Energy Balance and Weight Control Flashcards
What is energy balance?
the relationship between energy intake and energy expenditure
positive energy balance
more calories in than calories burned=weight gain
negative energy balance
more calories burned than consumed=weight loss
energy in
carbohydrates, proteins, fats, alcohol
energy out
BMR, thermic effect of food, physical activity (and thermoregulation)
basal metabolism
the minimum amount of energy your body expends to keep you alive in a resting state.
What percentage of energy expenditure is BMR in a sedentary person?
60-70%
RMR
Resting Metabolism Rate-if the person is not fasting or completely rested this value is used instead. Typically higher than BMR (6%).
What percentage of energy expenditure does physical activity require
1/3-1/2 depending on level of activity
Which component of energy expenditure do we have the most control over?
Physical activity
Do heavier or lighter people burn more calories?
heavier people because they have to move more mass
Thermic Effect of Food
the energy the body uses to digest absorb, transport, store, and metabolize the nutrients consumed in the diet
What percentage of energy expenditure is TEF?
5-10%
Which macronutrient has the greatest TEF?
Protein (not much energy needed to transfer fat to adipose)
Factors that effect BMR
Greater muscle mass increases, Larger body surface area increases, smaller will lower, Male gender, Body temperature (fever or cold raises), Higher than normal secretions of thyroid hormones, Release of hormones (especially pre-menstrual), Growth stages of the life cycle (childhood/adolescence/pregnancy), Caffeine and tobacco use, Recent exercise, Aging after 30 years, Starvation will decrease BMR by about 10-20%, BMR is lowest when sleeping
Variables required to calculate energy estimation requirements
height, weight, age, gender, physical activity level,
Estimated Energy Requirements
standardized equations developed by the Food and Nutrition Board. Based on doubly labeled water and specific calculations for men, women, children, pregnant and lactating women, and teenagers
Components of body weight
BMI, body composition, distribution of fat, weight related medical conditions
BMI
Body Mass Index = weight (kg)/height (m)^2
Limitations with BMI
does not account for muscle mass; not readily applicable to those under 5 feet, children and adolescents, frail elderly, and pregnant and lactating women.
Weight status as defined by BMI
Underweight 30
body weight
fat + lean tissue (includes water)
ideal fat ratios in men and women
men= 8-24% females= 21-35%
fat fold measures (using calipers)
pinching different areas of body fat, very imprecise
hydrodensitometry
under water weighing- taking measurements in water to subtract out fat, fat is less dense then water
bioelectrical impedence
Fat is more resistant to electrical current. Lean tissue has electrolyte-containing fluids
Air displacement plethysmography (BodPod):
determines the amount of displaced air
Dual energy X-ray absorptiometry (DEXA)
GOLD STANDARD, distinguishes between fat, lean muscle, and bone
Central Obesity
more often related to cardiovascular disease, hypertension, and type 2 diabetes. Instead of emptying fat directly into general circulation, fat is released directly to the liver which interferes with the liver’s ability to clear insulin and alters lipoprotein metabolism
consequences of central obesity
Increased inflammation, insulin resistance, blood clotting, and blood vessel constriction
minimum measurement for adverse health effects with android obesity
men: 40 inches
women: 35
Medical issues associated with central obesity
heart disease, stroke, diabetes, hypertension and some cancers, sleep apnea, osteoarthritis, gall bladder disease and pregnancy complications
Issues associated with being underweight
Unable to preserve lean tissue during wasting disease, medical stresses, Menstrual irregularities, infertility in women, Osteoporosis, bone fractures
Prevelance of overweight and obesity in American adults
2/3 of Americans
Hyperplasia
increased number of cells
hypertrophy
increased cell size
when does the number of cells in body increase substantially?
childhood, adolescence, pregnancy
What is the result of adipocytes increasing in size and number?
Obesity
LPL
Lipoprotein Lipase: promotes triglyceride storage in fat cells, the more fat cells the higher the LPL activity, loss of body fat increases production of LPL
Do fad diets work?
any time you restrict calories you will lose weight, but is it sustainable?
Aspects of fad diets
offer exaggerated claims, false theories and hope, many are nutritionally inadequate
consequence of fad diets
headache, nausea, death
Weight loss surgery
gastroplasty: stomach reduced from 1 L to 30 mL; must have BMI over 40, no history of alcoholism or psychiatric disorders
Types of gastroplasty
gastric bypass, gastric banding, gastric sleeve
Pharmacotherapy
must have BMI over 30 (or greater than 27 if medical condition exists); no drug works without weight loss triad
Specific types of pharmacotherapy
Amphetamine-like: stimulates CNS
Sibutramine: works on NTs, reduces hunger
Orlistat: lipase inhibitor
Weight Loss Triad
health eating, physical activity, behavior change
Effects of increased physical activity
↑ energy expenditure ↑ metabolism Improves body composition Improves appetite control Psychological benefits
Aspects of behavior change
Chain-breaking Stimulus control Cognitive restructuring Contingency management Self-monitoring
Risks of yo-yo dieting
↑Risk of premature death ↑Risk of chronic disease Upper body fat deposition Possibly lower HDL Eroded self esteem
What does it take to lose a pound
1 lb= 3500 calories (decrease intake by 500-1000 kcal per day to lose 1-2 lbs per week);
