Lec 1- Energy Balance, Body Composition and Disease Flashcards
Energy balance (3)
Balanced weight= IN (energy consumed) = OUT (energy expended)
Weight gain= IN > OUT
Weight loss= IN < OUT
Sources of calories in (4)
1 g carbohydrate = 4kcal
1 g protein = 4 kcal
1 g fat = 9 kcal
1 g alcohol = 7 kcal
Sources of calories out (4)
- Basal metabolic rate (65%)
- Non-exercise thermogenesis (20%)
- Exercise thermogenesis (10%)
- Thermic effect of feeding (5%)
RER: Resting Energy Expenditure
-Amount of energy required by the body in the resting condition
-Measured under less restrictive conditions
-Fasted 3-4 hours
-Doesn’t need to be measured following sleep
-No exercise for 12 hours prior to test
- Typically 10% higher than BMR (less accurate)
BMR: Basal Metabolic Rate
-Amount of energy needed to maintain basic life metabolic processes at rest
-Measured under very restrictive conditions
-Overnight fast (12 hours)
-Measured in the morning following sleep
-No exercise for 24 hours prior to test
-Typically 10% lower than RER (more accurate)
Energy OUT: Factors that effect BMR (4)
-Sex
-Age
-Muscle
-FFM
Energy OUT: Thermic effect of food
-Reflects the energy cost (burned) during food digestion, absorption, and storage
Energy Out: Physical Activity
-Includes all exercises and non-exercises activities associated with daily living
-NEAT and EAT thermogenesis
Energy OUT: Non-exercise activity thermogenesis (NEAT)
-Portion of daily energy expenditure resulting from spontaneous physical activity that is not the result of voluntary exercise
*one of the most critical
-ex. strenuous work -> standing work -> seated work discretion to move-> seated work no option of moving -> seat bound
Energy Out: Exercise activity thermogenesis (EAT)
-Number of calories burned when engaging in purposeful exercise
-1-hour intense exercise ~800-1100 kCal
METs for Sports and Leisure Activities
-Metabolic Equivalent of Task (MET)= ratio of the rate of energy expended during an activity to the rate of energy expended at rest
-1 MET is the the amount of oxygen consumed while sitting at rest ~3.5 mL/kg/min
Moderate 4-6: gardening, dancing, softball, golf
Vigorous 6-8: hiking, weightlifting, downhill skiing, doubles tennis, ballet, backpacking, boxing, beach volleyball, basketball, singles tennis, rock climbing
Maximum 10: competitive soccer, martial arts
Energy IN has increased over time (3 reasons)
-24% in calorie intake since 1961
-62% of Canadian diet is processed and ready to eat foods
-bigger portion sizes
-declines in physical activity
PA on all cause mortality
All intensities of device measured physical activity, including light intensity, are associated with a substantially reduced risk of death in a dose-response manner
How does Canada Define Obesity?
“A progressive chronic disease characterized by abnormal or excessive fat accumulation that impairs health”.
-Associated with type 2 diabetes, high blood pressure, heart disease, stroke, arthritis, cancer and other health problems…
How do we measure obesity in Canada?
Body Mass Index (BMI) = universal definition of overweight and obesity
BMI= mass(kg) /height (m)^2
Underweight: <18.5
Normal weight: 18.5-24.9
Overweight: 25-29.9
Obese I: 30-34.9
Obese II: 35-39.9
Obese III: >40
*BMI not accurate of body composition (can have a lot more muscle and be fit but considered overweight or obese)
BMI Limitations (3)
- Body composition
- Fat distribution
- Ethnic groups of age
BMI and body fat % odds ratios (4)
-high BMI and high % body fat= high risk
-low BMI and high % body fat= high risk
-high BMI and low body fat= lower risk
-low BMI and low body fat= lowest
Methods for Measuring Body Composition- Direct Methods (3)
- MRI- high cost, ~10-45 mins, high skill required, moderate comfort, ~1.2% error
- CT- *same as MRI
- DEXA- high cost, ~30 mins, high skill required, moderate-high comfort, ~1.2% error
*these are most accurate methods, but most expensive
Methods for Measuring Body Composition- Indirect Methods (2 lab based and 2 field methods)
Lab based:
1. Hydrostatic Weighing- high cost, 30-60mins, high skill required, low comfort, 2.3-2.8% error
2. BodPod- high cost, ~10mins, medium skill required, moderate comfort, 2-3% error
Field Methods:
1. Skin folds- low cost, 10-30mins, high skill required, low comfort, 3-3.5% error
2. BIA- low cost, ~5mins, low skill required, high comfort, 3-3.5% error
Subcutaneous Adipose Tissue vs. Visceral AT
Subcutaneous
-Over 80% of total body fat
-Energy storage
-Adrenergic stimulation and endocrine regulation
Visceral:
-5-20% of total body fat
-Protects organs
-Secretes proinflammatory cytokines
Visceral Adipose Tissue and Health Risks
-Visceral obesity is associated with metabolic abnormalities that increase risk of type 2 diabetes and coronary heart disease
-Visceral adipocytes may mediate insulin resistance
*put on the most when you consume the most alcohol (Fatty acid liver disease)
*exercise and reduce calorie intake it will decrease the quickest
Men vs. Women obesity and risk
More men have obesity than women, and men tend to be at higher risk (increased VAT)
Men and VAT accumulation and central adiposity
-men have more visceral fat
*android obesity (apple)
Women and SAT accumulation and lower body fat accumulation
-women have more subcutaneous fat
*gynoid obesity (pear)
Is a calorie just a calorie?
In general, yes *for weight loss/management. Diets high in added sugar or other processed carbohydrates should have no special adverse effects of metabolism or body composition, after considering total calorie consumption.
So what is responsible?
1. Fat/alcohol?
2. Protein/ultraprocessed?
3. Carbohydrate?
Protein Intake and Thermogenesis
-Protein causes increased diet-induced thermogenesis
Conventional model of calories (overeating)
Overeating-> increased energy intake, with decreased e.e. -> increased circulating metabolic fuels (glucose and lipids) -> increased fat storage
Carbohydrate-Insulin Model
Hunger-> carbohydrate increased-> increased insulin secretion-> increased fat storage -> decreased circulating metabolic fuels -> increased energy intake and decreased e.e.
Reduced carb vs fat intake
- Only reduced carb diet decreased insulin secretion
- Only reduced carb diet increased fat oxidation
- More cumulative body fat loss with reduced fat
*carbohydrate-insulin model not supported - Only reduced carb decreases energy expenditure
Ultra-processed foods
Highly processed= decreased fibre
‘Ultra processed foods are those that contain ingredients predominantly found in industrial food manufacturing, such as hydrogenated oils, high fructose corn syrup, flavouring agents and emulsifiers’
*not necessarily fat or carbs that are driving weight gain/loss, could be type of foods (ultra processed and processed, decreased fibre, decreased appetite control
Ultra-processed diet paper results: *important
- Twenty inpatient adults received ultra-processed and unprocessed diets for 14 days each
- Diets were matched for calories, sugar, fat, fiber and macronutrients
- Ad libitum intake was 500 kcal more on the ultra processed diet
- Body weight changes were highly correlated with differences in energy intake
Summary
- Both increased carbohydrate and fat intake are driving weight gain
- Refined carbohydrate intake may accelerate weight gain
- A calorie is generally a calorie when it comes to weight loss
Decision to eat food is complex (4 factors)
-psychological and environmental factors
-initiation/termination of meals, size, composition, frequency
-lifestyle habits, drive to seek tasty foods, enjoyment, social
-physiological component: feeding and fasting
*obesogenic environment/society
Physiology of Energy Intake (4 aspects)
1) Afferent peripheral hormonal signalling- appetite (orexigenic) or satiety (anorexigenic)
2) Central integration
3) Efferent signalling
4) Behavioural change
Neurohormones (4 areas, 5 hormones)
- Stomach- Grehlin *orexigenic/appetite
- Intestine- PYY, GLP-1 *anorexigenic/satiety
- Pancreas- PP *anorexigenic/satiety
- Adipose Tissue- Leptin *anorexigenic/satiety
ARC Region= arcuate nucleus= all these sensory signals integrate
Neuropeptides (5)
Orexigenic: NPY, AgRP *signal for hunger
Anorexigenic: POMC-> a-MSH, CART *signal for not hungry
*neurohormones signal release of neuropeptides from ARC region of brain
Study on exercise and appetite
-Utilized exercise intensity and/or sodium bicarbonate supplementation to modulate endogenous lactate
-Data consistently demonstrates greater blood lactate accumulation is associated with greater suppression of grehlin and appetite
-Intense workouts leave you less hungry
-Investigations into other potential mechaniss (IL-6 and sex hormones) ongoing
