Exer Nutr c11-weight 1 Energy balance. Exer Nutr c11-weight 2 Body composition measurement Gold standard: hydrostatic (underwater) Skinfolds: accurate

Exer Nutr c11-weight 1

Energy balance


Body composition measurement Gold standard: hydrostatic (underwater) Skinfolds: accurate when taken properly

Several sites, converted to %fat by equations Bioelectrical impedance analysis

Based on resistance to electrical current Affected by alcohol, exercise, meal/water

Dual energy X-ray absorptiometry (DEXA) Clinical standard for measuring bone density 2 different intensities, can distinguish soft tissues, bones,

muscles, fat Affected by hydration status













Body composition measurement Computed tomography (CT)

Qualitative and quantitative info about total area of tissue, thickness and volume of tissues within organ

Fat surrounding tissue, fat within tissue Magnetic resonance imaging (MRI)

Similar to results of CT, but use elctromagnetic radiation rather than ionizing radiation

Air displacement plethysmography Same principle as hydrostatic, but use air rather

than water





Normal range of body weight and fat

Essential body fat ~3% BW for men, ~12% for women

General body fat 12-15% for young men, 25-28% for young

women NO body fat standard for athletes

Ideal body composition highly dependent on particular sport


Genetics on body weight

Estimated 25-40% adiposity result of genes >250 genes potential to influence body fatness

Identical twins: variation within pairs << variations between pairs Under energy surplus or deficiency



Weight loss NO lower than essential fat Realistic weight loss ~1 kg every 2 weeks

Reduce 500 kcal/day Energy and substrate balance

↑oxidation rate of CHO and protein immediately when excess amounts ingested, not fat

Excess fat consumption: no increase in oxidation rate, no conversion to CHO or protein, storage

Fat: energy dense, usually taste good Fat efficiently stored, require very little energy for

digestion ↓dietary fat effective for weight loss


Common mistakes for weight loss

Trying to lose weight too rapidly Mostly dehydration Weight loss without performance loss has to occur

slowly Trying to lose weight during on-season

Underperformance: hard training is difficult when energy intake reduced

Weight loss best accomplished during off-season Not eating breakfast or lunch

Increase hunger feelings, may eat more Too little CHO intake

Provide energy for training, protein-sparing


‘Set point’ theory

Body has a weight ‘set point’ Maintenance of reduced or elevated body weight

associated with compensatory changes in energy expenditure (BMR)

Weight cycling: yo-yo effect After weight loss, it is regained in relatively

short time





Gender difference

Weight loss after aerobic exercise training: greater effect for males

Women store more fat in gluteal-femoral region, men in visceral (abdominal) region Fat in upper body and abdominal region more

metabolically active, higher rate of lipolysis in response to adrenergic stimulation

During exercise, FA preferentially mobilized from upper body and abdominal region

Women greater resistance to weight loss


Weight-loss methods Energy and fat restriction

Maintain reasonable glycogen stores Very-low-energy diets

400-800 kcal/d, usually liquid meals ↑fat oxidation ketosis protein loss for gluconeogenesis

High-protein diets ↑sensation of satiety, ↑thermic effect of feeding

Zone diets: 40en% CHO, 30% fat, 30% protein 1000-2000 kcal/d, low energy Claimed to ↓insulin, ↑lipolysis, ↑favorable eicosanoids little

scientific evidence Low-CHO diet: ketogenic, Atkins diet

↑ Ketone bodies ↓appetite, loss of energy in urine (100-150 kcal/d)

Relatively high fat, ↓glycogen


Exercise to lose weight Combine exercise and diet: most effective way to

maintain lower body weight after weight reduction Exercise intensity?

Fat oxidation inhibited > 75% VO2max, but higher energy expenditure

Max rate of fat oxidation 55-65% VO2max Resistance training help to prevent reduction in

BMR Resistance training at least as effective as aerobic

exercise in reducing body fat


Caloric reduction + walking / jogging,

Obese female




Weight cycling in athletes Repeated cycles of weight loss and weight

gain basal metabolic rate, more difficult to lose

weight Plasma concentrations: albumin, prealbumin,

retinal binding protein body protein status

Reduce the numbers of making weight Select the appropriate weight class Maintain appropriate body weight Compete in higher class in less important games


Guidelines for weight loss Determine realistic body-weight goal Lose no more than 0.5 kg/week Eat more fruits, vegetables Low-fat snacks Study food labels, avoid high-fat food Limit fat add-ons 5-6 smaller meals Avoid eating very large meals High CHO intake, consume CHO immediately after

training Miltivitamin and mineral supplements helpful


Making weight

Dehydration: detrimental to performance and dangerous ↓plasma volume, hyperthermia

Gaining weight: energy intake > expenditure ↑CHO intake, not fat intake Realistic 0.2-1 kg/week Protein synthesis is slow process


Study results - 1 角力選手，分別使用高醣 (70% 熱量來自醣類 ) 或低醣 (55%) 的低熱量飲食 21.9 kcal/kg 無脂肌質 /day , 7 天後低醣組在 Wingate test 的總功輸出較節食前顯著降低 (-7%)

高醣組則在節食前後無顯著差異在經過 4 天的節食而減少約 6% 的體重後，使用高醣飲食 (65.9%) 的受測者在 6 分鐘間歇性高強度的手部腳踏車測試所做的總功與節食前無顯著差異使用低醣飲食 (41.9%) 者則較節食前顯著降低


Study results - 2 角力選手 : 低熱量配方飲食 72 小時後

(18 kcal/kg 體重， 60% 熱量來自醣類， 20% 蛋白質，20% 脂肪 ), 流失 3.3% 原體重

接下來的 150 分鐘，給予 21 kcal/kg 體重的營養補充分為高醣 (75% 醣類， 10% 蛋白質， 15% 脂肪 ) 與低醣 (47% 醣類， 16% 蛋白質， 37% 脂肪 ) 兩組

在節食前 (test 1) 、節食後 (test 2) 、和開始補充5 小時後 (test 3) ，以固定式手部腳踏車進行 4.5分鐘的間歇最高強度測試兩組 test 2 的總功 (total work) < test 1 高醣組在 test 3 總功已恢復到 test 1 的 99.1% 低醣組在 test 3 總功為 test 1 的 91.5% ，且與 test 2相似


Study results - 3 Case study of an elite male wrestler 1. making weight to 52 kg

熱量攝取從平均每天約 2070 kcal 減少至 1900 kcal 62% 醣類， 20% 蛋白質， 18% 脂肪 54.88 公斤 ( 體脂肪 4.8%) 53.25 公斤 ( 體脂肪 3.8

%) 在比賽前再脫水 1.4 公斤而達到 52 公斤

2. 17 天內降至 50.59 公斤 ( 體脂肪 1.1%) Energy intake 自 1831 kcal/d 降至比賽前三天的 1153

kcal/d 醣類 62-65% ，蛋白質 23-26% ，脂肪 11% 比賽前再脫水 2.73 公斤而達到 48 公斤的參賽標準

肌力與有氧能力仍維保持與降體重前相當


降體重期間的營養 High protein, high CHO, very low fat

~ 2 g protein/kg 飯麵或麵包一定要吃 : 提供足夠醣類減少脂肪攝取

去皮去油不喝湯不吃炸煎的食物過水脫脂奶或優酪乳

每天吃一顆綜合維他命過磅前約一星期減少鹽份攝取避免水份堆積

儘量少吃各種調味料醬油醬汁可加少許胡椒或醋儘量少吃醃製的食品和零食停止使用肌酸

過磅前 1-2 天少吃高纖維的食物避免殘留腸道中避免早餐營養穀片全麥麵包豆類花椰菜芹菜蘆筍


可使用的營養補充品 BCAA, beta-hydroxy-beta-methylbutyrate

(HMB), may helpful 飯 + 水果 +( 脫脂牛奶 )+ 健怡美而力

+HMB 善存 1-2 顆 75% CHO, 2-3 g protein /kg BW 120 g protein = 480 kcal 2500 –480 = 2000 kcal = 500 g CHO , ~8 g/kg 720/1200 = 60% CHO


過磅後的營養補充若過磅後 1-2 小時即要比賽

過磅後迅速補充碳水化合物包括香蕉麵包約 20-30分鐘一次（先試驗避免腸胃不適）

其他水果果汁含果糖可能引起腸胃不適注意水份的攝取至少需補充至過磅前體重 ( 或適量）比賽前 10-15 分鐘喝 200-300 ml 運動飲料（先試驗避免低血糖）

若過磅後隔天才比賽過磅後迅速補充碳水化合物包括香蕉蘋果果汁麵包運動飲料

避免大吃大喝應該分散成數餐或每隔 2-3 小時吃一次，但每次份量不要太多

少吃油脂和肉類以飯麵包水果為主

New drugs for weight reduction

liraglutide, a glucagon-like peptide-1 (GLP-1) receptor agonist, approved by FDA in December, 2014 Via injection Previously approved for treatment of type 2

diabetes GLP1R is known to be expressed in pancreatic

beta cells. Activated GLP1R stimulates the adenylyl cyclase pathway which results in increased insulin synthesis and release of insulin


Documents

Exer Nutr c11-weight 1 Energy balance. Exer Nutr c11-weight 2 Body composition measurement Gold standard: hydrostatic (underwater) Skinfolds: accurate