《食品營(yíng)養(yǎng)學(xué)》課件03-營(yíng)養(yǎng)與能量平衡(2)

1、第一節(jié) 能量平衡體內(nèi)能量的收支平衡 食物能量供大于求時(shí)：多余的脂肪進(jìn)入身體脂肪組織中的脂肪細(xì)胞貯存起來(lái)。 攝入能量不足時(shí)：消耗這些脂肪。貯存能量的改變=能量攝入-能量輸出吃得過(guò)多，或吃得過(guò)少時(shí)，身體會(huì)發(fā)生什么變化？改變自身機(jī)體構(gòu)成。當(dāng)進(jìn)食過(guò)多時(shí)當(dāng)進(jìn)食過(guò)少時(shí)（調(diào)用儲(chǔ)備）當(dāng)糖原耗盡，卻未進(jìn)食時(shí)能量的攝入從食物和飲料中攝入的能量是“能量攝入”的唯一來(lái)源。能量的輸出能量消耗構(gòu)成： 基礎(chǔ)代謝 60%65% 人體各種活動(dòng) 25%35% 食物的代謝反應(yīng) 5%10%名稱食物能值尿中損失吸收率（%）生理能值生理系數(shù)kcal/gkJ/gkcal/gkJ/gkcal/gkJ/g蛋白質(zhì)5.6523.61.25 5.2

2、924.0174脂肪9.4539.5959.0389碳水化合物4.117.2984.0174乙醇7.129.7微量1007.1307蛋白質(zhì)在體內(nèi)不能完全被氧化分解，代謝廢物有尿素、尿酸、肌酐等有機(jī)物，隨尿液排出體外，這些物質(zhì)能產(chǎn)生能量5.2kJ/g 。幾種營(yíng)養(yǎng)素的食物能值和生理能值食物能值：是食物徹底燃燒時(shí)所測(cè)定的能值。生理能值：即機(jī)體可利用的能值。能量的攝入中國(guó)食物成分表2010版能量的攝入能量的輸出基礎(chǔ)代謝基礎(chǔ)代謝（basal metabolism）指維持人體基本生命活動(dòng)的能量?；A(chǔ)代謝率（basal metabolic rate， BMR）。它是指單位時(shí)間內(nèi)人體所消耗的基礎(chǔ)代謝能量。BM

3、R的單位：KJ/m2.h、kJ/(kg.h)、MJ/d基本的生命活動(dòng)：體溫，呼吸，血液循環(huán)，腺體分泌，肌肉的一定緊張度等一般來(lái)說(shuō)，成年男子每千克體重每小時(shí)平均耗能1kcal通常，女性的基礎(chǔ)代謝比男性約低5%兒童與青少年基礎(chǔ)代謝比成人高10%-15%因素對(duì)BMR的影響年齡年輕人比中年人高；中年人比老年人高身高個(gè)高的人表面積大，BMR高生長(zhǎng)兒童，孕婦BMR高機(jī)體組成非脂肪組織多，BMR高發(fā)熱發(fā)熱使BMR增高應(yīng)激反應(yīng)應(yīng)激反應(yīng)使BMR增高環(huán)境溫度太高或太低都會(huì)使BMR增高禁食，饑餓降低BMR營(yíng)養(yǎng)不良BMR降低甲狀腺素甲狀腺素是BMR的關(guān)鍵調(diào)控因子，甲狀腺素越多，BMR越高。影響B(tài)MR的因素體力活動(dòng)消耗

4、的熱能在人體總熱能消耗中占主要部分。不同體力活動(dòng)所消耗的熱能不同，除基礎(chǔ)代謝外，勞動(dòng)強(qiáng)度是影響人體熱能消耗最主要的因素。在同樣勞動(dòng)強(qiáng)度下持續(xù)勞動(dòng)時(shí)間和工作熟練成度也有影響。持續(xù)時(shí)越長(zhǎng)，工作越不熟練，能量的消耗越大。 我國(guó)將一般成人體力活動(dòng)分為三級(jí)，即輕體力活動(dòng)、中等體力活動(dòng)和重體力活動(dòng)。能量的輸出體力活動(dòng)對(duì)食物的代謝反應(yīng)（特殊動(dòng)力作用，熱效應(yīng)） 是指人體由于攝食所引起的一種額外熱能損耗。不同營(yíng)養(yǎng)素的熱效應(yīng)各不相同 攝入碳水化合物時(shí)耗熱相當(dāng)于碳水化合物本身產(chǎn)熱的5-6%，脂肪為4-5%，蛋白質(zhì)為30%。 成人攝入一般的混合膳食而增加的耗熱量為600KJ/d左右，相當(dāng)于基礎(chǔ)代謝10%。 食物在消化

5、道進(jìn)行消化、吸收、代謝過(guò)程增加了能量消耗。能量的輸出對(duì)食物的代謝反應(yīng)第二節(jié) 體脂太多或太少帶來(lái)的問(wèn)題體重過(guò)輕的危險(xiǎn)是什么？肥胖帶來(lái)的不便周圍性肥胖中心性肥胖（軀干性肥胖）整體性肥胖評(píng)估身體的發(fā)胖狀況各年齡段成人參考體重評(píng)估身體的發(fā)胖狀況BMI值及患病危險(xiǎn)測(cè)量腰圍用不可拉伸的尺子測(cè)量肚臍部位的腰圍。男子的健康范圍小于102cm；女性則小于88cm。第三節(jié) 肥胖的現(xiàn)狀“Were raising our children the way we raise calves for veal - keep them in boxes, feed them too much, and allow them

6、no exercise.”Rich KillingsworthCenter for Disease Control and PreventionBAGEL 20 Years AgoToday140 calories 3-inch diameter How many calories are in this bagel?140 calories 3-inch diameter Calorie Difference: 210 calories350 calories 6-inch diameterBAGEL 20 Years AgoTodayHow long will you have to ra

7、ke leaves in order to burn the extra 210 calories?* *Based on 130-pound personMaintaining a Healthy Weight is a Balancing ActCalories In = Calories OutIf yourake the leaves for 50 minutes you will burn the extra 210 calories.* *Based on 130-pound personCalories In = Calories OutCHEESEBURGER20 Years

8、AgoToday333 caloriesHow many calories are in todays cheeseburger?Calorie Difference: 257 calories590 calories CHEESEBURGER20 Years AgoToday333 caloriesMaintaining a Healthy Weight is a Balancing ActCalories In = Calories OutHow long will you have to lift weights in order to burn the extra 257 calori

9、es?* *Based on 130-pound personIf you lift weights for 1 hour and 30 minutes,you will burn approximately 257 calories.* *Based on 130-pound personCalories In = Calories OutSPAGHETTI AND MEATBALLS20 Years AgoToday500 calories1 cup spaghetti with sauce and 3 small meatballsHow many calories do you thi

10、nk are in todays portion of spaghetti and meatballs? Calorie Difference: 525 calories1,025 calories 2 cups of pasta with sauce and 3 large meatballs20 Years AgoToday500 calories1 cup spaghetti with sauce and 3 small meatballsSPAGHETTI AND MEATBALLSHow long will you have to houseclean in order to bur

11、n the extra 525 calories?* *Based on 130-pound personMaintaining a Healthy Weight is a Balancing ActCalories In = Calories Out *Based on 130-pound personIf you houseclean for 2 hours and 35 minutes, you will burn approximately 525 calories.* Calories In = Calories OutFRENCH FRIES 20 Years AgoToday21

12、0 Calories2.4 ounces How many calories are intodays portion of fries?610 Calories6.9 ouncesCalorie Difference: 400 Calories FRENCH FRIES 20 Years AgoToday210 Calories2.4 ounces How long will you have to walk leisurely in order to burn those extra 400 calories?* *Based on 160-pound personMaintaining

13、a Healthy Weight is a Balancing ActCalories In = Calories Out *Based on 160-pound personIf you walk leisurely for 1 hour and 10 minutes you will burn approximately 400 calories.* Calories In = Calories Out 85 Calories 6.5 ouncesHow many calories are in todays portion?SODA20 Years AgoTodayCalorie Dif

14、ference: 165 Calories 250 Calories 20 ounces 85 Calories 6.5 ouncesSODA20 Years AgoTodayHow long will you have to work in the garden to burn those extra calories?* *Based on 160-pound personMaintaining a Healthy Weight is a Balancing ActCalories In = Calories OutIf you work in the garden for 35 minu

15、tes, you will burn approximately 165 calories.* *Based on 160-pound personCalories In = Calories Out320 calories How many calories are in todays turkey sandwich?TURKEY SANDWICH20 Years AgoTodayCalorie Difference: 500 calories 820 calories 320 calories TURKEY SANDWICH20 Years AgoTodayHow long will yo

16、u have to ride a bike in order to burn those extra calories?* *Based on 160-pound personMaintaining a Healthy Weight is a Balancing ActCalories In = Calories Out *Based on 160-pound personIf you ride a bike for 1 hour and 25 minutes,you will burn approximately 500 calories.* Calories In = Calories O

17、ut第四節(jié) 發(fā)胖之謎為什么要吃那么多東西？“進(jìn)行信號(hào)”饑餓與食欲“停止信號(hào)”飽滿感“進(jìn)行信號(hào)”饑餓與食欲饑餓是一種對(duì)食物需求的生理反應(yīng)，是由作用于大腦尤其是下丘腦的化學(xué)信使觸發(fā)的。神經(jīng)遞質(zhì)神經(jīng)肽（NPY）就是一種這樣的信使。它可以強(qiáng)烈地刺激食欲。饑餓也同樣受到很多其他腦部化學(xué)物質(zhì)和其他因素的影響，包括血液中的營(yíng)養(yǎng)物成分，上次進(jìn)食的量及成分，日常飲食結(jié)構(gòu)，天氣等。食欲也可以促使人們進(jìn)食，但食欲可以是后天習(xí)得的。二者并存時(shí)，食欲會(huì)加強(qiáng)饑餓感，但即使沒(méi)有饑餓感人同樣會(huì)感到有食欲。影響食欲的因素包括：后天的喜好，反感和時(shí)間環(huán)境因素內(nèi)啡肽天生的食欲社會(huì)交流某些疾病某些藥物“停止信號(hào)”飽滿感進(jìn)食過(guò)程中到一

18、定時(shí)間，大腦會(huì)收到不同來(lái)源的信號(hào)，表面已攝入足夠的食物，這種情況稱為飽滿，它來(lái)自于胃腸道中存在的食物。當(dāng)胃部伸展時(shí)，它的神經(jīng)感受器會(huì)向腦部發(fā)出信號(hào)告知胃部已裝滿食物，從而促使人們停止進(jìn)食。大腦同樣可以探知在血液中流動(dòng)的被吸收的營(yíng)養(yǎng)物的信息，并釋放神經(jīng)遞質(zhì)，以抑制進(jìn)食。進(jìn)餐后，飽滿感會(huì)繼續(xù)抑制饑餓，并保持一段時(shí)間。選擇不同的食物會(huì)影響到飽滿感，一些食物可以使飽滿感維持更長(zhǎng)的時(shí)間。級(jí)聯(lián)調(diào)控：饑餓、食欲、飽足感遺傳與肥胖瘦身素遺傳與肥胖2. 褐色脂肪組織褐色脂肪組織白色脂肪組織遺傳與肥胖3. 調(diào)定點(diǎn)理論4. 酶作用理論5. 脂肪細(xì)胞數(shù)量理論人體可以以某種方式選擇一定的體重而且可以通過(guò)控制飲食活動(dòng)和激素活動(dòng)來(lái)保持這種體重。脂蛋白脂肪酶（LPL）可以調(diào)控脂肪的貯存與催化脂肪細(xì)胞貯存三脂酰甘油。LPL濃度越高，脂肪細(xì)胞月容易貯存脂肪，人體就越容易肥胖。人體脂肪的量反映了細(xì)胞的數(shù)量和大小。肥胖者的脂肪細(xì)胞較多，較大。肥胖者的脂肪細(xì)胞還含有較多的LPL，因此貯存脂肪的效率也更高。人的