Chapter 10: Energy Balance Flashcards
define: energy
the ability to do work
define: energy intake
Energy intake: energy obtained from the food we eat
What are the 3 energy yielding nutrients? What also yields energy but is not a nutrient?
- carbohydrate, lipids, proteins
- alcohol
Where is energy found in a molecule?
found in the bonds that hold molecules together
During cellular respiration ____ are broken to retrieve the energy
bonds
define: energy expenditure
Energy expenditure: energy used to fuel basal metabolism, physical activity, processing food
define: basal metabolic rate; how much burned energy does it account for?
Basal metabolic rate (BMR): amount of energy the body needs to perform life sustaining functions over a period of time
- 60-75%
What are factors associated with a higher BMR (5)? What is the main controllable one?
- Genetic factors
- Male sex
- Younger age
- Taller height
- Higher lean body mass (main controllable factor)
Define: diet-induced thermogenesis; how much burned energy does it account for?
Diet-induced thermogenesis: thermic effect of food
- 10% of energy expenditure (max 15%)
Fill in the blank: Diets high in ____ promote a higher thermic effect. Diets high in _____ promote a lower thermic effect
- Now explain why
- protein
- fats
- because more energy is required to process proteins and less is required for fats
Define: physical activity; how much burned energy does it account for?
Physical activity: body’s voluntary movement that leads to the expenditure of calories (~15-30%)
How is energy stored in the body
- Some stored as carbohydrates in the form of glycogen
- Most stored as fat within the vacuoles of adipocytes: fat cells
- In the vacuole, energy is stored in the form of triglycerides, fatty acids, and fat soluble vitamins
Fill in the blank: Adipocytes can ____ when they reach maximum size
- divide
How is energy retrieved in the body. Where is most energy retrieved from?
- glucose and amino acids are metabolized to form ATP
- glycogen is converted into glucose
- body proteins are converted into amino acids
- most energy is retrieved from adipocytes; fatty acids and triglycerides are released into the blood
Why is maintaining lean mass important when in an energy deficit?
Body proteins are also used for energy when we are in an energy deficit; maintain lean body mass to make sure you don’t lose muscle
Describe some reasons we can gain weight
- increase lean mass by increasing muscle and bone mass through resistance exercise
- consistent energy surplus leads to fat mass increase
- body water content leads to fluctuations
- increase glycogen storage (max 1-2kg of weight)
Fill ion the blank: More cells an individual has, the greater room for _________
water volume in the extracellular space
When we lose weight, where does it go?
Weight is lost through the air we breathe out (water and carbon dioxide)
If 10kg of body fat is metabolized, how much becomes water and how much becomes carbon dioxide?
1.6kg as water and 8.4kg as carbon dioxide
What are some problems with obesity
- Psychiatric and psychological problems; depression and low self-esteem
- Asthma and breathing problems at night (sleep apnea)
- Gallstones
- Type 2 diabetes
Gynecological problems including an abnormal menstrual cycle and infertility - Cardiovascular disease including high blood lipids, atherosclerosis, hypertension, and stroke
- Breast, colon, prostate, and uterus cancer
- Arthritis
define: adipocytes
Adipocytes: fat cells; secrete adipokines. stores energy in vacuoles in the form of triglycerides, fatty acids, and fat soluble vitamins
define: adipokines
Adipokines: messengers that communicate with other body tissues
Fill in the blank:
- Below a certain level of fat mass, adipokine secretion has ______________ effect
- Above a certain level of fat mass (obesity), adipokines are more likely to promote ____________ and ________
- a health promoting maintaining
- low-grade inflammation and disease
define: leptin
Leptin: AKA fullness hormone; adipokine that acts on the brain’s hypothalamus to promote satiety (fullness)
Fill in the blank: when our fat cells get larger, more leptin is released, decreasing ______ and promoting an ____ _____
- appetite
- energy deficit
Many individuals with obesity are leptin resistant; what does this mean?
hypothalamus does not respond to leptin and promote the satiety (fullness) effect
The ______ declared obesity a disease in ____. What makes obesity a disease?
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
The physical affects of obesity are categorizes into what 2 types?
- sick fat disease
- fat mass disease
define: sick fat disease
1 category of the physical affects of obesity
- adipokine secretion shifts to promote chronic low-grade inflammation
- type 2 diabetes, cardiovascular disease, certain cancers, fatty liver
define: fat mass disease
1 category of the physical affects of obesity
- added weight promotes biomechanical and structural challenges
- osteoarthritis, joint pain, sleep apnea, tissue friction
What is the evidence for the link between genetics and obesity
- Identical twins have a stronger BMI correlation than fraternal twins
- Identical twins gained similar amount of weight when overfed
- Body size and shape usually similar to our parents
- ~100 mutations associated with being common in obese individuals
- Mainly found around genes associated with appetite
What does it mean when people say obesity is polygenetic?
caused by multiple gene mutations
define: foresight model
Foresight model: obesity is caused by a multitude of factors such as social psychology, food production, food consumption, individual psychology, physiology, individual physical activity, environment
define: appetite
Appetite: drive to consume food
define: hunger
Hunger: physiological need to consume food
define: satiation
Satiation: feeling of fullness and satisfaction
define: satiety
Satiety: After a meal has been consumed, the feeling of fullness that determines the length of time before the desire to eat returns. Our appetite and satiety centers are found within the brain’s hypothalamus
define: obesogenic environment
Obesogenic environment: environment with an abundance of food that promote a constant stream of signals to provoke high energy consumption
Why do we sometimes eat to cope with something going on in our life?
- food has a rewarding effect on the brain
What is the main controllable factor that affects energy expenditure
physical activity
Fill in the blank: only ___ of Canadians meet the new recommendations for physical activity; what are the new recommendations for physical activity
- 15%
- 150 minutes of moderate to vigorous physical activity per week, accumulated in 10 minute bouts
Obese individuals are more likely to have what in their colon?
- firmicutes: These bacteria are better at harvesting energy from food, increasing energy intake
What is the gut brain axis?
- communication between microbiota and brain which may affect appetite and can increase obesity risk
What are the key appetite hormones? Where do they come from and what do they signal? Where do they all go?
- Adipose tissue → leptin → satiety signal
- Stomach → ghrelin → hunger signal
- Small intestine → GLP-1 → satiety signal
- All go to hypothalamus
define: neuropeptide Y
Neuropeptide Y: promotes feeding and energy storage
define: ghrelin
Ghrelin: Levels vary throughout the day, promotes appetite at certain times of day, its levels increase when sleep is compromised
define: peptide YY
Peptide YY: Reduces appetite after a meal
define: lipoprotein lipase (LPL)
Lipoprotein lipase (LPL): enzyme on adipocytes that captures triglycerides and promotes fat storage; the more fat cells you have, the more LPL you have
When do LPL levels increase?
- increase after weight loss adding to the difficulty of keeping weight off
Where are the sites of greatest LPL activity for women and men?
- women: breasts, hips, thighs
- men: abdomen
Define: body composition
Body composition: proportion of fat mass vs lean mass on the body
Define: visceral fat
Visceral fat is found around organs; Visceral adiposity is associated with higher disease risk
Define: subcutaneous fat
Subcutaneous fat is found under the skin
What are the gold standards for measuring body composition (2)?
- DEXA: low dose x ray that scans the body in 2 planes; body images to determine body composition
- air/water displacement
List some ways to measure body composition
- Skin folds
- Bioelectrical impedance
- BMI (weight in kg/ height in m squared)
- Waist circumference
What is waist circumference used in combination with and why?
Used in combination with BMI
If BMI > 30 and waist circumference is above a threshold = obesity, higher health risk
Male threshold: 102 cm
Female threshold: 88 cm
What is the key concept with weight loss?
- consistent energy deficit
1lb fat = ? kcal of stored energy?
3500 kcal
Losing 1lb of fat in a week requires ? kcal/day deficit
500
A reduction of weight of about 5-15% is associated with what?
a reduced risk of disease
What is the recommended weight loss rate? Why?
- 5lb-2lb a week
- fast weight drop is associated with weight regain
What does the national weight control registry show?
- Database of people who have lost 30+lb and kept them off for at least one year
- characteristics of weight loss maintainers
What are some characteristics of weight loss maintainers?
- modified food intake
- increased physical activity
- ate breakfast regularly
- weighed themselves regularly
- exercise an hour/day
- had a trigger for weight loss
What is the most commonly reported type of physical activity?
walking
What are some ways to control hunger?
- Whole foods, protein, fibre, volume rich foods, eating slowly, eating smaller meals more often
When is willpower at the lowest?
- at the end of the day
What are some examples of skill power
- laying clothes out the night before
- preparing food in advance so you have ready to eat healthy choices
- packing a gym bag and bringing it to school/work
- plan out meals in advance
- make exercise dates with friends
- eat mindfully
- minimize temptations in the immediate environment
- develop a distraction plan to deal with cravings
- keep healthy food options in sight to provoke consumption
How many minutes of exercise per week:
- maintains and improves health
- prevents weight gain
- promotes clinically significant weight loss
- prevents weight gain following weight loss
- 150 min/week
- 150-250 min/week
- > 250 min/week
- 200-300 min/week
define: self-efficacy
Self-efficacy: belief in our ability to achieve a certain task
Why do so many people put weight back on once lost?
- 10% decrease in body weight is associated with 20-25% decrease in energy expenditure
- weight reducers have lower satiety
- decreased thyroid hormones, leptin
- increase in fat storing enzyme lipoprotein lipase
- fat cells shrink when weight is loss but they don’t go away
- formerly obese individuals require 300-400 kcal less per day to maintain same weight as a person who never gained weight
Describe the negative feedback loop for fad diets
- fad diet
- quick weight loss
- physical and psychological changes
- inability to maintain diet
- weight regain
- weight dissatisfaction
What is 1 exercise strategy to gain weight and 1 food strategy to gain weight?
- Muscle building exercises is the best way to increase lean body mass
- consume more healthy fats and proteins like: nut butters, nuts, avocados, dried fruits
What are some medicines (3) for obesity?
- Orlistat: blocks lipase activity in the small intestine for decreased fat absorption and caloric intake decrease
- Liraglutide: increases the activity of GLP-1 and promotes satiety
- Naltrexone/Bupropion: reduces food cravings by altering the reward circuit in the brain that drives food-seeking behaviours
Describe bariatric surgery
- surgery of the stomach for weight loss. removing a portion of the stomach; sectioning and connecting only a small portion of the stomach to the small intestine; placing a band around the stomach to encourage slower eating
What are some risk factors for eating disorders
Risk factors for eating disorders: genetics, female gender, socio-cultural factors, personality, history of sexual/physical abuse
Define: binge eating
Binge eating: loss of control eating; occurs in bulimia, binge eating disorder, and anorexia
Define: binge eating disorder
Binge eating disorder: binge eating without compensation; promotes obesity
Most common eating disorder
binge eating disorder
What are some risk factors for binge eating disorder?
Risk factors include: frequent dieting, inability to interpret hunger/satiety signals
Define: bulimia nervosa
Bulimia nervosa: binge eating episode and compensation; vomiting, excessive exercise, laxatives
Bulimia nervosa risk factors
- Preoccupation with food
- Distorted perceptions around body weight
- Depression
- Frequent dieting increases risk
What is night eating syndrome
- abnormal increase of food intake at night
- > 25% of calories consumed after dinner
- lack of morning hunger
- insomnia
Define: orthorexia nervosa
orthorexia nervosa: an obsession with eating healthy that has negative psychological implications
What are some signs of orthorexia nervosa
- compulsively checking nutrition labels
- cutting out foods, nutrients, etc.
- limiting food intake to a narrow range of foods
What is the treatment for eating disorders
- diagnosis by a health care professional
- psychological treatment (CBT)
- medication maybe
