11/17/2009. HPER 3970 Dr. Ayers (courtesy of Dr. Cheatham)

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1 Weight Management Chapter 11 HPER 3970 Dr. Ayers (courtesy of Dr. Cheatham) Weight Loss Introduction Many athletes, although not overweight, seek to lose body weight (especially body fat) Increase Power to Weight ratio Reduce energy expenditure Example: While running Appearance, stereotypes Can be disadvantages to weight loss Reduction in muscle mass Reduced muscle glycogen stores Chronic fatigue, increased injuries Eating disorders 1

2 General Principles of Weight Management Caloric/Energy Balance = caloric intake caloric expenditure Positive Caloric/Energy Balance Caloric Intake > Caloric Expenditure (Weight Gain) Negative Caloric/Energy Balance Caloric Intake < Caloric Expenditure (Weight Loss) To shift the energy balance equation to result in weight loss: 1. Reducecaloric caloric intake below daily energy requirements 2. Maintain caloric intake and increase energy expenditure through additional activity above daily energy requirements 3. Decrease daily caloric intake and increase daily energy expenditure General Principles of Weight Management 2

3 General Guidelines for Weight Management Target a long term reduction in body weight of at least 5% to 10% Include appropriate exercise recommendations Reduce dietary fat intake to < 30% of total energy intake Emphasize fruits, vegetables, whole grains, and lean sources of protein Caloric intake should not be less than 1200 kcal/day for females or 1800 kcal/day for males Provide a negative energy balance of 500 to 1000 kcal/day Translates to approximately 0.5 to 1 kg (1 to 2 lbs) per week Include behavior modification Weight Loss Defining Goals Often times based on % BF Men should not be less than 5% Women should not be less than 12% These are very low body fat percentages Ideal Body Weight IBW = FFW / (1 Desired %BF) %BF expressed as a decimal (i.e. 15% = 0.15) Realistic Goals: 1 lbs per week Reduction of energy intake no more than kcal/day 3

4 Weight Loss Energy and Substrate Balances Negative energy balanced required to lose weight Reduce energy intake Increase energy expenditure Substrate Balance Excess CHO and PRO can be converted and stored as fat Energy required required process that does not occur easily Fat is rarely converted to CHO and PRO Doesn t increase metabolic rate like CHO and PRO does So, more likely to be stored Weight Loss Energy and Substrate Balances Therefore, reducing dietary fat intake can be an effective strategy for weight loss: Energy dense Taste good: more likely to eat more Efficiently stored with minimal energy for digestion Fat intake does not immediately increase fat oxidation 4

5 Weight Loss Common Mistakes Too rapid loss of weight Usually fluid (dehydration) During on season Skipping meals (breakfast, lunch) May effect training Usually compensated for by large meal Too little CHO intake CHO has a protein sparing effect Weight Loss Decreased Resting Energy Expenditure Over time, losing body weight becomes more difficult due to increased efficiency of the body Decreased RMR Body s preservation of energy Concept of Set Point Typically, bodyweight varies only by about 0.5% over periods of 6 10 weeks. 5

6 Weight Loss Decreased Resting Energy Expenditure Weight Loss Weight Cycling: The Yo Yo Effect Some research has shown that weight cycling is associated with increased mortality However, when taking into account pre existing disease, probably not much association Risks from obesity far outweigh any potential risks associated with weight cycling 6

7 Weight Loss Gender Differences Weight loss greater in males compared to females after aerobic type exercise programs Most likely due to differences in fat distribution abdominal fat is more metabolically active & has higher rates of lipolysis in response to adrenergic stimulation Weight Loss Methods 7

8 Weight Loss Methods Energy Restriction and Reduced Fat Intake Debate over whether or not weight loss can be achieved by reducing energy intake or by reducing fat intake only Some evidence that reducing the % of fat in the diet is more effective than reducing the absolute amount of fat Regardless, energy intake is the most important factor. Energyrestriction restriction is more successful than ad libitum low fat eating Advantages of reduced fat intake Maintenance of CHO and thus glycogen So for athletes, ideal strategy may be minor reduction in caloric intake while eating a relatively low fat diet Weight Loss Methods Very Low Energy Diets Usually used for obese individuals Typically liquid meals that provide about kcal/day High in PRO & low in CHO Weight loss timeframe: Initially very high: glycogen and water Then, most weight loss comes from fat oxidation with some losses of body proteins Increased fat oxidation leads to ketosis Ketosis is process by which the liver converts fat and fatty acids into ketone bodies which can be utilized for energy by many of the cells of the body Exercise capacity decreased 8

9 Weight Loss Methods Food Combination Diets Based on philosophy that certain foods should not be combined Most often these diets suggest avoidance of the combination of PRO and CHO foods These diets aremost likely effective due to decreased energy intake and fat intake, not the avoidance of certain food combinations Weight Loss Methods High Protein Diets Based on suggestions that: PRO decreases appetite Larger thermic effect, low digestibility coefficient Long term health affects are questionable: PRO intake 2 3x greater than recommended: Urinary calcium loss Bone mineral loss Kidney disease (especially in diabetics) 9

10 Weight Loss Methods The Zone Diet 40% CHO, 30% FAT, 30% PRO 3 meals and 2 snacks per day Theory: Increased lipolysis Reduction of insulin Increase in good eicosanoids Hormone like derivatives of fatty acids that act as cell cell signaling molecules Improve blood flow, oxygen transport Reality: Diet can be effective due to the fact that it is essentially low in caloric intake Also, the role of good eicosanoids in blood flow and oxygen transport is questionable TAKE HOME: Zone is more ergolytic than ergogenic to performance Weight Loss Methods Low CHO Diets Atkins, Sugar Busters Theory: Reduced CHO intake leads to increased fat oxidation Reality: Increase in ketone bodies which may suppress appetite Probably work due to the low caloric intake associated with these diets Vitamin and mineral intake is of concern Long term health effects?? Not good for athletes 10

11 Weight Loss Exercise to Lose Weight Combination of diet and exercise the most effective weight loss strategy Maximal rates of fat oxidation are associated with exercise between 55 65% VO Endurance type exercise Role of Resistance Training: Preserving fat free free mass VO 2max Increases metabolically active tissue Helps counteract reductions in RMR associated with decreased caloric intake Determination of Proper Caloric Intake To determine proper caloric intake, we have to approximate an individual s total daily energy expenditure. This will give us a starting point to determine how many calories are necessary to be in energy balance 11

12 Determination of Proper Caloric Intake 1) Using Harris Benedict Equation (BMR): For Males: BMR (kcal/day) = (13.75 x body weight; kg) + (5.0 x height; cm) (6.76 x age; yr) For Females: BMR (kcal/day) = (9.56 x body weight; kg) + (1.85 x height; cm) (4.68 x age; yr) Then, to estimate Total Daily Energy Expenditure: For a person confined to bed rest: Daily EE (kcal/day) = BMR x 1.2 Sedentary both in work and leisure: Daily EE (kcal/day) = BMR x 1.3 Somewhat active life: Daily EE (kcal/day) = BMR x 1.4 Very active life: Daily EE (kcal/day) = BMR x 1.5 Determination of Proper Caloric Intake 2) Using Standard BMR and Body Surface Area: Resting Daily EnergyExpenditure Expenditure (kcal/day) = Standard Value x BSA x 24 Use nomogram on next slide to estimate BSA 34.9 x 1.7 x 24 For Total DEE, you can use same factors as Harris Benedict Equation 12

13 Determination of Proper Caloric Intake Determination of Proper Caloric Intake 3) Using Fat Free Free Mass: RDEE (kcal/day) = (21.6 x FFM; kg) For Total DEE, use same factors as Harris Benedict Equation 13

14 Case Study Example: Ralph (45 year old male) Bodyweight = 210 lbs (95.5 kg) Height = 5 10 (177.8 cm) % Body Fat = 22% Goal % Body Fat = 15% Ideal Body Weight = 193 lbs Overall Weight Loss Goal = 17 lbs (~ 8% weight loss) Exercise: 300 kcal/day of exercise, 5 days of exercise per week Case Study Resting Metabolic Rate Harris Benedict Equation BMR (kcal/day) = (13.75 x body weight; kg) + (5.0 x height; cm) (6.76 x age; yr) BMR = 1964 kcal/day TDEE = 1964 x 1.3 = 2553 kcal/day BSA Equation RDEE = 36.2 x 213x = 1851 kcal/day TDEE = 1851 x 1.3 = 2406 kcal/day FFM Equation RDEE = (21.6 x 74.5) = 1979 kcal/day TDEE = 1979 x 1.3 = 2573 kcal/day 14

15 Case Study Caloric Intake Caloric Expenditure Component kcal/day kcal/week Component kcal/day kcal/week Diet 2,017 14,121 TDEE (w/o ,871 added exercise) Added Exercise 300 kcal/session 1,500 Total 2,017 14,121 Total 2,767 19,371 Goal weight loss = 1.5 lbs/week = 3500 kcal x 1.5 = 5250 kcal negative balance per week. If caloric expenditure per week is 19,371 kcal, then caloric intake for the week needs to be 14,121 (~750/day deficit) General Guidelines for Athletes Determine a realistic body weight goal Do not try to lose more than 1 lb/week Do not restrict caloric intake by more than kcal/day Eat more fruits and vegetables Choose low fat snacks Avoid large meals and instead eat 5 6 smaller meals Keep CHO intake high (especially post training) training) A multi vitamin may be helpful Measure body weight daily and get %BF assessed every 2 months 15