people have higher BMR because more surface area

• period of growth, have a higher BMR (ex. children and pregnancy)

• body composition, more lean muscle mass higher BMR

• fever and stress, increase BMR

• environmental temp., increases BMR

• fasting, starvation, malnutrition, lower BMR (make weight loss tricky)

• thyroxine, higher levels, higher BMR

when energy intakes exceeds energy expenditure

• excess fat accumulates in fat cells

how much fat do your store for each 3,500 calories you eat excess in expenditure

• one pound of fat

how much fat do you lose for each 3,500 calories that you expend in excess of need

• one pound

• to lose 1 pound of fat in one week, need to expend 500 calories per day

what does the body do when energy intake is less than energy expended

• body draw on fat stores

to loose one pound of fat

• must expend 3,500 calories more then you consume

estimated energy requirement (EER)

• calculation to determine the number of calories your body needs

how to calculate EER

1. find equation for your gender below

2. insert age in years, weight (wt) in kg, height (ht) in meters

3. your physical activity number (PA) found on table

4. equation

• women age 19 years or older: EER = 354 - 6.91 x age + PA x [9.36 x wt) + (726 x ht)

• men age 19 years or older EER = 662 - 9.53 x age + PA x [{15.91 x wt) + (539.6 x ht)]

EER calculations should take into account

• Gender: because body composition differs between men and women, which will affect energy requirements

• Age: because energy requirements decrease as we age

• Height and weight: because energy requirements are higher for those taller or heavier

• Physical activity level: because physical activity will use more energy

calculation for BMI

• your weight in kg divided by your height in meters squared (to convert lb to kg – divide wt in lbs by 2.2. To convert ht in inches to ht in cm, multiply ht in inches by 2.54).

BMI

• weight in kg/(height in m)2

• used to evaluate a person health risk associated with being underweight and overweigh

• more affecting for assessing degree of weight

BMI scale

• Underweight BMI: <18.5

• Normal weight BMI: 18.5-24.9

• Overweight BMI: 25-29.9

• Obese (class I) BMI: 30 – 34.9

• Obese (class II) BMI: 35 – 39.9

• Extreme Obesity (class III) BMI:  >40

BMI used as proxy for

• health behaviours, fitness, dietary quality and interventional adherence in older literature when we should instead measure these directly.

What do World Health Organization and National Institute of Health normal BMI ranges help predict?

• Lower risk for certain diseases, such as Type II Diabetes

Why is using the same BMI ranges for men and women flawed?

• It can misclassify chronic disease risk, especially in individuals labeled “overweight.”

What key factor does BMI fail to account for between men and women?

• differences in adiposity (body fat levels).

How do adiposity levels naturally differ between men and women?

• Women typically have higher adiposity than men.

Why is BMI not a good tool to measure health status?

• It oversimplifies health and can misclassify both larger-bodied and smaller-bodied individuals.

How does BMI misclassify people in larger bodies?

• It may label healthy, fit individuals as “unhealthy” solely based on weight.

How does BMI misclassify people in smaller bodies?

• t may label unhealthy individuals as “healthy” if they are slim, even if they have poor lifestyle habits.

Who created BMI and for what purpose?

• A mathematician in the 1800s developed BMI to categorize populations—not to assess individual health.

Does BMI accurately predict a person’s health?

• No, BMI was not based on health measures and does not predict individual health outcomes.

What important factors does BMI fail to measure?

• Muscle mass, bone mass, and fat mass (body composition).

Why can BMI give a misleading impression of someone’s health?

• It doesn’t consider lifestyle factors, metabolic health, or behaviors like smoking or alcohol use.

Give an example of how BMI can mislead health status in a slim person.

• A slim person who smokes and drinks daily may have a “healthy” BMI but poor actual health.

BMI limitations

• need to compare all body mass and size, i.e looking at all different dog species, not just fat and skinny poodles

anthropometry

• A slim person who smokes and drinks daily may have a “healthy” BMI but poor actual health.

waist circumference

• measures visceral fatness and disease risk.

• You measure around the body at a point near the belly button. The person should exhale normally when the measurement is taken.

• A higher waist circumference can indicate an increased risk of disease even if BMI is normal.

visceral fat

• Fat stored in the abdominal cavity associated with an increased risk of disease (e.g. CVD, diabetes, stroke, hypertension).

What is central obesity?

• Fat carried around the abdomen/stomach area (apple shape).

What is lower-body fat distribution?

• Fat carried around the hips, thighs, and buttocks (pear shape).

Which body shape is considered less risky?

• Pear shape (fat stored in lower body).

Why is apple shape linked to higher disease risk?

• Central fat is more metabolically active and increases risk of chronic diseases (like heart disease, diabetes, etc.).

Which body shape is associated with lower risk: apple or pear?

• Pear shape has lower risk; apple shape has higher all-cause mortality risk.

fat fold test

• measure the thickness of a fold of skin at areas on the body using calipers

• often back of arms, below shoulder blade, or skin from waist is tested and compared to standards

• also called skin fold resr

• provide estimate of total body fat and where fat is located

• should be done by trained technician repeated

three methods of assessing body fatness

1. density (underwater/air displacement)

2. conductivity (BIA)

3. radiographic techniques (DEXA)

• accuracy depends on skill of clinician performing test. if going for repeat have the same clinician perform the test

What is the density method of assessing body fatness?

• Measures body weight compared to volume; lean tissue = denser than fat. Determined by underwater weighing or air displacement.

What is the conductivity method of assessing body fatness?

• Measures how well the body conducts a small electrical current; lean tissue + water conduct electricity. Hydration status affects accuracy (overhydration → underestimates fat; dehydration → overestimates fat).

• disadvantage: body’s water component can impact results, conducts electrical charge over hydration can underestimate body fatness, and dehydration can overestimate body fatness

What is the radiographic method of assessing body fatness?

• Uses dual-energy X-ray absorptiometry (DEXA) to differentiate fat, lean tissue, and bone; provides precise measurements but is expensive and less accurate in extremely obese individuals.

• disadvantage: expensive and not represent an accurate picture in extremely obese individuals

ideal amount of body fat for health depends on?

• age and gender

maximum recommended body fat

• Men under 40 years: 22%, over 40 years: 25%

• Women under 40 years: 32%, over 40 years: 35%

besides gender and age, standards differ because of

• lifestyle and stage of life

Why do competitive endurance athletes often have lower body fat?

• They need just enough fat for fuel, insulation, and fat-soluble hormone activity; extra fat can hinder performance.

Why might northern fishermen have higher body fat?

• Higher body fat provides insulation against cold temperatures.

How does body fat level affect pregnancy outcomes?

• Too much or too little body fat can compromise pregnancy.

How does low body fat affect fertility?

• Very low body fat can lead to infertility in some individuals.

How can high body fat impact fertility?

• Excess body fat may also make it harder for some individuals to become pregnant.

Does losing weight automatically mean someone is healthier?

• No. Health is based on behaviours (like walking and reducing soda), not just weight change.

What does research say about improving health?

• Many behaviour changes improve health even without weight loss.

factors that effect weight

• Genetics

• Age

• Hormones

• Some medications

• Some medical conditions

• Family habits and culture

• Social determinants of health

• And many more...

how can we improve our health other than diet and excercise?

• following healthy eating habits like balanced diet, regular exercise, limiting alcohol, and not smoking

• reap health benefits of those activities, no matter how much we weight

why does doing these health eating habits not necessarily mean you will lose weight

• body weight is an OUTCOME based on may factors

• cannot directly control our weight because we cannot control all factors that determine weight

• weight itself is not a behaviour or direct action, outcome

social determinants of health

• broad range of person, social, economic, and environmental factors that determine individual and population health

main determinants of health

1. Income and social status

2. Employment and working conditions

3. Education and literacy

4. Childhood experiences

5. Physical environments

6. Social supports and coping skills. Did you know that maintaining social connections by engaging with family and friends can improve your health? Social support accounts for 30% of our health outcomes.

7. Healthy behaviours

8. Access to health services. Access to health care is another major effect on your health.  You can improve your health by attending routine doctor's appointments and attending a class like this one today.  As well, it’s important to find a health care provider that you feel comfortable, with so you are able to engage in preventative health care and also receive treatment when you are unwell. 

9. Biology and genetic endowment. Genetic endowment means that the genetics we inherit predispose us to a wide range of individual responses that affect health status. As discussed in Unit 1, there are certain conditions that are genetically inherited (sickle cell anemia, hemophaelia) which may not be affected by lifestyle behaviours, and others that are somewhat influenced (for example diabetes or cardiovascular disease risk which may also be inherited).

10. Gender

11. Culture

12. Race / Racism

What are health inequalities?

• Differences in health status between individuals or groups caused by factors like genes, lifestyle choices, and social conditions.

How do social determinants influence health?

• Factors like income, location, and access to resources (e.g., nutritious food) can lead to differences in health outcomes.

What are health inequities?

• Unfair, unjust, and modifiable differences in health caused by social disadvantages (e.g., limited access to healthy foods in remote areas).

Give a Canadian example of a health inequity.

• Canadians in remote or northern regions often lack access to affordable, nutritious foods like fruits and vegetables, putting them at higher risk for poor health.

What does research say about dieting for weight loss?

• Diets typically don’t work long-term; most people regain the weight, so weight loss is not the key measure of health.

practice of diet to lose weight can result in

• Lower metabolism; we store fat more easily from eating fewer calories

• Increased hunger and food cravings

• Decreased attention span, fatigue, irritability

• Decreased muscle mass

• Poor nutritional intake

• Feeling "obsessed" or fixated on food

• Feelings of failure; reduced self-esteem

what is weight cycling

• repeatedly losing and gaining weight, also sometimes referred to as yo-yo dieting

weight cycling can increase

• Mortality / risk of death

• Risk of coronary heart disease, heart attack and stroke

• Risk of type 2 diabetes

• Risk of some types of cancer

• Risk of osteoporotic fractures

• Blood pressure

• Likelihood of over-eating in stressful situations 

• Weight independent of BMI and age

• Inflammation

• Likelihood of binge eating

• Emotional distress

weight cycling can decrease

• Immune function

• Metabolic rate

• Physical activity (secondary to fatigue, lack of energy, etc.)

• Muscle mass

• Self-esteem

What does “eat well” mean in weight-inclusive health?

• Eat enough food, include variety, plan meals, avoid long gaps, and listen to hunger/fullness cues.

What is the recommended amount of activity per week?

• 150 minutes/week (e.g., 30 min × 5 days), but even 5–10 minutes daily improves health.

Why is good sleep important?

• Lack of sleep increases stress hormones, food cravings, and risk of diseases like diabetes and high blood pressure.

How does stress affect health?

• chronic stress harms physical and mental health; even 10 minutes of enjoyable activity helps reduce stress.

Why is quitting smoking important for health?

• It reduces risk of heart disease, diabetes, COPD, and many cancers; benefits start within hours of quitting.

Why is having fun and connecting with others important?

• Social connection improves physical and mental well-being.

Why is regular medical care part of weight-inclusive health?

• Helps detect, prevent, and manage health conditions early.

How do healthy behaviours affect health?

• Each healthy behaviour you adopt significantly reduces your risk of death—regardless of body size or weight.

How much can one or two healthy habits reduce risk?

• One habit can cut risk almost in half; two habits reduce risk by an additional 50%.