Energy Balance and Body Composition Studying = 1 or 2 kcalories/minute

Energy Balance

Energy Balance Energy In: How is it measured? What controls it?

Food Composition Bomb calorimeter Calorie = the amount of energy necessary to raise a ml of water 1 degree. Food calories = kCalories

Food Composition Direct calorimetry vs. indirect calorimetry Actually burning food to measure calories versus measuring respiration Physiological fuel value How well the body can utilize the calories

Physiological Fuel Value

Food Intake Hunger: the feeling that motivates us to eat Appetite: sights, smells, thoughts that motivate us to eat. Satiation: feeling of fullness Satiety: the feeling that reminds us not to eat again.

Food Intake Regulation of intake Prompts eating; physiological desire Hunger Prompts eating; physiological desire Satiation Signals to stop eating Satiety Lack of hunger Appetite Psychological desire

Food Intake

Appetite Factors affecting appetite Hormones Inborn appetites Learned preferences, aversions, timings Customary eating habits Social interactions Some disease states Appetite stimulants, depressants, mood-altering drugs Environmental conditions

Food Intake Sustaining satiation and satiety lower-fat foods can be eaten in larger portions for the same number of kcalories

Energy Balance Energy Out: Where does it go?

Thermogenesis Thermogenesis is the term for expenditure of calories (or heat generation). There are four main types: Basal metabolic Exercise-induced Diet-induced Adaptive

Components of Energy Expenditure Basal metabolic rate (BMR) Energy to maintain body temperature, breathing, making new cells, heart beating, and kidney function. 2/3 of energy

How to estimate calories needed to meet BMR Men: body weight (lbs) times 11 Women: body weight (lbs) times 10 170 lb man X 11 = 1870 cals/day 135 lb woman X 10 = 1350 cals/day

Components of Energy Expenditure Exercise Induced

How to estimate calories needed to meet activity. Amount spent depends on activity level Inactive 30% of basal metabolism calories Average 50% of basal metabolism calories Active 75% of basal metabolism calories Example: if basal metabolism = 1500 Inactive person 1500 X .30 = 450 calories Average person 1500 X .50 = 750 calories Active person 1500 X .75 = 1125 calories

Components of Energy Expenditure Thermic effect of food (TEF) Energy of digestion 10% of calories are to digest the food "McStomachache, McGurgles, McGas"!

Components of Energy Expenditure Adaptive Thermogenesis Extreme reactions to the environment; cold, heat, overeating, starvation, trauma.

How many calories do you need? Total daily need for calories = Basal metabolic rate 1500 Activity (inactive) 450 Dietary thermogenesis 195 TOTAL = 2145 calories

Estimating Energy Requirements Gender Growth Age Body composition Body size

Estimating Energy Requirements Gender: women have lower BMR than men Growth: BMR is higher in growth and pregnancy Age: BMR declines with age

Estimating Energy Requirements Physical activity

Estimating Energy Requirements Body composition

Estimating Energy Requirements Body size

Energy Balance Measuring energy balance: BMI Waist to Hip ratio. Body fat percentage

Defining Healthy Body Weight The criterion of health Body mass index (BMI) =weight (kg)/height (m)2

BMI Values Used to Assess Weight

BMI and Mortality

Distribution of Body Weights in U.S. Adults

Defining Healthy Body Weight The criterion of fashion: BMI of Miss America

Age-Adjusted Prevalence of Overweight BMI (25–29 Age-Adjusted Prevalence of Overweight BMI (25–29.9) and Obesity (BMI >30) Percent This slide depicts data from several NHANES surveys using the panel’s definition of overweight as a BMI of 25 to 29.9 kg/m2 and of obesity as a BMI of greater than or equal to 30 kg/m2. From 1960 to 1994, the prevalence of overweight increased slightly from 37.8 to 39.4 percent in men and from 23.6 to 24.7 percent in women. In men and women together, overweight increased from 30.5 to 32.0 percent. During the same time period, however, the prevalence of obesity increased from 10.4 to 19.9 percent in men and from 15.1 to 24.9 percent in women. In men and women together, obesity increased from 12.8 to 22.5 percent. Most of the increase in obesity occurred in the past decade. BMI 25–29.9 BMI >30 CDC/NCHS, United States, 1960-94, ages 20-74 years CORE SET II

NHANES III Prevalence of Hypertension* According to BMI Percent Data from NHANES III show that the prevalence of high blood pressure increases progressively with higher levels of BMI in men and women. The prevalence of high blood pressure in adults with BMI >30 is 41.9 percent for men and 37.8 percent for women, respectively, compared with 14.9 percent for men and 15.2 percent for women with BMI 25. Other studies, such as the large international Intersalt study, carried out in more than 10,000 men and women, also reported a 10 kg (22 lb) higher body weight to be associated with a 3 mm Hg systolic and 2.3 mm Hg diastolic change in blood pressure. These differences in blood pressure, as shown in the Intersalt study, translate into a 12 percent increased risk for CHD and 24 percent increased risk for stroke. *Defined as mean systolic blood pressure 140 mm Hg, mean diastolic 90 mm Hg, or currently taking antihypertensive medication. Brown C et al. Body Mass Index and the Prevalence of Hypertension and Dyslipidemia. Obes Res. 2000; 8:605-619. CORE SET II

NHANES III Prevalence of High Blood Cholesterol* According to BMI Percent The NHANES III data on high blood cholesterol also show that the prevalence of high blood cholesterol increases at higher BMI levels. High blood cholesterol is defined as a cholesterol level of  240 mg/dL. Among men, the prevalence of high blood cholesterol ranged from 13% at the lowest BMI level to 22% at the highest BMI level. At each BMI level, the prevalence of high blood cholesterol is greater in women than in men. In women, there is a significant increase in the prevalence of high blood cholesterol from BMI level <25 to BMI level 25–26. *Defined as >240 mg/dL. Brown C et al. Body Mass Index and the Prevalence of Hypertension and Dyslipidemia. Obes Res. 2000; 8:605-619. CORE SET II

NHANES III Prevalence of Low HDL-Cholesterol* According to BMI Percent This slide shows that with increasing BMI levels, the prevalence of low HDL increases in both men and women. Low HDL was defined here as <35 mg/dL in men and <45 mg/dL in women. The prevalence of low HDL is more prevalent in women than in men at each level of BMI. Although low HDL-cholesterol in this study was defined as <35 mg/dL in men and <45 mg/dL in women, the Third Report of the National Cholesterol Education Program’s Expert Panel on the Detection, Evaluation, and Treatment of High Blood Cholesterol in Adults defines low HDL-cholesterol as <40 mg/dL for men and women. *Defined as <35 mg/dL in men and <45 mg/dL in women. Brown C et al. Body Mass Index and the Prevalence of Hypertension and Dyslipidemia. Obes Res. 2000;8:605-619. CORE SET II

Hypertension Percentage 60 50 40 Percentage 30 20 Data in the next 8 slides show results of a population-based longitudinal study by Brown and colleagues. The Australian Longitudinal Study on Women’s Health enrolled 13,431 women who participated in a baseline survey of selected indicators of health and well-being for middle-aged women, age 45-49. The study explored the associations between body mass index and selected indicators of health and well-being; surgical procedures(cholescystectomy, hysterectomy), symptoms like back pain, and number of visits to general practitioners or specialists. BMI was calculated using self-reported height and weight, corrected following the method of Waters. Hypertension shows a strong monotonic relationship with BMI. Trend curve estimates the relationship between BMI and hypertension. The percentage of reported hypertension increases with increasing body mass index. The prevalence of hypertension at different levels of BMI were 10.6%(BMI <20), 13.3% (BMI>20<25), 22.8%(BMI>30<40), and 61.3%(BMI>40). There was a 6-fold increase in the odds ratio of hypertension between women with BMI<20 and women with BMI >40. 10 20 25 30 35 40 BMI Relationship between BMI and crude percentage of women reporting medical problems, surgical procedures, symptoms, and health care utilization. Brown WJ et al. Int J Obes 1998;22:520-528. BACKGROUND V

Diabetes Percentage BMI 15 10 Percentage 5 Diabetes, as described in the study by Brown and colleagues of Australian women , shows a monotonic relationship with BMI. The prevalence of diabetes increases 6-fold between women with a BMI < 20 and women with a BMI > 40. Most of the increase in diabetes prevalence occurs in women with BMI >30. Prevalence is 1.6% at BMI < 20, 1.4% at BMI > 20-< 25, 3.2% at BMI > 25-< 30, 5.9% at BMI > 30-< 40, and 19.3% at BMI > 40. There is a 16-fold increase in the odds ratio for diabetes between women with BMI < 20 and women with BMI > 40. 20 25 30 35 40 BMI Relationship between BMI and crude percentage of women reporting medical problems, surgical procedures, symptoms, and health care utilization. Brown WJ et al. Int J Obes 1998;22:520-528. BACKGROUND V

Cholescystectomy Percentage BMI 25 20 Percentage 15 10 In the study by Brown and colleagues, the relationship between BMI and cholescystectomy also shows an upward trend with increasing BMI. A linear increase of increasing surgical procedures is seen for cholescystectomy as BMI increases. There is a 7-fold increase in the odds ratio of cholescystectomy in women with a BMI of < 20 compared to women with a BMI of > 40. 5 20 25 30 35 40 BMI Relationship between BMI and crude percentage of women reporting medical problems, surgical procedures, symptoms, and health care utilization. Brown WJ et al. Int J Obes 1998;22:520-528. BACKGROUND V

Hysterectomy Percentage BMI 40 35 30 Percentage 25 20 This trend curve shows the relationship between BMI and hysterectomy in Australian women in the study by Brown and colleagues. However, the greatest prevalence of hysterectomy occurs in women with BMI > 30 and < 40. The general trend continues to show women with the lowest BMI having this surgical procedure less often than those with a higher BMI. There is a higher risk of surgical procedures in obese women, which may account for the lower prevalence in women with BMI > 40. 15 20 25 30 35 40 BMI Relationship between BMI and crude percentage of women reporting medical problems, surgical procedures, symptoms, and health care utilization. Brown WJ et al. Int J Obes 1998;22:520-528. BACKGROUND V

Back Pain 35 30 Percentage 25 20 Back pain is described in the study by Brown and colleagues as increasing with higher BMI. This trend curve shows the relationship between BMI and back pain. There is a 40% increase in the odds ratio of back pain between women with BMI < 20 and women with BMI > 40. Back pain is one of the most common symptoms reported by women in studies of health concerns. 15 20 25 30 35 40 BMI Relationship between BMI and crude percentage of women reporting medical problems, surgical procedures, symptoms, and health care utilization. Brown WJ et al. Int J Obes 1998;22:520-528. BACKGROUND V

Constant Tiredness Percentage BMI 35 30 Percentage 25 20 The percentage of women reporting constant tiredness in the study by Brown and colleagues increases with increasing body mass index. This graph shows the trend curve estimated to show the relationship between BMI and constant tiredness. There is a J-curve associated with tiredness. Women with BMI < 20 report higher feelings of tiredness than those with BMI between 20 and 30, and are almost equivalent to those with BMI between 30 and 40. There is a 70% increase in odds ratio between women with BMI < 20 and those with BMI > 40. 15 20 25 30 35 40 BMI Relationship between BMI and crude percentage of women reporting medical problems, surgical procedures, symptoms, and health care utilization. Brown WJ et al. Int J Obes 1998;22:520-528. BACKGROUND V

More Than Three Specialist Consultations 10 8 Percentage 6 4 Brown and colleagues found that consultations with general practitioners and visits to specialists increased with increasing BMI among women. The next two slides show this relationship. Among women there is a trend curve estimated to show the relationship between BMI and specialist consultations. The percentage of reported specialist consultations showed a J-curve relationship with BMI. The lowest utilization of specialists occurred with a BMI of 24 to 25. 2 20 25 30 35 40 BMI Relationship between BMI and crude percentage of women reporting medical problems, surgical procedures, symptoms, and health care utilization. Brown WJ et al. Int J Obes 1998;22:520-528. BACKGROUND V

More Than Five GP Consultations 30 25 Percentage 20 15 Brown and colleagues reviewed utilization of general practitioners by women and found a J-curve trend with increasing BMI. Low BMI was associated with fewer physical health problems than mid-level or higher BMI. Indicators of health care use showed a J-shaped relationship with BMI for general practitioners. Prevalence of medical problems (for example, hypertension and diabetes), surgical procedures (cholescystectomy, hysterectomy) and symptoms (for example, back pain) increased monotonically with BMI. This study provides strong support for the recommended BMI range of 20-25 was an appropriate target for the promotion of healthy weight in middle-aged Australian women. 10 20 25 30 35 40 BMI Relationship between BMI and crude percentage of women reporting medical problems, surgical procedures, symptoms, and health care utilization. Brown WJ et al. Int J Obes 1998;22:520-528. BACKGROUND V

Relationship of BMI to Excess Mortality 300 Age at Issue 20-29 250 30-39 200 Mortality Ratio 150 100 Low Moderate High A paper by George Bray examined the relationship of BMI to excess mortality. Data was pooled from 5 prospective studies (3 industrial and 2 community) and included a total sample of 8,422 white males with a mean length of followup of 8.6 years. This slide points out the relationship of BMI to excess mortality. There is a curvilinear increase in excess mortality with rising BMI. The risk is low with a BMI of 25 to30 and increases as BMI increases. The greatest risk is seen with BMIs above 40. 50 Risk Risk Risk 15 20 25 30 35 40 Body Mass Index (kg/[m2]) Bray GA. Overweight is risking fate. Definition, classification, prevalence and risks. Ann NY Acad Sci 1987;499:14-28. BACKGROUND IV

Background Approximately 108 million American adults are overweight or obese. Increased risk of: Hypertension Type 2 diabetes Coronary heart disease Gallbladder disease Certain cancers Dyslipidemia Stroke Osteoarthritis Sleep apnea Based on the 1999 NHANES data, about 61 percent of adults, or an estimated 108 million adults, in the United States are overweight or obese, a condition that substantially increases their risk for hypertension, dyslipidemia, type 2 diabetes, stroke, coronary heart disease, osteoarthritis, gallbladder disease, sleep apnea and respiratory problems, and endometrial, breast, prostate, and colon cancers. Higher body weight is also associated with increases in all-cause mortality. Obese individuals may also suffer from social stigmatization and discrimination. CDC/NCHS NHANES 1999 CORE SET I

Body Fat and Its Distribution Fat distribution Intra-abdominal fat Central obesity

Body Fat and Its Distribution Fat distribution is determined by waist to hip ratio Intra-abdominal fat Waist:Ratio < .8 ♀ or .95 ♂ Central obesity Waist:Ratio > .8 ♀ or .95 ♂

Body Fat and Its Distribution For both men and women, a waist-to-hip ratio of 1.0 or higher is considered "at risk" or in the danger zone for undesirable health consequences, such as heart disease and other ailments connected with being overweight. A ratio of .90 or less is considered safe. This means that your waist is 90% of your hips...so you can do your belt up tighter around your waist than your hips.

Body Fat and Its Distribution

Body Fat and Its Distribution Fatfold measure

Body Fat and Its Distribution Hydrodensitometry

Body Fat and Its Distribution Bioelectrical impedance

Body Fat and Its Distribution Air displacement plethysmography

Body Fat and Its Distribution Dual energy X-ray absorptiometry (DEXA)

Methods Used to Assess Body Fat

Health Risks Associated With Body Weight and Body Fat Health risks of underweight Health risks of overweight

Health Risks Associated With Body Weight and Body Fat Health risks of underweight May be associated with poor nutrition (smoking, substance abuse, illness) Wasting diseases or medical stress Infertility

Health Risks Associated With Body Weight and Body Fat Health risks of overweight Diabetes Hypertension Cardiovascular disease Sleep apnea Cancer Gall bladder disease Respiratory ptoblems

BMI and Mortality

It’s The Calories Stupid Your body can convert all macronutrients to fat. 3000 calories equals a pound, no matter how the macronutrient is consumed.