Energy Balance and Healthy Body Weight

1. Energy Balance and Healthy Body Weight Zeina Ghossoub, MSc Energy Balance and Healthy Body Weight

2. Energy Balance • Body composition: the proportions of muscle, bone, fat and other tissue that make up a person’s total body weight • Energy balance: energy in and energy out must be balanced, else, excess energy is stored as adipose tissue (body fat) • Change in energy stores = energy in – energy out Energy Balance and Healthy Body Weight

3. Energy In • Measured in calories taken in each day in the form of food and beverages • For each 3500 excess calorie intake, you store 0.5 kg of body fat! • Calories can be obtained by conulting various charts and computer programs Energy Balance and Healthy Body Weight

4. Energy Out • People’s energy needs vary widely • One way of estimating energy needs is to monitor your food intake and body weight over a period of time in which your activities are typical of your life style • If your weight has not changed over a month or two, then your energy budget is balanced Energy Balance and Healthy Body Weight

5. Energy Out • Another method to determine energy needs is based on energy out • Three energy output components, two major and 1 minor (5-10 %) • Minor: Thermic effects of food = speeded-up metabolism in response to having eaten a meal Energy Balance and Healthy Body Weight

6. Energy Out • Two major: • Fuel the basal metabolism • Fuel voluntary activities Energy Balance and Healthy Body Weight

7. Energy Out • The hormone thyroxine directly controls basal metabolism Energy Balance and Healthy Body Weight

8. Energy Out • BMR usually cannot be sped up for losing weight • BMR varies from person to person • Daily activities is the best way we have to lose weight by increasing energy output • With daily increase in physical activity, the BMR will rise • Lean tissue helps increase the BMR Energy Balance and Healthy Body Weight

9. Daily Caloric Needs • Enough to cover your energy needs • Estimation example: Calculate BMR and physical activity expenditure in a 68 kg man • BMR • Multiply weight in kg by the BMR factor (1cal/kg body weight/hour in men and 0.9 in women because of less muscle mass) = 68 *1 = 68 • Multiply the number of hours in a day= 68 * 24 = 1632 calories per day for the BMR Energy Balance and Healthy Body Weight

10. Daily Caloric Needs • Physical activity = BMR energy multiplied by a factor that depends on the amount of activity • Sedentary lifestyle: men= 25-40%, women= 25-35% • Light activity: men=50-70 %, women=40-60 % • Moderate activity: men=65-80 %, women=50-70 % • Heavy activity: men=90-120 %, women=80-100 % • Exceptional activity: men=130-145 %, women=110-130% Energy Balance and Healthy Body Weight

11. Activity Levels Energy Balance and Healthy Body Weight

12. Daily Caloric Needs • Calculate your energy expenditure from activity by using the lower and higher % in the range Energy Balance and Healthy Body Weight

13. Body Fat: Too Little and Too Much • More than 50 % of US citizens are over weight and/or obese • Risks exist for underweight and overweight Energy Balance and Healthy Body Weight

14. What are the Risks of Underweight? • Deficient body fatness threatens survival during a famine or wasting disease (like cancer and HIV) • Wasting is the relentless loss of the body’s tissues that accompanies certain diseases and shortens survival time Energy Balance and Healthy Body Weight

15. How Fat is Too Fat? • Excessive body fat is linked to obesity and overweight, which are linked to • Heart disease • Diabetes • HTN • Cancer • Stroke • Peripheral vascular disease • Kidney failure • Sleep apnea, gallbladder disease and many more Energy Balance and Healthy Body Weight

16. How Fat is Too Fat? • Obesity is a chronic disease! • Central obesity is obesity centered around the abdominal area • Even more than total fatness, fat that accumulates around the central abdomen is an independent risk factor for lipid disorders and heart disease, diabetes, HTN and others • Central obesity adds another factor in disease causation Energy Balance and Healthy Body Weight

17. How Fat is Too Fat? • Central adipose tissue releases fat more readily and easily into the blood stream whereas subcutaneous fat (under the skin) is more sluggish and releases less lipids into the blood • “Apple” profile is fat around the abdomen • “Pear” is around the thighs and hips (typical in reproductive women) Energy Balance and Healthy Body Weight

18. How Fat is Too Fat? • Alcohol is associated with central adiposity • Smoking may keep some people’s weight off, but at a high cost • Heart disease • Cancer • Osteoporosis • Chronic lung disease • Shortened life span • Miscarriage • Sudden infant death syndrome Energy Balance and Healthy Body Weight

19. How Fat is Too Fat? • Social and economic cost of obesity • Careers, emotional and physical sufferings by obese people • They pay for higher insurance premiums, more for clothing • Feel rejected and embarrassed Energy Balance and Healthy Body Weight

20. Body Weight VS. Body Fatness • Body Mass Index (BMI) = weight in kg/square of height in m • For the most part, BMI is a rough estimate of a persons ideal body weight to height ratio • BMI usually correlates with body fatness and degree of disease • In general, the higher the BMI, the more obese the person and the more the diseases Energy Balance and Healthy Body Weight

21. Body Weight VS. Body Fatness Energy Balance and Healthy Body Weight

22. Body Weight VS. Body Fatness Energy Balance and Healthy Body Weight

23. Body Weight VS. Body Fatness • BMI drawbacks • BMI values fail to indicate how much of the weight is fat • Where that fat is located • BMI is not useful with • Athletes • Pregnant and lactating women • Adults over 65 (because BMI data is based on a younger population) Energy Balance and Healthy Body Weight

24. Estimating Body fatness • Without fat and water, a 175 cm, 70 kg man would weigh 15 kg. 15 kg to make up the rest of the body • To lose weight, lose the fat, gain the lean • To gain weight and stay healthy, make sure it is lean tissue that is being gained Energy Balance and Healthy Body Weight

25. Estimating Body fatness • Anthropometry: measurements such as fatfold test or waist circumference can be taken • Fatfold test: measurement of the thckness of a fold of skin on the back of the arm, below the shoulder blade, or in other places • Density: the measurement of body weight compared with volume • Lean tissue is denser than fat, the denser the body, the leaner the tissue Energy Balance and Healthy Body Weight

26. Estimating Body fatness • Density can be determined by underwater weighing • Conductivity: only lean tissue and water conduct electricity • Bioelectrical impedance measures how well a tiny current passes through the body and through special calculations, determines total body fat Energy Balance and Healthy Body Weight

27. Estimating Body fatness Energy Balance and Healthy Body Weight

28. Estimating Body fatness • Inappropriate skin fold measurements may lead to errors in estimation • Skin folds in the belly area predict better the changes in body fat • Waist circumference serves as an indicator of visceral fatness • Correlates independently with disease • Cutoff for men is 102 cm, women is 88 cm Energy Balance and Healthy Body Weight

29. Defining Priorities • For the general public, men should have about 15 % body weight from fat, and women around 20 % • Cutoff points are 22 % for men and 25 % for women • Different standards apply for different people Energy Balance and Healthy Body Weight

30. The Mystery of Obesity • Internal and external factors operate together and in different combinations in different people • Multiple factors are involved Energy Balance and Healthy Body Weight

31. Appetite • The hope is that understanding what drives us to eat will help us in controlling it • Scientists have defined two processes with food intake • The “go” mechanism that stimulates eating, and the “stop”, which signals the body to stop eating Energy Balance and Healthy Body Weight

32. Hunger and Appetite • Hunger: physiological need to eat originating in the brain, in the hypothalamus, delivered via certain neurotransmitters • NYI (neuropeptide Y) simulates appetite, especially appetite for CHO-rich foods • Hunger strikes about 4-6 hours after each meal, when the food has left the stomach and most has been absorbed in the intestine Energy Balance and Healthy Body Weight

33. Hunger and Appetite • Other factors that affect hunger include blood stream products, eating patterns, the size of the prior meal, patterns, mood, the weather, disease states (physical and mental), medications, exercise, sex hormones • Hunger is adaptable to meal sizes Energy Balance and Healthy Body Weight

34. Hunger and Appetite • The feeling of “stomach shrinking” and early satiety occurs with chronic exposure to small meal portions • The stomach has the ability to grow and accommodate larger and larger meals • Restaurant portions are growing and this may contribute to more obesity Energy Balance and Healthy Body Weight

35. Hunger and Appetite • Appetite: the psychological desire to eat: a learned motivation and a positive sensation that accompanies the sight, smell, or thought of appealing foods • Initiates eating and is learned • Appetites and hunger usually go hand in hand, but one can prevail while the other is not present Energy Balance and Healthy Body Weight

36. Hunger and Appetite • Other factors that affect appetites • Learned preferences, aversions, and timings (cravings for favorite foods, fear of new foods, and eating according to the clock) • Environmental conditions • Endorphins (the brain’s pleasure chemicals that enhance the taste of foods) • Inborn appetites Energy Balance and Healthy Body Weight

37. Hunger and Appetite • Social interactions • Some disease states (obesity may be associated with increased taste sensitivity) • Some drugs Energy Balance and Healthy Body Weight

38. “Stop” Signals: Satiation and Satiety • Satiation: the perception of fullness that buolds throughout a meal, eventually reaching the degree of fullness and satisfaction that halts eating • Satiety: the perception of fullness that lingers in the hours after a meal and inhibits eating until the next meal time Energy Balance and Healthy Body Weight

39. “Stop” Signals: Satiation and Satiety Energy Balance and Healthy Body Weight

40. “Stop” Signals: Satiation and Satiety • Leptin is a major source of satiety • Hormone produced by the adipose tissue and directly linked to appetite and body fatness • A lack of satiety between meals may cause hunger and starvation cycles leading to problems with weight • Some foods have more satiety powers than others Energy Balance and Healthy Body Weight

41. “Stop” Signals: Satiation and Satiety Energy Balance and Healthy Body Weight

42. Obesity and Genetics • Obesity and genetics are tightly linked • Children tend to resemble their biological parents • One obese parent raises the risk of obesity to 60 % in a child, two obese parents make it 90 % Energy Balance and Healthy Body Weight

43. Obesity and Genetics Energy Balance and Healthy Body Weight

44. Obesity and Genetics • Leptin is found on the ob gene • Leptin suppresses NYI • Most obese people have already elevated leptin levels in their blood • Very few percentage of obese people fail to produce leptin • There may be a resistance to leptin at its receptor site in thebrain with increasing obesity Energy Balance and Healthy Body Weight

45. Obesity and Genetics • Leptin may decrease central adiposity • May inform the female reproductive system about body fat stores • May stimulate blood vessel growth in the cornea • Act on bone marrow cells to enhance their maturation Energy Balance and Healthy Body Weight

46. Obesity and Genetics • Set-point theory • The theory that the body tends to maintain a certain weight by means of its own internal controls • Biological systems, and not human will, are the ones that usually determine the set-point Energy Balance and Healthy Body Weight

47. Obesity and Genetics • Enzyme theory: strong evidence has linked LPL (lipoprotein lipase), an enzyme, with fat storage • LPL is an enzyme mounted on the surfaces of fat cells that splits TG in the blood into FAcids and glycerol to be absorbed and manipulated in the cell Energy Balance and Healthy Body Weight

48. Obesity and Genetics • LPL concentration increases as cells become enlarged with fat • LPL levels are governed by genes Energy Balance and Healthy Body Weight

49. Obesity and Genetics • Fat cell number theory: the development of fat cells during childhood may play a role • Number of fat cells increases during the growing years and then levels of in adulthood • Cells in adulthood usually only increase in size • More LPL can mean larger sized fat cells reached more easily Energy Balance and Healthy Body Weight

50. Obesity and Genetics • Thermogenesis theory • Genes code for proteins that produce heat • Brown fat is a tissue that specialized in producing heat • The more the brown fat in animals, the leaner the animal • Not much brown fat in adults Energy Balance and Healthy Body Weight