Final - Exercise and Weight Control/Obesity Flashcards
obesity
excess accumulation of body fat
final common pathway is chronic energy imbalance and energy intake exceeds energy expenditure
BMI and obesity classification
20 - 24.9: desirable range for men and women
25 - 29.9: Grade 1 obesity (overweight)
30 - 40: Grade 2 obesity
> 40: grade 3 obesity
obesity increases incidence of:
- coronary heart disease
- gallbladder stones
- hypertension, stroke
- cancer –> post menopausal breast, colon, kidney, endometriosis
- OA
- Type II diabetes/ glucose intolerance
- infertility
at 30- 35 BMI, survival is reduced by
2 to 4 years
at 40- 45 BMI, survival is reduced by
8-10 years
comparable to smoking
weight change and relative risk
even if weight remains in “healthy” range, an increase in body weight of > 10 since early 20’s increases risk of developing obesity- associated disease
regional fat distribution and health risk
- where the fat resides, independent of total stored fat, affects the health risk of obesity
- waist to hip ratios and waist circumferences –> increased health risk from abdominal (visceral) storage rather than hip/buttocks
current guidelines for waist circumference and risk for men
high risk: 100 - 120 cm
very high risk: >120 cm
current guidelines for waist circumference and risk for women
- higher risk: 90-109
- very high risk: >110 cm
increased health risk with abdominal (visceral) fat storage
- risk may be related to metabolically active state of this storage depot
- greater waist girth associated with higher risk of mortality regardless of BMI
high visceral fat is associated with:
- adverse lipid profile
- higher insulin/ insulin resistance
- hypertension
- left ventricular hypertrophy
- increased risk for endometrial and colorectal cancers
Energy balance =
energy intake - energy expenditure
what is normal physiologic response to an energy intake > energy expenditure
lipid storage
1 lb (0.45 kg of fat) = how many kcal?
3500
what factors affect intake of energy
- total energy intake, energy density and diet composition, timing and composition of diet relative to physical activity, current body weight and composition
what factors affect expenditure of energy?
- resting metabolic rate
- ADL/level of sedentary behavior
- metabolic cost of digestion and metabolism
- amount, type, timing, intensity of physical activity
- current body weight and composition
- thermogenesis
Energy balance:
- interaction of metabolic, neuronal, hormonal, and physiological factors
- environment, behavior and lifestyle factors
- epigenetic and genetics
what does energy balance ultimately influence?
weight, body composition, and overall health
obesity: interaction between genes and environment
- genetics: about 25% of inter-individual body fat variability is inherited
- culture: about 30% of variability due to environmental, cultural, learned
what is susceptibility to obesity affected by?
- genetic factors
- but environment determines the phenotypic expression of whether or not obesity occurs
obesity prevalence increases when cultures adopt:
- higher fat, highly energy/dense diets (western)
- change in physical activity
- other cultural and behavioral factors
how does reduced physical activity affect obesity?
- often an inverse relationship between daily physical activity and level of body fat (TV watching is a strong predictor of future obesity in children)
- obese individuals do not necessarily have a greater absolute caloric intake than non-obese controls, they just move less
how many extra kcals/day could obese sedentary individuals burn if they matched the non-exercise activity of leaner folks?
about 350 kcal
as far as food goes, studies in active humans suggest that regular exercise helps regulate what?
appetite
- in other words, improve the matching of intake to expenditure
in sedentary and/or obese population, what does regular exercise result in
net loss of weight as energy intake did not keep up with the new level of energy expenditure –> a net suppression of appetite (shocking)
negative side of exercise and food intake
- if you have been regularly active then become sedentary, food intake is slow to decrease to match the decrease in expenditure –> then ya get tubby tubs
what does exercise as a part of a weight loss program do?
- increases daily energy expenditure
- improves weight loss when added to a moderate caloric restriction program
what is important regarding exercise as a part of weight loss program?
the total amount of energy expended per day (intensity x duration)
difference between ACSMs definition of weight maintenance and change in body weight
- weight maintenance: <3% change
- clinically signifiant change in body weight: >5% change
how much physical activity for weight loss?
- work up to 300-500 kcal/day (minimum of 150 min/week)
- BEST results with 300 min/week, >2000 kcal/week of mod and 150 min/week of vigorous activity
when initiating physical activity for weight loss, what intensity should you start with?
moderate
40-60% VO2R
what exercise progression can overweight and obese adults benefit from?
- progression from 250-300 min/week or 50-60 min for 5 days/week (moderate to vigorous intensity
- for some individuals, progression to 60-90 mins of daily moderate exercise may be necessary
- intermittent activity ok
how much physical activity prevents weight regain after weight loss?
- scare evidence for specific recommendations
- suggestions is 250-300 min/week
- more like prevention of weight gain guidelines than minimum guidelines for weight loss
metabolic adaptation to weight loss
“long term weight loss requires vigilant combat against persistent metabolic adaptation that acts to proportionally counter ongoing efforts to reduce body weight”
resistance training will not:
- promote clinically significant weight loss
- add to weight loss when combines with diet restriction
resistance training increases:
- fat free mass when used along
what is resistance training more likely to do?
attenuate to or prevent loss of fat free mass (rather than increase fat-free mass) when combined with diet restriction
when might resistance training increase fat loss?
when combined with aerobic training compared to resistance training alone
health benefits of resistance training
- improved muscular endurance/ strength
- increase HDL, insulin sensitivity
- decrease LDL and triglycerides
- reduce blood pressure
other health benefits of physical activity other than changes in body composition
reduces or reverses:
- development of insulin resistance
- hyperinsulinemia
- dyslipidemia
- hypertension
- risk of developing type II diabetes
