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 is measured in calories Energy Balance and Healthy Body Weight

3. 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

4. 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

5. Energy Expenditure • A- components: 3 forms of energy • Resting energy expenditure: used by the body at rest, awake and for all vital functions • Energy expenditure during physical activity • Thermic effect of food: energy used for digestion • The sum of all three = Total Energy Expenditure (TEE) Energy Balance and Healthy Body Weight

6. Resting Energy Expenditure (BMR) • 60-70 % of TEE • Energy spent by the body for various physiological and biological activities • REE is expressed in Kcal/hr • Energy expenditure of different organs is different Energy Balance and Healthy Body Weight

7. Resting Energy Expenditure (BMR) • Factors affecting REE/BMR: • Body weight, in particular, lean body mass (Boy mass – fat mass). As lean mass increases, REE increases • Body surface, as that increases, BMR increases • Sex: RMR 5-10 % lower in women • Highest during rapid growth phases (infancy) • Decrease with aging Energy Balance and Healthy Body Weight

8. Resting Energy Expenditure (BMR) • Hormones: growth hormones, thyroxine and adrenaline • Fever: RMR increases • Sleep: RMR decreases • Environmental Temp: RMR increases in cold and hot temperatures • Pregnancy: RMR increases • Nutritional state: Eating less calories decreases RMR • Caffeine and nicotine increase RMR Energy Balance and Healthy Body Weight

9. Physical Activity (PA) • Expenditure varies greatly among people, according to their level of activity • Sedentary activity: 20-40 % as big as BM • Light activity: 55-65 % as big as BM • Moderate activity: 70-75 % • Heavy activity: 80-100 % • Mental activity does not significantly increase BMR Energy Balance and Healthy Body Weight

10. Thermic Effects of Food • Also known as “Diet-induced Thermogenesis” • Energy spent to digest and absorb nutrients • Depends on the nature of consumed foods (highest for proteins>CHO>fat Energy Balance and Healthy Body Weight

11. Measurement and Estimation • Direct Calorimetry: • By measuring heat production by body • Individual inside an insulated chamber with water pipes measuring the rise of water temperature in degrees Celsius • Provides no information on the kind of fuel being catabolized Energy Balance and Healthy Body Weight

12. Measurement and Estimation • Indirect Calorimetry • By measuring oxygen consumption and carbon dioxide production • Provides 2 kinds of information: • Amount of expended energy: 1 liter of oxygen consumed = 5 Cal expended • Fuel being catabolized through the respiratory Quotient (RQ) : CO2 expired/O2 consumed Energy Balance and Healthy Body Weight

13. Estimations • Standard tables and equations that consider sex, height, weight, age and level of activity • REE: simple formula for women: Body wt. (kg) * 0.9 * 24 • Men: Kg *1*24 • PA: Sedentary: 20-40 % … • TEF: 10 % (REE + PA) • TEE: REE + PA + TEF Energy Balance and Healthy Body Weight

14. Energy Balance • Energy intake (food consumption) = Energy expenditure --- stable body weight • Energy intake > expenditure --- increase body wt and vice versa Energy Balance and Healthy Body Weight

15. How Fat is Too Fat? • Obesity is a chronic disease! • 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

16. 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

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

18. 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

19. Estimating Body fatness • Anthropometry: measurements such as fatfold test or waist circumference can be taken • Fatfold test: measurement of the thickness 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 • Conductivity: only lean tissue and water conduct electricity Energy Balance and Healthy Body Weight

20. 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

21. 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

22. Appetite The “go” mechanism that stimulates eating, and the “stop”, which signals the body to stop eating Hunger: physiological need to eat originating in the brain Appetite: the psychological desire to eat Energy Balance and Healthy Body Weight

23. “Stop” Signals: Satiation and Satiety • Satiation: the perception of fullness that builds throughout a meal • Satiety: the perception of fullness that lingers in the hours after a meal and inhibits eating until the next meal time • Leptin is a major source of satiety • Hormone produced by the adipose tissue and directly linked to appetite and body fatness Energy Balance and Healthy Body Weight

24. 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

25. Obesity and Behavior • Fat delivers more than twice the calories of CHO or proteins, is stored avidly, requires the least amount of energy to process with the least amount of diet-induced thermogenesis • Eating behavior occurs in response to yearning, craving, addiction, or compulsion • Arousal feelings are heightened activity of certain brain centers associated with attention, excitement and anxiety– may lead to overeating Energy Balance and Healthy Body Weight

26. Obesity and Behavior • Physical inactivity • Obese people often engage less in physical activity • Best way to fight obesity • Diet therapy • Physical activity • Behavior modification • Sometimes, drugs and surgery are needed (in conjunction with all of the above!) Energy Balance and Healthy Body Weight

27. Physical Activity • Increases energy expenditure • Increases resting BMR (slightly) over a long period of time • Accelerates loss of body fat • Helps regulate appetite • Helps control stress and stress-induced overeating or underrating with subsequent indulgences • Enhances self esteem Energy Balance and Healthy Body Weight

28. Weight Gain and Loss • The difference between energy in and out usually determines the amount of weight gained or lost • If a person exercises appropriately, moderately restricts calories, and consumes a balanced diet that meets proteins and CHO requirements, the body will be forced to use up its stored fat as energy. Gradual weight loss through fat loss and not lean mass will occur Energy Balance and Healthy Body Weight

29. Fasting • In early food deprivation • The nervous system can not use fat as fuel, it needs glucose • Body fat can not be converted to glucose • Body protein can be converted to glucose • Later food deprivation • Protein breaking must halt for life processes to continue • Ketone bodies are produced and feed the nervous system Energy Balance and Healthy Body Weight

30. Fasting • Ketone bodies: acidic compounds derived from fat and certain amino acids. They are normally rare in the body • Ketone bodies usually show up in the blood stream after around ten days of fasting • Ketosis changes the acid-base balance and promotes mineral losses in the urine Energy Balance and Healthy Body Weight

31. Fasting • Food deprivation leads to binge eating and overeating when food is available • This continues even after normal weight is restored • Fasting is not an effective weight loss regimen Energy Balance and Healthy Body Weight

32. Underweight • Causes • Low energy input • Insufficient food intake (unavailability, anorexia) • Poor absorption of consumed food) • High energy output • Excessive physical activity • Hyperthyroidism • Stress (increase adrenalin--- increase RMR) • Two examples are: Anorexia Nervosa and Bulimia Energy Balance and Healthy Body Weight

33. Anorexia Nervosa • A disease state characterized by body image dysmorphia and mood disorder • Patient are TERRIFIED of being overweight, even when they are severely malnourished and underweight • More common in teenage girls • Patients will eat less and less • Anorexia is an attempt to use food to deal with emotional problems Energy Balance and Healthy Body Weight

34. Bulimia • Unlike anorexia, people here do not necessarily starve themselves, exercise or avoid high calorie foods • Characterized by episodes of binge eating and purging (vomiting, laxatives, fasting, medications and diuretics) • Again, related to mood disorders with body dysmorphia • More common in teenage girls Energy Balance and Healthy Body Weight

35. Anorexia Nervosa and Bulimia • Health consequences • Weakness • Sensitivity to cold • Cessation of menstrual periods which leads to osteoporosis, and decrease in testosterone levels in men • Heart irregularities • The two best examples are tow disease states: Anorexia Nervosa and Bulimia Energy Balance and Healthy Body Weight

36. Low CHO Diets • Any diet too low in CHO will produce effects similar to fasting • The diet will decrease appetite and make weight loss quick • Low CHO diets will cause lean tissue and water loss. Patients will rebound as soon as they eat normal again Energy Balance and Healthy Body Weight

37. Weight Gain • Only two kinds of energy stores: Glycogen and fat • Any food can make you fat if you eat enough of it • Fat, as opposed to CHO and protein, from food is especially easy for the body to store as fat tissue • Alcohol both delivers calories and encourages storage of body fat Energy Balance and Healthy Body Weight

38. Weight Gain • Protein is not stored in the body except in response to exercise; it is present only as working tissue • Excess protein is converted to fat and stored as such • Too little physical activity encourages body fat accumulation Energy Balance and Healthy Body Weight

39. Achieving and Maintaining a Healthy Body Weight • The best plans for a healthy body weight: • Keeping records: the best diet is one tailored to your own needs • Setting goals: • Reduce body weight by about 10 % over half a year’s time • Maintain lower body weight over the long term • At a minimum, prevent further weight gain • Set broad goals, and then set small steps to reach them • Weight lost rapidly is gained back rapidly! Energy Balance and Healthy Body Weight

40. Achieving and Maintaining a Healthy Body Weight • Quick fix diets and weight loss gimmicks are ineffective Energy Balance and Healthy Body Weight

41. Diets to Gain Weight • If you are healthy at your weight, stay there • If you are underweight, or as a woman, you have missed at least three menstrual periods, you may be in danger • Healthful weight gain can be done through physical activity. Diet alone will bring on weight gain that is mostly fat • Important to weight gain is the calories to go with the exercise Energy Balance and Healthy Body Weight

42. Diets to Gain Weight • Nutritious calorie dense foods are needed • Some choices to make • Olives instead of pickles, milk shake instead of milk, avocado instead of cucumber … • Expect to feel full, sometimes undesirably so • Eat frequently • Stop smoking Energy Balance and Healthy Body Weight

43. Weight Change Maintenance • The most difficult part of a diet sometimes is to maintain the weight change • A key to weight maintenance is acceptance to the chronic nature of weight management • Acceptance of weight control as a life-long achievement, not a short term goal helps • Usually, behaviors that helped you lose weight are the ones that help you maintain it Energy Balance and Healthy Body Weight

44. Weight Change Maintenance • People who maintain healthy weight also: • Are more physically active than the average person • Monitor fat grams, caloric intake, and body weight • Believe they have the ability to control their weight, an attribute known as self-efficacy, even in the face of previous failures Energy Balance and Healthy Body Weight

45. Weight Change Maintenance • Develop social support systems • Eat controlled portions at planned times, and eat them at a leisurely pace • Eat high-fiber foods, and consume sufficient water each day • Have realistic expectations regarding body size and shape • Weight loss without exercise leads often to weight cycling (yo-yo dieting) Energy Balance and Healthy Body Weight

46. Energy • Can be expressed as • Kilocalories (units of energy based on heat energy; 1 kcal=1 1 Cal=1 Kcal=1000 calorie) • Kilojoules (units of energy based on mechanical energy; 1 Kcal = 4.18 Kj) Energy Balance and Healthy Body Weight

47. Calculating Energy • A 70 kg man is on a 2500 Calorie diet. He exercises moderately. Calculate his BMR and exercise energy levels. • BMR is 70 * 24 = 1680 Cal = 1680 *4.18= 7022.4 Kilojoules • Moderate activity: 70-75 % of 7022.4 Kilojoules= 4915 Kilojoules = 1176 Calories Energy Balance and Healthy Body Weight