Ch21 The Role of Physical Activity in Weight Loss and Weight Loss Maintenance
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Transcript of Ch21 The Role of Physical Activity in Weight Loss and Weight Loss Maintenance
Ch21 The Role of Physical Activity in Weight Loss and Weight Loss Maintenance
Rosae Calvo11/01/13
Outline• Introduction
• Relationship between physical activity and weight changes
• Measurement of physical activity
• Methods and theories to initiate and maintain physical activity among overweight/obese
• Diversity issues in physical activity and weight loss
• Recommendations
• Activity
Introduction
• Weight management efforts in overweight/obese usually require calorie restriction in addition to physical activity
• Best predictor of sustained weight loss
• Prevents loss of lean body mass and helps to maintain energy balance
Relationship between physical activity & weight changes
• Energy balance – involves complex physical and behavioral mechanisms
Weight MaintenanceCaloriesBurned
Weight Gain
CaloriesEaten
Weight Loss
INTAKE EXPENDITURE
INTAKE
EXPENDITURE INTAKE
EXPENDITURE
Relationship between physical activity & weight changes
Energy intake
• Affected by biological, psychological, social, and developmental processes
125 kcal
95 kcal 152 kcal
Relationship between physical activity & weight changes
Energy expenditure = Basal metabolism + TEF + PA
• Basal Metabolism – energy required to sustain life at rest• Breathing, blood circulation, thermoregulation• 60-75% total daily energy expenditure in
sedentary adults• 1 kcal/kg weight/hour
• Calculate BEE for a 150lb and 400lb person
• Thermic effect of food• Digestion, absorption, nutrient storage• 10% total daily energy expenditure
Relationship between physical activity & weight changes
Sitting 90 kcal (1.0 MET)
Standing 110 kcal (1.2 MET)
Watering lawn 136 kcal (1.5 MET)
Mild stretching 228 kcal (2.5 MET)
Bicycling (<10mph) 364 kcal (4.0 MET)
Bicycling (stationary) 500 kcal (5.5 MET)
Weightlifting 546 kcal (6.0 MET)
Aerobic 590 kcal (6.5 MET)
Swimming, moderate 636 kcal (7.0 MET)
Running (5mph, 12 min/mi)
728 kcal (8.0 MET)
Circuit training 728 kcal (8.0 MET)
Swimming, vigorous 908 kcal (10.0 MET)
Energy Expenditure
• Activity thermogenesis – skeletal muscle activity• Voluntary and involuntary movements • Exercise-related activity and non-exercise
activity• 15-50% of total daily energy expenditure• Factors: occupation, leisure time PA,
households tasks, self-care activities
Table 21-1 Kcal expended per hour across activities for a 90 kg (198 lb) person
Difference between Physical Activity and exercise
• Physical activity: any movement that results in skeletal muscle contraction and increases in energy expenditure• Non-exercise activity thermogenesis (NEAT):
occupational tasks, standing, walking, talking, tapping, playing an instrument, shopping, etc.
• Exercise: planned, structured, and repetitive bodily movement with primary goal of improving/maintaining physical fitness
Difference between Physical Activity and exercise
NEAT vs. Exercise
• Data suggests NEAT contributes more to increased energy expenditure compared to structured exercise; consider a lifestyle approach rather than structured exercise
• One study showed NEAT is just as effective as exercise in improving blood lipid levels and blood pressure
• Weight-loss option for overweight/obese: Diet + NEAT
Effect of physical activity on weight
• Prevention of weight gain• Average weight gain: 1-2 lb/year• Prevented by expending ~100kcal through
physical activity per day or by reducing intake by ~100 kcal/day
• 15-30 min. of daily moderate-intensity activity may prevent weight gain• 1-1.5 miles of walking• 2000-3000 steps/day• Varies by the individual; genetic factors
may increase amount of work needed
Effect of physical activity on weight
• Initial weight loss for sedentary individuals• Scientific evidence suggests greater weight
loss is achieved through dieting or dieting + PA
• For sedentary/unfit individual, it is more feasible to tip the energy balance equation by reducing calorie intake
Effect of physical activity on weight
• Weight loss maintenance• Important for preventing weight regain, loss of
lean muscle mass, and for improving health• National Weight Control Registry (NWCR):
Duration and intensity levels associated with weight loss maintenance• Success linked with reduced calories and
reports of >1 hr of moderate-intensity activity daily
• Decreases in activity associated with weight regain
Effect of physical activity on weight
• Resistance training – e.g. weightlifting• Theory: Increase in fat-free mass results in
weight loss by increasing RMR• Reality: Preserves lean muscle mass in
dieters but does not maintain or increase RMR
• Benefits• Increase strength increases likelihood of
sustained exercise increase energy expenditure
• Maintains bone density
Measurement of physical activity
• Criterion methods – gold standard; expensive, inaccessible; rarely used in clinical settings• Doubly-labeled water – measures total
energy expenditure or metabolic rate; • Indirect calorimetry – determines energy
expenditure by measuring volume of expired air from lungs and analyzing oxygen-carbon dioxide content
Measurement of physical activity
• Objective methods• Pedometers – motion sensory that measures
steps taken while walking/running• Accelerometers – motion sensory that
provides an estimate of overall physical activity; sensitive to all body movement
• Heart rate monitors
Measurement of physical activity
• Subjective/Self-report methods – inexpensive, frequently used in epidemiological and intervention studies• Diaries• Interviews• Questionnaires
theories to initiate and maintain physical activity among overweight/obese
• Transtheoretical Model (TTM): individuals progress in a non-linear fashion through 5 stages when changing any health-related behavior
theories to initiate and maintain physical activity among overweight/obese
• Social cognitive theory: incorporates general strategies for progressing through stages of change; based on psychosocial, environmental, and behavioral factors • Increase confidence in ability to initiate and
maintain physical activity• SMART goals
• Focus on progress and reinforcement of successes
• Techniques: modeling, self-regulation strategies, develop social support
Specific, Measurable, Attainable, Relevant, Timely
theories to initiate and maintain physical activity among overweight/obese
• Health Belief Model – individuals will engage in physical activity if they perceive their sedentary lifestyle to be a health threat and if they believe that activity will be helpful in reducing that threat
theories to initiate and maintain physical activity among overweight/obese
• Theory of Planned Action – health behaviors are not only a function of health beliefs, but are also associated with other factors, such as attitude toward a health behavior, perception of social norms, self-efficacy, and locus of control
theories to initiate and maintain physical activity among overweight/obese
• Active Living Every Day (ALED) – promotes adoption and maintenance of physical activity among adults• Principles:
• Physical activity need not be strenuous or time-consuming to benefit health.
• People are more likely to become and stay physically active when taught appropriate lifestyle skills
Diversity issues in physical activity and weight loss:
Underserved populations
• Increased risk of obesity in racial/ethnic minority groups (African Americans, Hispanics)• Less likely to participate in weight loss
interventions, have weight loss success, be physically active
• More likely to consume a poorer diet
• Healthy People 2010 goal: Eliminate health disparities across gender, race/ethnicity, and geographic location
• Majority of studies based on the predominantly White population
Summary
• Weight gain prevention and weight loss maintenance involves increasing physical activity through increases in NEAT or structured exercise
• Need to shift from a “one-size-fits-all” approach to an individualized approach
• The amount of physical activity needed to achieve health benefits is less than the amount needed to achieve weight loss
Recommendations
• For optimal health benefits: 30 min/day moderate intensity, 5 days per week• Bouts of at least 10 min.• Resistance exercise twice a week
• For weight maintenance: 30-60 min/day
• For weight loss maintenance: 60-90 min/day
• For children: 1 hr/day of moderate to vigorous activity
• Resource: www.health.gov/paguidelines
Questions?
Activity: Based on the following motivational quotes, what do you think are some of the biggest misconceptions
about physical activity and weight loss?
Thank you!