Energy Balance

Daily energy expenditure consists of three components: basal metabolic rate (BMR), diet-induced thermogenesis (DIT) and energy cost of physical activity.   10% Thermic effect of food   20-30% Activity   60-70% Resting metabolic rate Thermic Effect of Food Energy required to digest, absorb, transport, and store food. Diet induced thermogenesis (DIT) is different for each nutrient based on the amount of ATP required for the initial steps of metabolism and storage. Nutrient Fat Carbohydrate Protein Alcohol DIT (% Energy) 0-3% 5-10% 20-30% 10-30% Reference Acheson KJ, 1983 Westerterp KR, 1999 In healthy subjects with a mixed diet, where intake equals expenditure, DIT represents about 10% of the total amount of energy ingested over 24 hours. Westerterp, KR (2004) Diet induced thermogenesis, Nutrition & Metabolism 2004, 1:5 Also see Exchange List Calculator. Activity Daily Activity Exercise Aerobic exercise Expends calories during exercise Anaerobic exercise can increase metabolism for hours after exercise is finished 3-14 hours: dependent upon intensity HIIT study: for every calorie expended during anaerobics, 9 times as much fat (per calorie expended) was metabolized as compared to aerobic activity. Online calculators Calorie Requirement Calculator Metabolic Calculators: Walk / Run | Cycling | Stepping Resting Metabolic Rate Energy expended to maintain the body during resting conditions. Proportional to muscle mass Muscle is more metabolically active than fat May account a smaller proportion of the daily caloric needs for those who have regular vigorous exercise. Also see Calorie Requirement Calculator. Energy Balance Neutral energy balance is when the calories you take in is equal to the calories expended. Weight is maintained. Positive energy balance is when the calories you take in is greater than the calories expended. Weight is gained and fat stores are increased. One pound of fat contains approximately 3500 Calories. Negative energy balance: calories you take in is less than the calories expended. Adipose, glycogen, and muscle can be used for energy to make up the caloric deficiency. Ideally weight is lost and fat stores are reduced. Appetite Appetite is increased in proportion to energy expenditure over a broad range of exercise intensities and durations to maintain body weight. However, formerly sedentary individuals show a net loss of appetite when exercise is introduced. Titchenal, CA. 1988. Exercise and food intake: What is the relationship? Sports Medicine 6:135-45. The metabolism adjusts to changes in diet If calories are increased Thermo-genesis Body heat is produced Metabolism increases Muscle mass may increase If calories are restricted Metabolism decreases Muscle mass may decrease A cascade of metabolic / hormonal changes allow the body to adapt