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Obesity, Diabetes, and
Physical Activity
CHAPTER 22 Overview
• Obesity
– Terminology
– Prevalence
– Control of body weight
– Etiology
– Health problems
– Treatment
– Physical activity
• Diabetes
– Terminology
– Prevalence
– Etiology
– Health problems
– Treatment
– Physical activity
Obesity:
Terminology and Classification
• Overweight
– Body weight exceeds standard weight for given
height and frame size
– Not precise terminology
– Does not account for body composition
• Obesity
– Excessive body fat (men >25%, women >35%)
– Borderline obese: men 20 to 25%, women 30 to
35%
Obesity:
Terminology and Classification
• Body mass index (BMI)
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Body weight in kilograms/(height in m)2
Most widely used standard for obesity classification
Does not account for body composition
Overweight: 25.0 to 29.9 kg/m2
Obese: 30.0+ kg/m2
• BMI classification cut points change for
difference races and ethnicities
Table 22.2
Obesity:
Prevalence in the United States
• Prevalence  dramatically since ~1980
– Prevalence of overweight has not changed much
– Obesity continues to increase
• More prevalent in some races and
ethnicities
– Mexican-American men
– Black women
• Increasing prevalence in children and teens
Figure 22.1a
Figure 22.1b
Figure 22.1c
Figure 22.2
Figure 22.3
Obesity:
Prevalence in the United States
• With age: fat mass , lean body mass 
– Over age 25, average person gains ~0.7 to 1 lb per
year
– Up to 33 extra lb by age 55
• Will have significant effect on health care
– Earlier onset of obesity
– Increasing rates of obesity
– Earlier onset of obesity-related diseases
Obesity:
Worldwide Prevalence
• Increases in obesity not unique to United
States
– Canada, Australia, Europe have seen increases to a
lesser degree
– Available data vary
– Most recent studies show obesity spreading to all
regions of the world
Table 22.3
Obesity:
Control of Body Weight
• Body usually carefully balances kilocalorie
intake and expenditure
– Gain of 1 lb/year represents imbalance of 3,111 kcal
per year
– Body can balance to within 9 kcal per day
• Body may regulate around set point using
– Resting metabolic rate (RMR)
– Thermal effect of meals (TEM)
– Thermal effect of activity (TEA)
Obesity:
Control of Body Weight
• RMR
– Body’s metabolic rate in the early morning
– 60 to 75% of total energy expenditure
• TEM
– Energy expended to digest, store nutrients, etc.
– 10% of total energy expenditure
– May be defective in obese individuals
Obesity:
Control of Body Weight
• TEA
– Energy expended to accomplish activities
– 15 to 30% of total energy expenditure
• Balance of RMR, TEM, TEA
– Helps body adapt to  or  kilocalorie intake
– Controlled by sympathetic nervous system
– Key for maintaining weight around set point
Figure 22.4
Obesity:
Control of Body Weight
• Set point regulation versus weight gain
– Diet composition alters set point
– Physical activity alters set point
– High-fat diets usually  overfeeding
• Other factors
– Larger portions/restaurant supersizing
– Higher fat consumption
– More eating away from home
Obesity:
Etiology
• Physiological factors
– Heredity/genetics
– Hormonal imbalances
– Altered basic homeostatic mechanisms
• Lifestyle factors
– Cultural habits
– Inadequate physical activity
– Improper diets
Figure 22.5
Obesity:
Health Problems
• Morbidity: presence or rate of disease
• Mortality: death from disease
• Obesity and overweight   mortality
• Major increased risk: BMI >35
Figure 22.6
Obesity:
Health Problems
• Obesity and overweight associated with
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Cardiovascular disease
Type 2 diabetes
Cancer (endometrial, breast, colon)
Liver, gallbladder disease
Osteoarthritis
Sleep apnea
• Metabolic syndrome rate parallels obesity
Obesity:
Genetic Versus Lifestyle Effects
• Pima Indians: study in genetics versus
lifestyle
• Native lifestyle  lean and healthy
• Western diet/lifestyle  high rates of
obesity
– Men: 64%
– Women: 75%
• Obesity often accompanied by diabetes
– Men: 34%
– Women: 41%
Obesity:
Genetic Versus Lifestyle Effects
Obesity:
Health Problems
• Changes in normal body function
– Vary with individual
– Vary with degree of obesity
• Lethargy
• Polycythemia
• Low blood O2/high blood CO2
• Clotting, heart failure
Obesity:
Health Problems
• Body fat distribution: disease risk factor
– Upper-body (android) obesity (men)
– Lower-body (gynoid) obesity (women)
• Waist:hip girth ratio and visceral fat index
identify fat distribution
• Android obesity  higher risk for
– Cardiovascular disease
– Elevated blood lipids
– Diabetes
Figure 22.7
Figure 22.8a
Figure 22.8b-c
Obesity:
Health Problems
• Exacerbates existing diseases
• Weight loss reduces severity of
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Angina pectoris
Hypertension
Congestive heart disease
Heart attack recurrence
Varicose veins
Diabetes
Orthopedic problems
Obesity:
Health Problems
• Emotional and psychological factors
– Can help cause obesity
– Can be exacerbated by obesity
• Obesity = social stigma
– Media glamorize thin people
– But norms may shift as obesity becomes more
common
Obesity:
General Treatment
• Weight loss = kilocalorie intake < kilocalorie
expenditure
– Oversimplification
– Weight loss treatment multifactorial
• Loss not to exceed 1 to 2 lb per week
– Weight loss a long-term project
– Maintain balanced diet with caloric deficit
– Reduce intake of fat and simple sugars
Obesity:
General Treatment
• Hormone treatments
– Decrease appetite
– Increase RMR
– Serious side effects, life threatening
• Surgical treatments
– Intestinal bypass
– Gastric banding or bypass
– Reserved for most extreme, serious cases
Obesity:
General Treatment
• Behavior modification: change in eating
patterns or habits. Examples:
– Can only eat in one location
– No snacking
– No second helpings
• Appealing, simple weight loss approach
Obesity: Role of Physical Activity
in Weight Control
• Overeating and inactivity: major causes of
obesity
• Kilocalorie restriction and exercise best
treatments
• Exercise alters body composition
– Significant long-term kilocalorie deficit
– Significant long-term fat loss
• EPOC   postexercise metabolism
Obesity: Role of Physical Activity
in Weight Control
• Body mass and composition changes with
exercise
–  Total weight
–  Fat mass, percent body fat
– Maintained or  FFM
• Changes long term (6-12 months)
Table 22.4
Obesity: Role of Physical Activity
in Weight Control
• Both aerobic and resistance training 
weight loss
– Exercise important aspect of weight loss
– Must combine exercise + kilocalorie restriction
– Decrease rate of visceral fat accumulation
• Energy balance equation
– Kilocalorie intake – kilocalories excreted = (RMR +
TEM + TEA)
– Helps clarify weight loss mechanisms
Obesity: Role of Physical Activity
in Weight Control
• Exercise effects on appetite
– Leads to appetite suppression in male animals
– Leads to no change or  intake in female animals
– Less activity ≠ less food intake
• Causes for appetite suppression
– Higher circulating catecholamines
– Higher body temperature
Obesity: Role of Physical Activity
in Weight Control
• Exercise effects on RMR
– May increase with training
– Resistance training of interest (RMR related to FFM)
• Exercise effects on TEM
– Pre- and postmeal exercise   TEM
– Chronic exercise training  inconclusive
• Exercise effects on fat mobilization
– During exercise, FFA mobilization 
– Possible causes: hGH, sympathetic stimulation,
catecholamines
Obesity: Role of Physical Activity
in Weight Control
• Spot reduction a myth
– Local exercise ≠ local fat loss
– Exercise draws on all fat stores
– Local exercise  local muscle development
• Spot reduction studies
– Tennis: dominant versus nondominant arms
– Intense sit-up training program
Obesity: Role of Physical Activity
in Weight Control
• Low-intensity aerobics and weight loss
– High intensity   percent energy from CHO
oxidation
– Low intensity   percent energy from fat oxidation
– Low intensity  no change in total fat kilocalories
expended
– Low intensity   in total kilocalories expended
• Fatmax zone
– Zone where fat oxidation rates near peak
– 55 to 72% VO2max
Table 22.5
Figure 22.9
Obesity: Role of Physical Activity
in Weight Control
• Exercise gimmicks ineffective. Examples:
– Mark II Bust Developer
– Astro-Trimmer Exercise Belt
– Slim-Skins Vacuum Pants
• Reality: exercise and weight loss require
work
Obesity: Physical Activity
and Health Risk Reduction
• Exercise   risk of disease mortality
– Irrespective of weight loss
– Good news for those who struggle with weight loss
• Active lifestyle and fitness more important
Diabetes:
Terminology and Classification
• Diabetes mellitus
– Hyperglycemia
– Insulin insufficiency and/or resistance
• Type 1
• Type 2
• Gestational
• Prediabetes
Diabetes:
Terminology and Classification
• Type 1 diabetes
– Autoimmune (b-cells destroyed, no insulin)
– Insulin-dependent diabetes mellitus (IDDM)
– 5 to 10% of all diabetes cases
• Type 2 diabetes
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Loss of insulin sensitivity (insulin resistance)
Non-insulin-dependent diabetes mellitus (NIDDM)
90 to 95% of all diabetes cases
Term adult onset no longer correct
Diabetes:
Terminology and Classification
• Gestational diabetes
– Develops in pregnant women
– 4% of pregnancies, causes complications
• Prediabetes
– Predictor of full-blown diabetes
– Impaired fasting glucose or glucose tolerance
• Glucose tolerance test: diagnostic test
– Oral
– Intravenous
Diabetes:
Terminology and Classification
• Signs of type 1 diabetes
– Excessive urination, thirst
– Weight loss, extreme hunger
– Fatigue, irritability
• Signs of type 2 diabetes
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Any type 1 symptom
Persistent infections, sores
Vision changes
Tingling, numbness in limbs
Diabetes:
Prevalence
• 17 million people diagnosed
• 7 million people undiagnosed
• 57 million people prediabetic
• 50% increase from 1990 to 2005
• Prevalence (diagnosed) varies by group:
Black 11.8%, Hispanic 10.4%, Asian
American 7.5%, White 6.6%
Diabetes:
Etiology
• Type 1 diabetes
– Pancreatic b-cells destroyed
– Cause may be autoimmune, viral infection,
degeneration
– Sudden onset in childhood, young adulthood
• Type 2 diabetes
– Gradual onset (children and adults)
– Impaired insulin secretion, action, responsiveness
– Obesity major factor
– b-cells, target cells less responsive
Diabetes:
Health Problems
• Cardiovascular disease (all forms)
• Kidney disease
• Neural disease
• Eye disorders (blindness)
• Dental disease
• Amputations
Diabetes:
General Treatment
• Type 1 diabetes
– Insulin administration
– Diet
– Exercise
• Type 2 diabetes
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Weight loss
Diet
Exercise
Recently developed drugs
Type 1 Diabetes:
Role of Physical Activity
• Exercise complicates glycemic control
– Hypoglycemia a risk
– Can lead to unacceptable plasma glucose
fluctuations
– Requires careful monitoring
• Monitor foot sensation, healing
• Helps reduce risk of coronary, cerebral, and
peripheral arterial diseases
Type 2 Diabetes:
Role of Physical Activity
• Exercise enhances insulin sensitivity
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Muscle contraction mimics insulin action
Lowers blood glucose
Decreases insulin requirement
Short-term (72 h) effect
• Combination of resistance and aerobic
training may be optimal