Lecture 11 Flashcards
eating behaviour regulated by:
-signals and mechanisms that stimulate eating
-signals and mechanisms that to stop eating or lead to refrain from eating
hunger
-unpleasant sensation that signals for food
-4-6hrs after eating
-food has left stomach & nurtients absorbed
what triggers hunger
-triggered by contracting empty stomach and empty small intestine
-triggered by stomach hormone ghrelin
what drives eating
appetite
appetite
-phychological desire to eat
-experienced without hunger
-stimulated by sight & smell of food
-illness or stress may result in loss of appetite
factors affecting appetite
-hormones
-inborne appetites
-learned preferences
-habits
-social interactions
-disease states
-stimulates & drugs
-environement conditions
satiation
perception of fullness, determines how much food is eaten in a sitting, stretch receptors in stomach send signals to brain
satiety
suppresses hunger, determines length of time between meals, perception of fullness lingering after a meal
sensory specific satiety
-concept that we tend to get bored of a food as we eat it
-more variety=more likely we will increase overall consumption
buffet
people generally overeat
are hunger and satiety equal
no - hunger is stronger
Leptin
- a satiety hormone
–appetite-suppressing
-produced by adipose tissue in stomach
-travels to brain
-directly linked to appetite control & amount of body fat
gain of body fat stimulates
leptin production> reduces consumption resulting in fat loss>reduces leptin secretion increasing appetite
studies on glycemic index
some show low-glycemic index diet reduced or delayed hunger, other found opposite or no effect
of the energy yielding nutrients, which is the most satiating
protein
fat is known for its effect on
satiety
protein & fat trigger release of
intestinal hormone (CCK) that slows stomach emptying and prolongs feelings of fullness
fat
-weak effect on satiation
-provides a lot of kcals in small volume
Theories of metabolic causes of obesity
- Set point theory
- Fat cell number theory
- Thermogenesis 1: brown fat theory
set point theory
body somehow attempts to maintain a stable body weight
fat cell number theory
fat cells may increase faster in children who are obease contributing to obesity as adults
Thermogenesis 1: brown fat theory
brown fat (brown adipose tissue) has abundant energy wasting protiens. lean people have more brown fat, infants have abundant brown fat
genetics & obesity
-in rare cases, primary cause of obesity is genetic
-infleunce how body stores & uses energy
-genes not solely responsible
-adopted people have similar weight to birth parents
likelihood of genetic obesity
if a child has 1 parent obease, they are 40-70% likely to be obease
if genetics causes obesity, why have obesity rates skyrocketed when gene pool remains same
while genetics influences a persons tendency to become obease, lifestyle choices determine if tendency is realized
out side body potential causes of overweight/obesity
-people override signals of satiation/satiety
-variety
-in response to something (stress)
-food price/availability
-physical inactivity
obesogenic environment
all the factors surrounding a person that promote weight gain
for some people who are choosing to reduce their weight, a way to obtain a healthy body weight is to:
-maintain balanced diet
-engage in daily PA
-pharmalogical therapy
-physical intervention
what determines weight
the balance between energy intake & energy output determines whether you gain, lose or maintain body fat
slight/rapid change in weight
-body fluid content
-bone minerals
-muscle
-bladder or digestive tract contents
**change often correlates with time of day
weight gain
energy-yielding nutrients contribute to body fat stores
weight & protein
excess amino acids have their nitrogen removeed & are used for energy or converted to glucose or fat
weight & fat
fatty acids can be broken down for energy or converted to triglycerides and stores as body fat with great efficiency
weight & carbohydrates
excess sugars may be built up to glycogen & stores, used for energy or converted to fat & stored
fat cells
increase in size then in number (can increase almost indefinitely)
moderate vs rapid weight loss
-with insufficent food, body will draw from energy stores
-exercise & moderate calorie restriction will help body lose fat gradually
-moderate calorie restriction retains more lean tissue than severe fast
bodys first response to fasting
-less than a day into fast: liver glycogen stores are used up
-protein is broken down to meet brains need for glucose
bodys response to continued fasting
-breakdown of protein to protect cricual organs
-body converts fat into keytone bodies so the NS can adapt to using keytones
ketosis
-body takes partially broken down fat fragments & combines hen to form keytones
-after 10 days of fasting, most of the NS energy needs are met by keytone bodies
how long can a healthy person live totally deprived of food
6-8 weeks
short term fasting
body can handle it but no evidence for cleanse
negative effects fasting has on the body
-ketosis upsets acid base balance of blood, promoting mineral loss in urine
-24hrs of fasting causes SI lining to lose integrity
-deprevation leads to overeating
-degrades lean tissue
-decreases metabolic rate
ketogenic diet
-low carb, high protein
-large initial weight loss
-rapidly reverses when normal eating resumes
why does weight loss occur during keto diet
-water losses
-glycogen losses
limited variety
-protein rich food slow to prepare
-less dessert
body’s response to low carb diet
-similar to fasting response
-body breaks down fat & protein for energy & ketones for brain
DRI reccomendations for carbs
-130g/day RDA
-45-65% TOTAL energy intake from carbs (AMDR)
weight loss
-energy in must be less than energy out
-balanced diet safest long term
-increase PA
obesity management and weight loss research limitation
-weight loss intervention studies traditionally use BMI classification to define obesity rather than obesity
nutrition and weight loss recommendations for adults of all body sizes should:
-be personalized to meet individual values and preferences
-support dietary approach that is safe, effective, nutritionally adequate, culturally acceptable, and affordable
setting weight loss goals
-determine if loss or maintanence is most appropriate
-resonable (5-10% loss/year)
-set small goals for diet, PA and behaviour change
what to ensure when deciding to change behaviour
-nutrition changes need to be individualized
-realistic caloric intakes
caloric restriction
-caloric deficit can result in weight loss in short term but often not sustained
common caloric deficit recommendation
500kcal/day less or 3500kcal /week less
meal replacements
-shown to reduce body weight, waist circumfrence, BP and glycemic control
mediterranean diet
has shown weight loss improvements in glycemic control and blood lipids in people with T2D
macronutrient based approaches
no meaningful advantages of one macronutrient distribution over another have reliably been shown
balancing carbs, fats & protein
-carbs: 45-56% calorie intake
-fats: 30-35% calorie intake
-protein: 10-35% calorie intake
how to chose fats sensibly
-avoid trans fat
-limit saturated fat
-include enough to provide satiety but not oversupply calories
portion sizes
-large portions served in restaurants and packages
-ability to judge portion is important
-fat energy is DENSE
-generally at end of meal, same sensation of fullness regardless of portion size
-eating large portions of reduced calorie foods generally not beneficial
keeping records
-spot trends & areas of improvement
-measure waist circumfrence
alcohol
-strict limit intake
-abundant calories but no nutrients
-reduced inhibitions & sabotage healthy eating
-slows use of body fat & promote central body fat
ENergy density
-to lower caloric intake, reduce energy density
-leafy greens have low energy density
-fats high energy density
milk & milk products
-higher calcium intake, correlates with less adipose tissue
meal spacing
-people who eat small frequent meals are reported to be more successful at weight loss
-mild hunger should promote eating not appetite
-eating regularly before becoming very hungry can help
Intensive behaviour therapy/ Intensive lifestyle intervention program
-combine nutrition interventions and physical activity
-show sustained weight loss
-follow ups
-overall benefit
physical activity
-should increase if weight loss is a goal
-promotes fat loss, muscle retention, inhibit weight gain
-increase metabolism and reduce appetite
-helps follow diet
-improves BP, insulin resistance, heart & lung fitness
**independent of weight loss
Spot reducing
-exercising particular area cannot target fat removal from that area
-aerobic activity promotes release of abdominal fat
-improves strength & tone of muscle in areas
3 pillars to support medical nutrition therapy and physical activity
- Psychological intervention
- Pharmacotherapy
- Obesity surgery
psychological intervention
-behaviour change
surgery
-BMI 30-40 depedning on other factors
-meet criteria
-not always a cure for excess adiposity
-long term complications (vitamin & mineral deficiencies or psychological)
Gastric Banding
-provides restrictive method to weight loss
-adjustable silicone band is placed where esophagus and stomach meet
-adjusted with saline
Gastric bypass
-reestrictive malabsorptive method to weight loss because stomach and small inestine is reconfigured
-small stomach is created so it only holds a few bites of food
-intestines are cut and entire duodenum and part of jejunum are bypassed
Duodenal switch
-restrictive and malabsorptive method to weight loss
-stoamch and SI and reconfigured
-stomach reduction is less than bypass but more of the small intestine is bypassed
sleeve gastrectomy (gastric sleeve)
-restrictive approach
-long slender sleeve stapled
-other part of stomach removed
-stomach is banana sized
life long nutrition supplements for those with gastric bypass
-multivitamin
-B12
-Calcium citrate
-vitamins D
-Iron
-crushed/chewable/liquid in first 2 months
gastric bypass surgery diet
-clear fluids for a day
-full fluids for 10 days
-pureed diet
-4 tbsp per meal
-ensure adequate protein, liquid, vitamin and minerals
medications for obesity management
-more infrequent than other medications
-considered early
-not a quick fix
what happens if obesity medication stops
weight gain again
pharmacotherapy treatment targets
-weight loss
-improve health
-control cravings
-improve quality of life
criteria for prescription medication for obesity
BMI >30 or BMI>27 and obesity related complications
Sibutramine
-suppresses appetite by inhibiting serotonin uptake
-taken off market in 2010
-max weight loss achieved after 6 months and gained when therapy stopped
herbal products for obesity
-effectiveness and safety not proven
-natural does not mean safe
Ephedrine/Ephedra
health canada warns against unapproved products sold for:
- weight loss
-increased energy
-body-building
-euphoria
-side effects: stroke/death
dieters tea
-herbal laxatives containing senna, aloe, rhubarb root, cascara,castor oil or buckthorn
-cause temporary water loss
-nausea, vomitting, diarrhea, cramping, fainting
gimmicks
-steam baths and saunas do not melt fat (dehydrate you & result in water loss)
-brushes, sponges, wraps, creams & massages intended to move, burn or break up cellulite do not result in fat loss
key to weight maintence
-accepting it is a lifelong endeavour of healthy habits
-healthy balanced diet and exercise
canadas food guide focuses on
nutrition and eating patterns to promote health
weight gain
-underweight healthy person should not necessarily try to gain weight., just maintain
-PA to gain muscle & fat; strength training with high calorie diet
-diet alone for weight gain not ideal
-chose high energy dense foods
high energy dense foods
-peanut butter in place of lean meat
-avocado in place of cucmber
-olives instead of pickles
what should you avoid when trying to gain weight
tobacco - supresses appetite and makes taste buds & olfactory organs less sensitive
