ch 7 and 8

Healthy Weight and Body Composition

BODY COMPOSITION•Body composition is the ratio between fat and

fat-free mass

•Fat-free mass includes all tissues exclusive of fat (muscle, bone, organs, fluids)

•Essential fat is necessary for normal biological function

•Essential fat for men is 3% to 5% of total weight; it is 8% to 12% percent for women

MEASURING BODY COMPOSITION

•Height/weight tables do not reflect body composition and are poor instruments for weight-loss recommendations

•Body mass index (BMI) is the ratio of body weight in kilograms to height in meters squared

•People with BMIs of 25 to 29.9 are considered overweight; people with BMIs of 30 or higher are considered obese

TECHNIQUES

BMI-Body Mass Index

• Healthy weight is defined as a body mass index (BMI) equal to or no more than 18.5 and no more than 24.9

• Overweight is defined as having a BMI between 25 and 29.9

• Obesity is defined as having a very high amount of body fat in relation to lean body mass or a BMI or 30 or higher

• Adult obesity has grown from 13% in 1960 to 40% in 2012

• Children and adolescent ages 2-19 – 32% are obese

• 17% of children have a BMI of 30 or higher

• Americans are heavier because:

• Too little energy going out

• Too much energy going in

• America has become an obesogenic environment i.e. one that promotes increase food intake

• Bioelectrical impedance analysis

• uses a low-level, single-frequency electric current to measure body composition

• Skinfold measurements

• one of the most economical ways to measure body composition and, when performed by skilled technicians, correlate well with hydrostatic weighing

• Air-Displacement Plethysmography

• Uses air displacement rather than water displacement for assessing body composition by sitting in the Bod Pod

MORE TECHNIQUES

•Underwater weighing is one of the most accurate indirect measurement techniques

•People with more muscle mass weigh more in water than those with less

Hydrostatic Weighing

•Dual-Energy X-Ray Absorptiometry

•bone mineral density, quantification of fat, and lean tissue using very low exposures to radiation.

DEXA

ACHIEVING A HEALTHY WEIGHT

• At any given time, more than one-half of women and one-fourth of men are on a diet

•For some people the weight obsession can lead to serious body-image problems, including body dysmorphic disorder (BDD)

•The number of people who would benefit from a fat-loss program is at an all-time high

•Term weight loss should be replaced with the more specific term fat- loss

OBESITY AND OVERWEIGHT•Obesity is overfatness

•Obesity in men is defined as body fat equal to or greater than 25% of total body weight

•Obesity in women is defined as body fat equal to or greater than 35% of total body weigh

•Overweight is excessive weight for height and does not consider body composition

REGIONAL FAT DISTRIBUTION•Most women store fat in the hips,

buttocks, thighs, and breasts (gynoid fat)

•Most men store fat in the abdomen, lower back, chest, and nape of the neck (android fat)

•Intra-abdominal fat is stored deep in the abdominal cavity and carries a high risk for cardiovascular diseases

ADIPOSE CELL DEPOSITS

DEVELOPMENT OF OBESITY

• Obesity occurs when the 30 to 40 million adipose (fat) cells in the body increase in size (hypertrophy), number (hyperplasia), or both

• Gender differences in fat storage

• Males- upper half of body (android)

• Females- lower half of body (gynoid)

• Biological factors that influence obesity are age, metabolism, gender, disease, heredity, and set point

HEALTH ASPECTS OF OBESITY

• Coronary heart disease

• Stroke

• Hypertension

• LDL cholesterol

• Diabetes II

• Psychological distress

• Gallbladder disease

• Osteoarthritis • Sleep apnea • Some cancers

OBESITY TRENDS AMONG U.S. ADULTS

CAUSES OF OBESITY

• Biological Theories

• Age, metabolism, gender, disease, heredity and set point, the body internal signal for the level of fatness

• Two major biological explanations of obesity are heredity and set point

• Heredity influences both body weight and body shape

• Leptin – hormone made in fat cells by a gene call OB

• leptin signals brain to suppress appetite – if missing or not functioning brain does not get signal to stop eating

• The set point theory suggests that the body works to maintain a certain weight no matter what a person does

• Sometimes referred to as Defended Weight

•Weight that body strives to attain when not on a diet or participating in an exercise program – normal weight

•Body has internal set point for the weight it defends

• Physiological evidence to support the set point explanation

•As the energy intake is reduced, the blood concentration of thyroid hormone falls and the metabolic rate slow

BEHAVIORAL THEORIES

• Behavioral explanations of obesity include overeating, lack of exercise

• Overeating - consuming more calories than are required by the body

• Most experts view high dietary fat intake as the major factor in obesity

• Calories from fat appear to convert to body fat more readily than calories from carbohydrates and protein

• Portion size• Fat grams and low-carbohydrate diets are of less concern than the quantity of food eaten

OVEREATING AND INACTIVITY

• People cannot eat as much as they want to just because a food is fat free

• Modern conveniences and labor-saving devices have resulted in less physical activity

• A sedentary lifestyle is partially responsible for the obesity in America

• Physical exercise is vital for weight maintenance

INACTIVITY

• Hypokinesis – physical inactivity or sedentary lifestyle

• Some experts view lack of physical activity as the distinguishing factor that separates the obese from those of normal weight

• Exercise alone is not a major component in weight loss, but it is the most important component in weight gain

STRATEGIES FOR FAT LOSS• The loss of one pound of body fat requires a deficit of

3500 calories • A desirable long-term goal for losing weight is 1 to 2

pounds a week until 10% of total body weight is lost • A six-month maintenance program should follow weight

loss before losing more• Weight loss should be a combination of restricting

calories and increasing caloric expenditure

• the method of choice for most people to lose weight

•Only 5% of dieters successfully lose and maintain their weight loss for one year

•Weight cycling (yo-yo dieting) usually results in a greater weight gain following a loss period and increases the risk of death

Dieting

• Caloric intake should not drop below 1200 per day for women or 1500 per day for men

• Popular Diets

•Potentially hazardous

• Characteristics of fad diets

•Promote quick results;

• focus on eating one type of food or

• excluding an entire food group,

• rarely emphasize permanent lifestyle changes

• Low fat diets

•Americans are consuming fewer fat calories but more total calories and are getting heavier

• Very low calorie diets (VLCDs) have fewer than 800 calories a day and should be viewed as medical intervention

• Overcompensatory eating is when the consumption of low-fat foods leads to an increase in total calories

• Increases in portion sizes of foods in restaurants and in the grocery contribute to greater food consumption

• Diet drugs offer only a temporary solution and side effects can be deadly

• Bariatric surgery – surgery to reduce weight• Gastroplasty –limits stomach size

• Popular term – stomach stapling

• Several variations of gastroplasty

• Considered a treatment for those individuals whose BMI is 40 or greater • men 100 pounds overweight

• Women 80 pounds overweight

• Liposuction – surgical removal of fat tissue• Cosmetic procedure

Extreme Treatments

• Herbal remedies are unregulated and when taken in large, concentrated doses should be viewed as drugs

• The optimal approach to weight loss combines mild caloric restriction with regular physical activity

• Fasting and modified fasts can be harmful especially if done for a prolonged period of time

PHYSICAL ACTIVITY• Physical activity and dieting should yield a daily

caloric deficit of 500 calories

• 3500 caloric reduction to lose one pound of fat

• Exercise stimulates metabolism

•Metabolism affected by age, gender, nervous system activity, endocrine glands, nutrition, sleep, fever, climate & amount of muscle tissue

PHYSICAL ACTIVITY• Basal metabolic rate (BMR) is the energy required to

sustain life when the body is rested and fasting

• Persons who are deconditioned need to start slowly and progress gradually

• Increased muscle tissue raises BMR

• People who lose weight and keep it off almost always exercise daily

• Low intensity exercise burns more fat calories

GUIDELINES• To reduce risk of chronic diseases in adulthood: 30min of moderate

physical activity daily

• To prevent unhealthy weight gain in adulthood: 60 min of moderate to vigorous physical activity on most days

• To sustain weight loss in adulthood: 60min moderate daily physical activity

EATING DISORDERS• Anorexia nervosa

• the refusal to maintain minimally normal weight for age and height.

• characterized by the refusal to eat

• Bulimia nervosa • alternates bingeing with purging (Symptoms of disordered eating are also

serious

• Binge-eating disorder

• Consuming large amounts of food in one sitting

• Lack of control

• The Female Athlete Triad is common among young athletes

• Disordered eating, amenorrhea, osteoporosis

PRINCIPLES OF WEIGHT MANAGEMENT

• Avoiding an obsession with body weight

• Avoiding fad diets

• Avoiding fasting and restrictive dieting

• Avoiding volume eating

• Watching “hidden sugar”

• Developing a plan

• Set realistic goals

• Being physically active

• Making gradual lifestyle changes• Avoiding diet pills• Avoiding very-low calorie diets• Avoid fasting• Avoid skipping meals• Remember weight maintenance may be

more appropriate than weight loss• Consulting a nutritionist, physician, or

weight-loss program provider to help develop a plan