neuron stucture

Your brain is made of approximately 100 billion nerve cells, called neurons. Neurons have the amazing ability to gather and transmit electrochemical signals -- they are something like the gates and wires in a computer. Neurons share the same characteristics and have the same parts as other cells, but the electrochemical aspect lets them transmit signals over long distances (up to several feet or a few meters) and pass messages to each other.
Neurons have three basic parts:
Cell body - This main part has all of the necessary components of the cell, such as the nucleus (contains DNA), endoplasmic reticulum and ribosomes (for building proteins) and mitochondria (for making energy). If the cell body dies, the neuron dies.
Axon - This long, cable-like projection of the cell carries the electrochemical message (nerve impulse or action potential) along the length of the cell.
Depending upon the type of neuron, axons can be covered with a thin layer of myelin, like an insulated electrical wire. Myelin is made of fat, and it helps to speed transmission of a nerve impulse down a long axon. Myelinated neurons are typically found in the peripheral nerves (sensory and motor neurons), while non-myelinated neurons are found in the brain and spinal cord.
Dendrites or nerve endings - These small, branch-like projections of the cell make connections to other cells and allow the neuron to talk with other cells or perceive the environment. Dendrites can be located on one or both ends of the cell.

坐磁波椅治尿失禁 署東引進

【聯合報╱記者李蕙君／台東報導】
2009.07.27 03:02 am

署立台東醫院最近發表引進台東縣第一台座椅式體外磁波治療儀改善尿失禁，有效率達八成；該院泌尿科主任許維愷表示，最快2周至3周就有明顯效果，患者只要坐著治療，使用4次至6次、每次20分鐘，相當輕鬆。
許維愷表示，尿失禁有滿溢性、應力性、急迫性三類型，東西方體質不同，台灣人最常見為應力性尿失禁，只要咳嗽、打噴涕、突然站起來或大笑等腹壓增加，小便就不自主流出，應力性、急迫性都是可改善的症狀。
他說，目前常用的治療方式有藥物治療、凱格爾復健運動、電刺激搭配生理回饋儀、外科手術的矯正、座椅式體外磁波治療儀。
但藥物須長期服用，會引發口乾、便秘等體質差異上的副作用；凱格爾復健若認真做可達八成效果，但要長期做，持續性者不多；電刺激效果快速，且是侵入性治療，需要把探頭放到陰道或肛門內刺激，接受度低，健保也不給付；外科手術不適用所有病患，有手術風險且會復發。
座椅式體外磁波治療儀在台8年，目前是最夯的治療儀式，患者只要坐著20分鐘，看看報紙、電視等，很快就完成治療，該治療有健保給付，沒有任何已知的副作用，最快2周即見效果。老一輩患者都認為這種療效很好，願意回診治療。
【2009/07/27 聯合報】@ http://udn.com/

別忽略反式脂肪所佔據的細胞膜拖累您 !

反式脂肪吃下去馬上傷害肝臟 會破壞人體細胞膜代謝　

大明的阿姨八年前全家移民南非 , 媽媽為了讓大明和 妹妹 學英文、熟悉外國環境 , 每年暑假 , 總是讓他們到南非找阿姨。阿姨很喜歡這 2 個外甥 , 所以每天都把他們餵的飽飽的。 大明與 妹妹 剛從南非回來時 , 各胖了 3、 4 公斤 , 媽媽趕緊帶著兩兄妹來給我看診。看診的原因不是因為變胖 , 而是鼻子過敏的問題越來越嚴重 , 無時無刻都必須張口呼吸、鼻子已經完全不通了。 不但如此 , 大明的注 意力也很不集中 , 記憶力很差 , 一個月可以丟掉 3 把鑰匙 , 上課也 常被 老師點名。一問之下 , 我發現大明與 妹妹 都偏好奶製品 , 尤其是人造奶油。在南非的 2 個月 , 大明每天喝 2 大杯牛奶、幾條小乳酪 , 還喜歡在烤麵包上塗人造奶油、熱騰騰的馬鈴薯切開、加一塊人造奶油。回到台灣後 , 大明還常叮嚀媽媽要多買一些人造奶油 , 因為阿姨說人造奶油是植物油 , 對身體很好 !?

近二、三十年來 , 有越來越多的台灣人 , 受到西方飲食影響 , 以烤麵包加奶油當早餐 , 而且聽說奶油很不好 , 就改吃人造奶油。長期下來日積月累的結果 , 造成很多問題 , 例如高血壓、高血脂、心臟病、中風、各類過敏、自體免疫疾病、免疫力下降、肥胖 .....等等。

反式脂肪 / 氫化植物油是健康殺手

所謂「氫化」, 就是把植物油變成反式脂肪的過程 , 大家常吃的「人造奶油」, 就是氫化過的油。 人造奶油的製作方法 , 是在每個植物油分子理加 2 個氫原子 , 使原本順式脂肪酸變成反式脂肪酸。反式脂肪酸由於分子的極性較大 , 油分子之間的互相吸引力較強 , 所以在常溫下是固態 , 相當穩定。而原本的大豆油、玉米油這些植物油 , 在常溫下比較不穩定 , 呈液態。這就像變魔術一樣 , 液態的植物油 , 加了2 個氫之後 , 就變成固態的氫化植物油 , 然後再加點調味料 , 人工香料與色素 , 味道與模樣就跟奶油一樣了。 大家最耳熟能詳的人造奶油就是乳瑪琳。從 30 年前開始 , 台灣人就很盛行吃乳瑪琳 , 至今仍歷久不衰 , 例如 : 三明治 .... 等。另外一種氫化植物油 , 大家比較沒聽說 , 但卻更常吃 , 那就是植物性酥油 ( 俗稱白油 )。酥油是麵包師傅做麵包或餅乾時 , 幾乎都會加的油 , 以前多半是用豬油 , 現在幾乎全都用氫化植物油作成的酥油。常見如麵包、蛋糕、甜甜圈、冰淇淋等 ....及各地名產太陽餅、鳳梨酥、蛋黃酥、方塊酥、麻糬、月餅、喜餅 ...... 等等加工食品。

除此之外 , 由於氫化油不易敗壞 , 可重覆高溫油炸 , 成本低 , 使食物酥脆、賣相好 , 這種油料理時特別香 , 有很多業者都使用氫化油來油炸食物 , 例如 : 炸雞、薯條、洋芋片、餅乾、巧克力、蘇打餅、爆米花、油條、臭豆腐、鹽酥雞和素料 , 還有便利商店、大賣場架上的零食 .... 等等。要小心了 ! 您可能也在不知不覺中 , 吃下了對健康有害的氫化油。

(圖)反式脂肪問題嚴重被忽略

由於反式脂肪酸對身體的影響並非立即產生，因此人造奶油的問題一直被忽略。美國食品藥物管理局 ( FDA ) 直到 2006 年才強制要求食品包裝上必須標示反式脂肪的量，並規定反式脂肪酸限量 2 ％。然而即使是少量，對人體也可能有害。( 紐約禁用反式脂肪 2007 年七月起分階段實施 ) TIME < 時代 > 雜誌就曾公佈過 , 這種油在自然界是不存在的 , 也就是說在自然的情況下 , 人體是無法處理消化這種油脂的。 一吃下去馬上對肝臟產生傷害 , 而且還會破壞人體細胞膜，造成細胞的缺陷，影響未來的複製與再生。 當細胞膜受損或破洞時 , 細胞膜的功能就會異常無法進行「選擇性的滲透壓」, 使好的營養和氧氣滲入 , 細胞內新陳代謝的廢物排出。許多慢性病都與細胞膜不穩定有關 , 例如 : 皮膚過敏、鼻子過敏、氣喘、腸胃過敏、內分泌失調、視網膜病變、癌症 .... 等等。 巴維德 博士的油脂理論最堅持的就在此 , 她強調細胞膜不可受氫化植物油包圍缺氧而窒息 ( 癌症造成的原因之)。 脂肪酸是人體用來建造細胞膜與荷爾蒙的材料，反式脂肪酸卻是經人為氫化處理後才產生，不存在於自然界，因此人體無法處理這種油脂，只能任由其堆積於體內，進而增加罹患心臟血管疾病的機率。最近研究發現 , 氫化植物油比動物性脂肪更糟 , 會使血中壞的膽固醇增加 , 好的膽固醇減少 , 造成血管阻塞。

(圖)孕期營養影響寶寶未來的健康和家庭日後生活品質

加拿大政府健康部門於 1992 年曾做過一個實驗 , 將母奶收集起來化驗 , 發現其中有高達 7 . 2 % 的成分是反式脂肪酸 , 這表示母親本身吃了很多人造奶油、糕餅或其他氫化油。試想 , 母奶中有 7 % 是根本不能吃的氫化油 , 多麼恐怖 ! 也難怪現在有那麼多小朋友從小就有一大堆毛病。

(圖)有些幼稚園會遇怪現象--家長會問沒有在麥當勞辦生日餐會

另外 , 美國解剖各個年齡層的意外身亡者發現 , 由於從小就吃不該吃的東西 , 2 歲兒童已經開始有脂肪紋 ( Fatty Streaks ) 的現象。要知道 , 血管壁本來本來應該是光滑的 , 可是現代很多小孩的血管壁卻已經有脂肪紋 , 使血小板與壞膽固醇開始堆積 , 形成硬化斑塊 , 難怪中風年齡層會越來越低。過去 , 美國的研究向來認為油脂攝取越多 , 癌症罹患率越高 , 近幾年用更精確的統計分析 , 確進一步發現 , 原來是氫化植物油吃越多 , 癌症罹患率越高。

(圖)90% 血液在毛細血管 也要重視血液和血管的健康管理

而在台灣 , 從相關政府機構、食品加工廠、麵包糕餅店、速食店、西餐廳、一般餐廳、飯店、傳統早餐店、路邊的小販 ..... 到消費者 , 更不知道反式脂肪 ( 氫化植物油 ) 對健康有多大的影響 , 種種現象實在令人相當憂心。

反式脂肪與過敏 反是脂肪酸會造成的眾多問題 , 其中之一就是皮膚過敏。西醫對皮膚過敏沒什麼好辦法 , 只能擦類固醇或吃類固醇 , 但症狀壓下去了 , 過一陣子又發作 , 而且比上一次更嚴重。擦過類固醇的皮膚和原來的皮膚不一樣 , 照到陽光或接觸到冷熱水的反應 , 與健康皮膚大不相同 , 因此 , 自然醫學博士 陳俊旭 醫師相當反對使用類固醇。 自然醫學 陳俊旭 博士說 : 「臨床上 , 我看過太多皮膚過敏的案例。在美國時 , 我看過好幾個 [ 體無完膚 ] 的小朋友 , 全身包的密不通風 , 被小兒科醫師轉診過來 , 因為西醫已經拿他們沒辦法了。在我的觀念裡 , 皮膚過敏其實是皮膚裡面有毒素 ( 或心理壓抑 ) , 而反式脂肪就是毒素的一種。」
「皮膚裡的毒首先會讓人發癢 , 如果體內毒素累積太多 , 皮膚甚至會流汁、起疹塊或結疤。自然醫學治療皮膚過敏的原則是 , 體內與體外都要排毒 , 身心內外清爽 , 過敏就好了。」 從細胞的微觀層次來看 , 吃了壞油的人 , 它的細胞膜就是用比較多的壞油所構成 , 所以細胞膜比較不穩定 , 就容易啟動過敏反應 , 產生紅腫、流汁等現象。總之 , 不論是皮膚過敏、鼻子過敏、慢性中耳炎、氣喘 .... 等哪一種過敏 , 它們在細胞分子層面的機制都是很類似的 , 而避開毒素或避開過敏原都是最基本的方法。

(圖)氫化油或氧化油容易堵住皮脂腺形成皮膚乾燥或青春痘。

現在開始擁不嫌遲
脫胎換骨要 7 年

看到這裡 , 也許讀者會心生恐慌 , 心想已經吃這麼多年了 , 還有救嗎 ? 當然有 , 只要現在開始吃好油 , 然後逐漸把細胞膜壞油淘汰代謝掉就可以了。因為我們身體的細胞組織器官 , 一直持續著一進一出不斷新陳代謝的活動 , 今天身上這一層表皮 , 一個月後就換另一層皮了。表皮細胞代謝的週期是一個月 , 有的組織代謝比較慢 , 人體全身的細胞更新需 7 年的時間。 也就是說 , 如果原本身體不好、體質不佳、甚至罹患了癌症 , 只要有心改善 , 並能持之以恆的話 , 最晚 7 年的時間就可以脫胎換骨 , 把體質調好。

常規醫學能與不能

常規醫學治療不好的，您找他們幹什麼呢？
所以我們推薦ANDREW WEIL的書，痊癒之鑰在自己（已更名為自癒力）。YAHOO網站中另類醫學的部份就是他在負責的。他是哈佛醫學院畢業的，畢業後他到醫院去實習，發現那不是他所認知的醫學，自己還跑到了雅馬遜河流域去找古老的醫術，後來在他家的附近遇到了一位70幾歲的整骨醫師，那位老醫生家門前每天都門庭若市。他只靠幫人家調調骨頭，很多人氣喘、感冒都好了。這本痊癒之鑰在自己是ANDREW WEIL的第一本書。 裡面提到常規醫學能的和常規醫所不能的，也就是常規之學的長處和常規醫所不能醫治的。像所謂的外科系統、復健等是常規醫學的長處。而像濾過性病毒、慢性退化性疾病、大多數心理疾病自體免疫疾病或大部份的癌症，這些就是常規醫學治療不好的，那治療不好找他們幹什麼呢？

人生41歲壽命
現在的人平均壽命比較長，是因為嬰身么折的人數減少，而老一輩的人也還沒死光
我要問各位，癌症與飲食的關係這麼密切，那我們所蒐集到的資料有多少呢？像日本人就不一樣，所以他們提出來人生41歲壽命，不要說我們現在的人平均壽命比較長，那是因為嬰身么折的人數減少，而老一輩的人也還沒死光。您們可以去看看週遭的人或報紙上很多40-50歲的人是不是都有癌症，尤其是那些常常應酬的人，如歌星、影星啊，是不是？在日本有一個西丸正哉的人，他精通天文地理，研究食生態學，他認為古時候和我們現在人生理上並沒有相差很大，但古時候的人吃飯前先要去打獵，如果沒有打到，也只有摸摸肚子過一餐，即使到了農業社會，也是要先下田耕種，所以基本上古時的人是不是先運動才吃飯；而我們現在的人三頓不夠、四頓、五頓，吃完以後呢，像死屍一樣躺在那邊，所以我們在行為上是有偏差的。

小孩子年紀輕輕的也得癌症
台灣與日本差不多
如果日本社會由1959年起算，日本人的平均壽命只有41歲，因為日本在1959年，民國48年開始由歐美引進西方速食。果不其然，不要看日本，就看看我們台灣，那些得癌症的都是七老八十嗎？50歲的得，40歲的得連那些小孩子年紀輕輕的也得！！

現代化骨水
小心您小孩的骨頭腐蝕掉了
您們吃漢堡，旁邊配什麼，是不是喝可樂？陽明醫學院作了一個實驗，把蟑螂放入可樂中，經過一個禮拜，蟑螂屍體無存只剩下兩個趐膀，中興國小就拿這個來教育小孩子要多喝白開水，少喝碳酸飲料。像這個陽明大學作的實驗也不是什麼野雞大學，有沒有人告訴您們啊，沒有啊。可樂的PH值是2.2比工研醋2.4還酸。汽水、及其它的碳酸飲料是2.8，商人加了一些糖，然後給您的小孩子喝。您們知不知道可樂是用來洗豬腸的，一洗就脫了一層黏膜，那您們的小孩喝了是不是腸子也會如此。在小說裡的化骨水，就是這種，它會把人的骨頭都腐蝕掉了。是不是很像啊，對不對？
所以現在的小孩子不是營養好，是營養失調喔

更年期一定要吃荷爾蒙？
美國婦女一半在過世時是沒有子宮的
很多婦女到了更年期，就被告誡說要吃荷爾蒙，說什麼不吃會得骨質疏鬆症、糖尿病。但很多荷爾蒙的攝取造成了乳癌、子宮癌罹患率增加，所以婦女們真得是進退兩難。那我們來想想更年期少了什麼？是不是少了月經，也就是說少了一個排毒的管道，那妳還大魚大肉的往自己的血管裡面倒當然會不舒服，如果妳們吃改變得清淡一點，負擔較輕，根本不需要這些什麼荷爾蒙。尤其在美國，他們的醫學教育是怎麼教的，他們認為婦女的子宮在生完小孩以後，害怕子宮會長腫瘤，所以他們就千方百計地建議美國婦女把它拿掉。是這樣子的嗎？子宮一定會長癌症嗎？為什麼古時候的的婦女不會？就是因為這樣錯誤的教育，讓美國婦女一半在過世時是沒有子宮的。

疾病的死亡率和動物性油脂的消耗量成正比
幾十年前就已經知道了，台灣現在才知道
第一次世界大戰丹麥的進口完全的被聯軍封鎖，第二次世界大戰挪威的進口也被封鎖。當時是與循環系統疾病的死亡率戲劇性地降低了很多，此一結果使科學家們大為驚異。從圖中你們可以很清楚的看出疾病的死亡率和動物性油脂的消耗量成正比, 這個資料在幾10年前就已經知道了，我們台灣現在才知道飲食和癌症的關係。

病癥三步曲

第一步－不平衡 以均衡自然飲食調整
第二步－堆積及分泌 以飲食+內在清除法調整
第三步－內在疾病形成 以飲食+清除+心理靈性修持調整

疾病形成都有它的徵兆的。仔細看看您的位置在那裡。是在第一階段、第二階段或則是第三階段。古時有句話『引繩額而決之，其決必有處』意思是將繩子一直拉一直拉到它斷裂，它一定是會在某處斷裂的，但不確定會在什麼地方。這個故事給我們一些啟示：我們不要將我們的身體當作繩子一樣，一直給它壓力；否則它終究會有斷裂生病的一天，但我們卻不知它會生在何處；最好在繩子未斷裂之前緩緩的將它的壓力舒解掉，讓它保有最佳的彈性，以因應未來不可知的壓力。

若你檢視您自己，您的皮膚像嬰兒一樣細夕嫩夕、白裡透紅，那恭喜您！！表示您很健康，如果有其中現象也沒關係，因為當您在看這些資料時，表示一切都不會太晚。現在就慢慢讓我們仔細檢視一下：

病癥第一階段
不平衡現象

1.中度疲倦感
2.精神緊張、健忘、頭腦不清楚、無法自我放鬆
3.頭痛、肌肉緊張、局部麻木、抽痛、臠縮
4.食量突然增加、腸胃消化不良、特別喜歡甜食、高鈉
5.全身或局部發癢
6.有時候咳嗽或打噴涕
7.自感往來朝熱、朝紅或畏寒
8.易出意外狀況、不安感、挫折感、心情鬱悶
9.體重不正常增加

病癥第二階段
不正常堆積及分泌

1.呼吸時有異味、身體有異味（體臭）、口苦咽乾
2.鼻竇充血腫脹、反復咳喇打噴涕，經常感冒氣喘
3.皮膚呈現乾燥或多油膩、易起紅疹、過敏
4.身體過熱、容易出汗、手足潮濕
5.打嗝脹氣、便秘、腹瀉、嘔吐
6.女性月經痛、陰道分泌物異常、反復不斷發炎
7.反復頭痛、肌肉關節、脊柱、僵硬疼痛、慢性背痛
8.頻尿（尿色淺淡）、乏尿（尿色深紅）、刺痛、四肢腫脹
9.嚴重焦慮、恐懼、易怒、情緒不穩定、狂鬧
10.肥胖、高血脂、高血壓、高尿酸、血糖偏高
11.易出意外
12.夜臥不安寧

病癥第三階段
內在疾病形成

1.慢性消化不良、飲食不正常、進食困難、潰瘍
2.關節炎、骨質疏鬆症、痛風、退化性關節炎
3.偏頭痛、長期習慣性頭痛
4.白內障、聽力障礙、記憶力喪失
5.失眠、精神萎靡不振
6.不孕症、性生活障礙
7.糖尿病
8.持續性感染、發作
9.躁鬱症、歇斯底里症、精神分裂症
10.癌症（各種癌病變）
11.心臟血管疾病（心肌梗塞、腦中風、高血壓）
12.其他退化性疾病、免疫系統疾病、不明熱
13.成藥影響肝臟及腎臟的病變

中醫的秘訣

減少酸性的食物的攝取
那什麼是所謂的酸性食物，牛排、水煮蛋、乳酪..等都是，而鹹性的是那一些，蔬菜、水果..等都是（新世紀飲食P199）。您們去看中醫時，中醫給的是不是都是草葯（鹹性），而且是不是吩咐您們要禁口啊，那該禁的是什麼？應不是只有那一些生冷的白蘿蔔而已，應該禁的是那一些酸性的食物。

「化學蛋」
蛋是被過度誇張的食物
蛋是被過度誇張的食物，它的膽固醇相當的高。而且您們去看看現在的蛋黃是什麼顏色？是慘白的。您們可以拿去跟那些有機飼養出來的蛋比較看看，現在的蛋應該叫作「化學蛋」。（新世紀飲食P211）

吃馬鈴薯也會胖嗎？
那一些才是真正低油脂的食物
即然油脂影響我們這麼厲害，那一些才是真正低油脂的食物（新世紀飲食P260）？這裡我要提的是，您們有沒有看到「低脂牛奶」，不要被它騙了。它應該算是中油脂的食物，您們喝牛奶，照樣得心臟病、照樣得糖尿病。我們人油脂的攝取量應限定在20％以內，也就是每天20-25公克以內。那有人說吃馬鈴薯也會胖？那應該是您們吃的是炸過的馬鈴薯吧！！

「魚生火、肉生痰」
吃豆腐還不夠，還要吃個油豆腐
那一些是油脂百分之20以下的食物？基本上是青菜、水果。但並非所有的豆類都是。所以您們看我們吃豆腐還不夠，還要吃個油豆腐！另外魚也是不能天天吃，因為魚的油脂相當高。
在中醫治癌八法裡有提到「魚生火、肉生痰」，依照科學的眼光來看，我們的肝臟並不是處理油脂的地方，所以當您吃油脂較多的是不是馬上肝臟就受傷了，火氣馬上就大了。而瘦肉也是高油脂的食物，所以您們回家看媽媽水煮瘦肉是，上面是不是也浮著一層油。

顯著的平行模式
肉消耗的越多，則腸癌與心臟病的人數也越多
在1976年有一份報導，寫出了肉類與癌症的真正關係（新世紀飲食P258）。每人每年的肉消耗量與腸癌與心臟病的人數有一個很顯著的平行模式，肉消耗的越多，則腸癌與心臟病的人數也越多；也就是說，如果您們不改變飲食，還這樣大魚大肉。幸運的可以死於心臟病、心血管疾病，不然就會死於癌症。我的外公就是這樣的一個例子，本來以為是心血管疾病，後來到醫院檢查，結果是肺癌第三期。到了醫院治療時，全身都是管子，他自己覺得太痛苦，只好自己把管子拔掉。那我們回過頭來看看我們的小孩子，是不是很多現在的小孩子都不喜歡吃青菜。如果我們父母不把他們的習慣改過來，那他們以後會不會很慘啊？我怕現在吃得進去，以後他們吐不出來。

The staging of a carcinoma has to do with the size of the tumor, and the degree to which it has penetrated. When the tumor is small and has not penetrated the mucosal layer, it is said to be stage I cancer. Stage II tumors are into the muscle wall, and stage III involves nearby lymph nodes. The rare stage IV cancer has spread (metastasized) to remote organs.

The barium enema is a valuable diagnostic tool that helps detect abnormalities in the large intestine (colon). The barium enema, along with colonoscopy, remain standards in the diagnosis of colon cancer, ulcerative colitis, and other diseases of the colon.

tests for colon cancer

There are 4 basic tests for colon cancer: a stool test (to check for blood); sigmoidoscopy (inspection of the lower colon; colonoscopy (inspection of the entire colon); and double contrast barium enema. All 4 are effective in catching cancers in the early stages, when treatment is most beneficial.

How Fat Cells Work

A little more than half of the adults in the United States are overweight. Statistics show that an incredible 65.2 percent of the U.S. population is considered to be "overweight" or "obese." According to the Centers for Disease Control and Prevention (CDC), obesity and overweight status is determined in adults by finding a person's "Body Mass Index" or BMI.

BMI is a calculation that takes into consideration both a person's body weight and height to determine whether they are underweight, overweight or at a healthy weight. An adult who is considered "overweight" has a BMI somewhere between 25 and 29.9. An adult with a BMI of at least 30 is considered "obese." This measurement is used because it's typically a good indicator of body fat.

Whether due to concern for related health risks (high blood pressure, heart disease, diabetes, sleep apnea, respiratory problems, etc.), or just for sheer aesthetics, many Americans worry about fat. In fact, at this very moment, thousands of Americans are exercising or dieting to reduce their amount of body fat. But have you ever wondered what fat is? When a person "gets fat" -- gains weight -- what is actually happening inside the person's body? What are "fat cells" and how do they work?

Fat, or adipose tissue, is found in several places in your body. Generally, fat is found underneath your skin (subcutaneous fat). There's also some on top of each of your kidneys. In addition to fat tissue, some fat is stored in the liver, and an even smaller amount in muscle.

Where fat is concentrated in your body depends upon whet her you are a man or woman:

An adult man tends to carry body fat in his chest, abdomen and buttocks, producing an "apple" shape.

An adult woman tends to carry fat in her breasts, hips, waist and buttocks, creating a "pear" shape.

The difference in fat location comes from the sex hormones estrogen and testosterone. Fat cells are formed in the developing fetus during the third trimester of pregnancy, and later at the onset of puberty, when the sex hormones "kick in." It is during puberty that the differences in fat distribution between men and women begin to take form. One amazing fact is that fat cells generally do not generate after puberty -- as your body stores more fat, the number of fat cells remains the same. Each fat cell simply gets bigger! (There are two exceptions: the body might produce more fat cells if an adult gains a significant amount of weight or has liposuction performed.)

In this article, we will look at how fat cells store fat and how they get rid of it. See the next page to learn more.

Body Fat Basics

The human body contains two types of fat tissue:

White fat is important in energy metabolism, heat insulation and mechanical cushioning.

Brown fat is found mostly in newborn babies, between the shoulders, and is important for thermogenesis (making heat). Since adult humans have little to no brown fat, we'll concentrate on white fat in this article. See the bottom of this page for more on brown fat.

Fat tissue is made up of fat cells, which are a unique type of cell. You can think of a fat cell as a tiny plastic bag that holds a drop of fat. White fat cells are large cells that have very little cytoplasm, only 15 percent cell volume, a small nucleus and one large fat droplet that makes up 85 percent of cell volume.

How Fat Enters Your Body

When you eat food that contains fat, mostly triglycerides, it goes through your stomach and intestines. In the intestines, the following happens:

1.Large fat droplets get mixed with bile salts from the gall bladder in a process called emulsification. The mixture breaks up the large droplets into several smaller droplets called micelles, increasing the fat's surface area.

2.The pancreas secretes enzymes called lipases that attack the surface of each micelle and break the fats down into their parts, glycerol and fatty acids.

3.These parts get absorbed into the cells lining the intestine.

4.In the intestinal cell, the parts are reassembled into packages of fat molecules (triglycerides) with a protein coating called chylomicrons. The protein coating makes the fat dissolve more easily in water.

5.The chylomicrons are released into the lymphatic system -- they do not go directly into the bloodstream because they are too big to pass through the wall of the capillary.

6.The lymphatic system eventually merges with the veins, at which point the chylomicrons pass into the bloodstream.

You might be wondering why fat molecules get broken down into glycerol and fatty acids if they're just going to be rebuilt. This is because fat molecules are too big to easily cross cell membranes. So when passing from the intestine through the intestinal cells into the lymph, or when crossing any cell barrier, the fats must be broken down. But, when fats are being transported in the lymph or blood, it is better to have a few, large fat molecules than many smaller fatty acids, because the larger fats do not "attract" as many excess water molecules by osmosis as many smaller molecules would.

In the next section, we'll look at how fat is stored in your body.

Fat Storage

In the last section, we learned how fat in the body is broken down and rebuilt into chylomicrons, which enter the bloodstream by way of the lymphatic system.

Chylomicrons do not last long in the bloodstream -- only about eight minutes -- because enzymes called lipoprotein lipases break the fats into fatty acids. Lipoprotein lipases are found in the walls of blood vessels in fat tissue, muscle tissue and heart muscle.

Insulin

When you eat a candy bar or a meal, the presence of glucose, amino acids or fatty acids in the intestine stimulates the pancreas to secrete a hormone called insulin. Insulin acts on many cells in your body, especially those in the liver, muscle and fat tissue. Insulin tells the cells to do the following:

Absorb glucose, fatty acids and amino acids

Stop breaking down:

glucose, fatty acids and amino acids

glycogen into glucose

fats into fatty acids and glycerol

proteins into amino acids

Start building:

glycogen from glucose

fats (triglycerides) from glycerol and fatty acids

proteins from amino acids

The activity of lipoprotein lipases depends upon the levels of insulin in the body. If insulin is high, then the lipases are highly active; if insulin is low, the lipases are inactive.

The fatty acids are then absorbed from the blood into fat cells, muscle cells and liver cells. In these cells, under stimulation by insulin, fatty acids are made into fat molecules and stored as fat droplets.

It is also possible for fat cells to take up glucose and amino acids, which have been absorbed into the bloodstream after a meal, and convert those into fat molecules. The conversion of carbohydrates or protein into fat is 10 times less efficient than simply storing fat in a fat cell, but the body can do it. If you have 100 extra calories in fat (about 11 grams) floating in your bloodstream, fat cells can store it using only 2.5 calories of energy. On the other hand, if you have 100 extra calories in glucose (about 25 grams) floating in your bloodstream, it takes 23 calories of energy to convert the glucose into fat and then store it. Given a choice, a fat cell will grab the fat and store it rather than the carbohydrates because fat is so much easier to store.

Next, we'll look at how your body breaks down fat.

Breaking Down Fat

When you are not eating, your body is not absorbing food. If your body is not absorbing food, there is little insulin in the blood. However, your body is always using energy; and if you're not absorbing food, this energy must come from internal stores of complex carbohydrates, fats and proteins. Under these conditions, various organs in your body secrete hormones:

pancreas - glucagon

pituitary gland - growth hormone

pituitary gland - ACTH (adrenocorticotropic hormone)

adrenal gland - epinephrine (adrenaline)

thyroid gland - thyroid hormone

These hormones act on cells of the liver, muscle and fat tissue, and have the opposite effects of insulin.

When you are not eating, or you are exercising, your body must draw on its internal energy stores. Your body's prime source of energy is glucose. In fact, some cells in your body, such as brain cells, can get energy only from glucose.

The first line of defense in maintaining energy is to break down carbohydrates, or glycogen, into simple glucose molecules -- this process is called glycogenolysis. Next, your body breaks down fats into glycerol and fatty acids in the process of lipolysis. The fatty acids can then be broken down directly to get energy, or can be used to make glucose through a multi-step process called gluconeogenesis. In gluconeogenesis, amino acids can also be used to make glucose.

In the fat cell, other types of lipases work to break down fats into fatty acids and glycerol. These lipases are activated by various hormones, such as glucagon, epinephrine and growth hormone. The resulting glycerol and fatty acids are released into the blood, and travel to the liver through the bloodstream. Once in the liver, the glycerol and fatty acids can be either further broken down or used to make glucose.

Losing Weight and Losing Fat

Your weight is determined by the rate at which you store energy from the food that you eat, and the rate at which you use that energy. Remember that as your body breaks down fat, the number of fat cells remains the same; each fat cell simply gets smaller.

Most experts agree that the way to maintain a healthy weight is:

Eat a balanced diet - appropriate amounts of carbohydrates, fat and protein

Do not eat excessively - for most people, a diet of 1,500 to 2,000 calories a day is sufficient to maintain a healthy weight

Exercise regularly

For more information on fat and your health, check out the links on the following page.

Lots More Information

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How Body Mass Index Works

How Fats Work

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How Exercise Works

How Fat Vaccines Will Work

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Is a lack of sleep making me fat?

More Great Links

American Obesity Association

CDC: Overweight and Obesity

MedlinePlus: Weight Control

How Cholesterol Works

What is Cholesterol?

Cholesterol is a waxy, fat-like compound that belongs to a class of molecules called steroids. It's found in many foods, in your bloodstream and in all your body's cells. If you had a handful of cholesterol, it might feel like a soft, melted candle. Cholesterol is essential for:

1.Formation and maintenance of cell membranes (helps the cell to resist changes in temperature and protects and insulates nerve fibers)
2.Formation of sex hormones (progesterone, testosterone, estradiol, cortisol)
3.Production of bile salts, which help to digest food
4.Conversion into vitamin D in the skin when exposed to sunlight.

The formation of cholesterol involves a series of complicated biochemical reactions that begin with the widespread 2-carbon molecule Acetyl CoA: Acetyl CoA (C2) --> mevalonate (C6) --> isopentenyl pyrophosphate (C5) --> squalene (C30) --> cholesterol (C27).

Cholesterol is made primarily in your liver (about 1,000 milligrams a day), but it is also created by cells lining the small intestine and by individual cells in the body.

Blood Cholesterol vs. Dietary Cholesterol

It may surprise you to know that our bodies make all the cholesterol we need. When your doctor takes a blood test to measure your cholesterol level, the doctor is actually measuring the amount of circulating cholesterol in your blood, or your blood cholesterol level. About 85 percent of your blood cholesterol level is endogenous, which means it is produced by your body. The other 15 percent or so comes from an external source -- your diet. Your dietary cholesterol originates from meat, poultry, fish, seafood and dairy products. It's possible for some people to eat foods high in cholesterol and still have low blood cholesterol levels. Likewise, it's possible to eat foods low in cholesterol and have a high blood cholesterol level.

So, why is there so much talk about cholesterol in our diet? It's because the level of cholesterol already present in your blood can be increased by high consumption of cholesterol and saturated fat in your diet. This increase in dietary cholesterol has been associated with atherosclerosis, the build-up of plaques that can narrow or block blood vessels. (Think about what happens to your kitchen drain pipes when you pour chicken fat down the sink.) If the coronary arteries of the heart become blocked, a heart attack can occur. The blocked artery can also develop rough edges. This can cause plaques to break off and travel, obstructing blood vessels elsewhere in the body. A blocked blood vessel in the brain can trigger a stroke.

The average American man eats about 360 milligrams of cholesterol a day; the average woman eats between 220 and 260 milligrams daily. So how are we doing? The American Heart Association recommends that we limit our average daily cholesterol intake to less than 300 milligrams. Obviously, people with high levels of cholesterol in the blood should take in even less.

Good and Bad Cholesterol

Comments about "good" and "bad" cholesterol refer to the type of carrier molecule that transports the cholesterol. These carrier molecules are made of protein and are called apoproteins載脂蛋白. They are necessary because cholesterol and other fats (lipids) can't dissolve in water, which also means they can't dissolve in blood. When these apoproteins are joined with cholesterol, they form a compound called lipoproteins. The density of these lipoproteins is determined by the amount of protein in the molecule. "Bad" cholesterol is the low-density lipoprotein (LDL), the major cholesterol carrier in the blood. High levels of these LDLs are associated with atherosclerosis. "Good" cholesterol is the high-density lipoprotein (HDL); a greater level of HDL--think of this as drain cleaner you pour in the sink--is thought to provide some protection against artery blockage.

A high level of LDL in the blood may mean that cell membranes in the liver have reduced the number of LDL receptors due to increased amounts of cholesterol inside the cell. After a cell has used the cholesterol for its chemical needs and doesn't need any more, it reduces its number of LDL receptors. This enables LDL levels to accumulate in the blood. When this happens, the LDLs begin to deposit cholesterol on artery walls, forming thick plaques. In contrast, the HDLs--the "good" guys--act to remove this excess cholesterol and transport it to the liver for disposal.

A third group of carrier molecules, the very low-density lipoproteins (VLDL) are converted to LDL after delivering triglycerides to the muscles and adipose (fat) tissue.

The levels of HDL, LDL and total cholesterol are all indicators for atherosclerosis and heart attack risk. People who have a cholesterol level of 275 or greater (200 or less is desirable) are at significant risk for a heart attack, despite a favorable HDL level. In addition, people who have normal cholesterol levels but low HDL levels are also at increased risk for a heart attack.

Cholesterol Risk Factors

There are a number of factors that influence a person's cholesterol levels. They include diet, age, weight, gender, genetics, diseases and lifestyle.

Diet

There are two dietary factors associated with increases in blood cholesterol levels:

Eating foods that are high in saturated fats, even if the fats themselves do not contain cholesterol. (These include foods containing high levels of hydrogenated vegetable oils, especially palm and coconut oils, avocados and other high-fat foods of vegetable origin.)

Eating foods containing high levels of cholesterol. (This group includes eggs and red meat--the most maligned of the cholesterol culprits--as well as lard and shrimp. These foods can significantly raise blood cholesterol levels, especially when combined with foods that are high in saturated fat.)

It's important to note that only foods of animal origin contain cholesterol. Lack of awareness of this fact has led to some confusing labels at the grocery store. For example, some items that are high in saturated fats from plant sources bear labels claiming that they are 100 percent cholesterol free. The statement may be true, but it's generally misleading because it implies that the product is definitely beneficial to your health.

Age

The blood levels of cholesterol tend to increase as we age--a factor doctors consider when deciding treatment options for patients with certain cholesterol levels.

Weight

People who are overweight are more likely to have high blood cholesterol levels. They also tend to have lower HDL levels. The location of the excess weight also seems to play a role in cholesterol levels. A greater risk of increased cholesterol levels occurs when that extra weight is centered in the abdominal region, as opposed to the legs or buttocks.

Gender

Men tend to have higher LDL levels and lower HDL levels than do women, especially before age 50. After age 50, when women are in their post-menopausal years, decreasing amounts of estrogen are thought to cause the LDL level to rise.

Genetics

Some people are genetically predisposed to having high levels of cholesterol. A variety of minor genetic defects can lead to excessive production of LDLs or a decreased capacity for their removal. This tendency towards high cholesterol levels is often passed on from parents to their children. If your parents have high cholesterol, you need to be tested to see if your cholesterol levels are also elevated.

Diseases

Diseases such as diabetes can lower HDL levels, increase triglycerides and accelerate the development of atherosclerosis. High blood pressure, or hypertension, can also hasten the development of atherosclerosis, and some medications used to treat it can increase LDL and triglycerides and decrease HDL levels.

Lifestyle

Factors that negatively affect cholesterol levels also include high levels of stress, which can raise total cholesterol levels, and cigarette smoking, which can lower a person's HDL level as much as 15 percent. On the other hand, strenuous exercise can increase HDL levels and decrease LDL levels. Exercise also can help reduce body weight, which, in turn, can help reduce cholesterol. Recent research has shown that moderate alcohol use (one drink per day for women, two drinks a day for men) can raise HDL cholesterol and therefore reduce the risk of heart attack. Despite such research, it is difficult to recommend the habitual use of alcohol, because there are also negative health consequences associated with alcohol use and a high potential for abuse.

Always remember that risk factors for high cholesterol and cardiovascular disease don't exist in a vacuum--they tend to amplify each other. Reducing the risk of a cardiovascular disease involves eliminating all of the risk factors that we can control and seeking medical advise for those we can't.

Cholesterol Testing and Prevention

How often should I have my cholesterol levels tested?

You should get your cholesterol tested every three to five years, more often if you have high cholesterol levels. Please refer to the table below for guidelines for total cholesterol, LDL and HDL levels.

What can I do to reduce my cholesterol?

There are several steps you can take to reduce your cholesterol levels. The first is to eat a low-fat, low-cholesterol diet. That means keeping your total fat consumption--saturated, polyunsaturated and monounsaturated--to fewer than 30 percent of your daily intake of calories. (See How Fat Works for details.) Remember to keep your cholesterol intake to fewer than 300 milligrams per day. Saturated fats contained in butter, whole milk, hydrogenated oils, chocolate shortening, etc. should comprise no more than one third of your total fat consumption. To reduce your total fat and cholesterol intake, limit your consumption of meats such as beef, pork, liver and tongue (always trim away excess fat). In addition, avoid cheese, fried foods, nuts and cream, and try to curb your intake of eggs to no more than four per week. Try to eat meatless meals several times a week, use skim milk and include fish in your diet. Eat a wide variety of vegetables, pasta, grains and fruit. Another good tip is to look at the package label of the foods you buy, and restrict your choices to foods containing 3 grams of fat or less per serving.

There is evidence that water-soluble fibers can aid in lowering cholesterol; these foods include the fiber in oat or corn bran, beans and legumes, pectin found in apples and other fruits, and guar that is used as a thickener. Although highly touted by the media and health food stores, the phospholipid Lecithin has not been confirmed as a reducer of blood cholesterol levels.

If you are overweight, trying to lose weight and including aerobic exercise in your routine can help raise those desirable HDL levels. Diet and exercise alone can decrease cholesterol levels by up to 15 percent.

It probably comes as no surprise to you that, if you smoke, you should quit to avoid a wide range of health problems, including lower HDL levels and increased risk of heart attack.

Medicating High Cholesterol

Sometimes positive changes in diet, lifestyle and exercise are not enough. In these cases, doctors may consider the use of medication that lowers cholesterol. The decision to have a patient begin medication is often based on high levels of LDL cholesterol and other risk factors for cardiovascular disease. For example, medication may be indicated if your LDL level is over 190 or is over 160 and you have several other risk factors for cardiovascular disease.

Drugs that reduce LDL blood levels can prevent or reduce the build-up of artery-blocking plaques and can limit the possibility of the release of those plaques as dangerous blood clots. There are several types of drugs that can help reduce blood cholesterol levels. The most commonly prescribed are the statins, HMG-CoA reductase inhibitors, including:

Lovastatin (Mevacor)

Simvastatin (Zocor)

Atorvastatin (Lipitor), a new, highly potent drug

These drugs work within the liver to directly prevent the formation of cholesterol and can lower LDL cholesterol by as much as 40 percent. Research also shows that these drugs can reduce the risk of death from cardiovascular disease. Another major drug category is the resins, which bind bile acids, causing the liver to produce more of them and using up cholesterol in the process. By "tying" it up, these drugs make cholesterol less available in the blood. They include:

Cholestyramine (Questran)

Colestipol (Colestid)

The B vitamin Niacin, in high doses, can lower triglycerides and LDL levels and increase HDL levels. Niacin has been proven to reduce a person's risk of having a second heart attack. Last are the drugs in the fibrates category, which lower triglycerides and can increase HDL levels. These include:

Gemfibrozil (Lopid)

Fenofibrate (Tricor)

The decision to take cholesterol- or lipid-lowering drugs is not taken lightly by your doctor. These drugs can be fairly expensive and are often required for many years or even the rest of your life. It is also important to note that some of these drugs can have dangerous side effects, such as damage to the liver.

Adopting a healthy lifestyle and visiting your doctor regularly can help curb your risks of problem cholesterol. Have your cholesterol levels checked by a physician, rather than risk incorrectly interpreting numbers in self test kits currently on the market. Remember, cholesterol is necessary for life but it can also be very harmful and requires monitoring. So, watch your cholesterol and keep in mind that, for every 1 percent drop in your cholesterol level, your risk of heart attack is lowered by 2 percent.

For more information on cholesterol and related topics, check out the links on the next page.

Cholesterol: Lots More Information

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How Calories Work

Inside this Article
1. Introduction to How Calories Work
2. What is a Calorie?
3. What Calories Do
4. BMR
5. Your Caloric Needs
6. Calories, Fat and Exercise
7. Lots More Information
8. See all Weight Loss articles

For years now, calories have been all the rage -- people are counting them and cutti­ng them, and you'd be hard-pressed to find something at the supermarket that does not list its calories per serving somewhere on the package. But have you ever wondered what exactly a calorie is?
In this article, we'll find out what calories are and why we need them, and examine the relationship between calories and weight.

What is a Calorie?
A calorie is a unit of energy. We tend to associate calories with food, but they apply to anything containing energy. For example, a gallon (about 4 liters) of gasoline contains about 31,000,000 calories.
Specifically, a calorie is the amount of energy, or heat, it takes to raise the temperature of 1 gram of water 1 degree Celsius (1.8 degrees Fahrenheit). One calorie is equal to 4.184 joules, a common unit of energy used in the physical sciences.
Most of us think of calories in relation to food, as in "This can of soda has 200 calories." It turns out that the calories on a food package are actually kilocalories (1,000 calories = 1 kilocalorie). The word is sometimes capitalized to show the difference, but usually not. A food calorie contains 4,184 joules. A can of soda containing 200 food calories contains 200,000 regular calories, or 200 kilocalories. A gallon of gasoline contains 31,000 kilocalories.
The same applies to exercise -- when a fitness chart says you burn about 100 calories for every mile you jog, it means 100 kilocalories. For the duration of this article, when we say "calorie," we mean "kilocalorie."

Caloric Breakdown
· 1 g Carbohydrates: 4 calories
· 1 g Protein: 4 calories
· 1 g Fat: 9 calories

What Calories Do
Human beings need energy to survive -- to breathe, move, pump blood -- and they acquire this energy from food.
The number of calories in a food is a measure of how much potential energy that food possesses. A gram of carbohydrates has 4 calories, a gram of protein has 4 calories, and a gram of fat has 9 calories. Foods are a compilation of these three building blocks. So if you know how many carbohydrates, fats and proteins are in any given food, you know how many calories, or how much energy, that food contains.
If we look at the nutritional label on the back of a packet of maple-and-brown-sugar oatmeal, we find that it has 160 calories. This means that if we were to pour this oatmeal into a dish, set the oatmeal on fire and get it to burn completely (which is actually pretty tricky), the reaction would produce 160 kilocalories (remember: food calories are kilocalories) -- enough energy to raise the temperature of 160 kilograms of water 1 degree Celsius. If we look closer at the nutritional label, we see that our oatmeal has 2 grams of fat, 4 grams of protein and 32 grams of carbohydrates, producing a total of 162 calories (apparently, food manufacturers like to round down). Of these 162 calories, 18 come from fat (9 cal x 2 g), 16 come from protein (4 cal x 4 g) and 128 come from carbohydrates (4 cal x 32 g).
Our bodies "burn" the calories in the oatmeal through metabolic processes, by which enzymes break the carbohydrates into glucose and other sugars, the fats into glycerol and fatty acids and the proteins into amino acids (see How Food Works for details). These molecules are then transported through the bloodstream to the cells, where they are either absorbed for immediate use or sent on to the final stage of metabolism in which they are reacted with oxygen to release their stored energy.
Click here for a simplified diagram of these metabolic processes.

BMR
Just how many calories do our cells need to function well? The number is different for every person. You may notice on the nutritional labels of the foods you buy that the "percent daily values" are based on a 2,000 calorie diet -- 2,000 calories is a rough average of what a person needs to eat in a day, but your body might need more or less than 2,000 calories. Height, weight, gender, age and activity level all affect your caloric needs. There are three main factors involved in calculating how many calories your body needs per day:
· Basal metabolic rate
· Physical activity
· Thermic effect of food
Your basal metabolic rate (BMR) is the amount of energy your body needs to function at rest. This accounts for about 60 to 70 percent of calories burned in a day and includes the energy required to keep the heart beating, the lungs breathing, the kidneys functioning and the body temperature stabilized. In general, men have a higher BMR than women. One of the most accurate methods of estimating your basal metabolic rate is the Harris-Benedict formula:
· Adult male: 66 + (6.3 x body weight in lbs.) + (12.9 x height in inches) - (6.8 x age in years)
· Adult female: 655 + (4.3 x weight in lbs.) + (4.7 x height in inches) - (4.7 x age in years)
(Note: The first number in the equation for females is, in fact, 655. Strange but true.)

Your Caloric Needs
As you now know, there are three main factors involved in calculating how many calories your body needs per day: your BMR, physical activity and the thermic effect of food.
The second factor in the equation, physical activity, consumes the next highest number of calories. Physical activity includes everything from making your bed to jogging. Walking, lifting, bending, and just generally moving around burns calories, but the number of calories you burn in any given activity depends on your body weight. Click here for a great table listing the calories expended in various physical activities and for various weights.
The thermic effect of food is the final addition to the number of calories your body burns. This is the amount of energy your body uses to digest the food you eat -- it takes energy to break food down to its basic elements in order to be used by the body. To calculate the number of calories you expend in this process, multiply the total number of calories you eat in a day by 0.10, or 10 percent. If you need some help determining how many calories you eat in a day, check out these sites:
· USDA National Nutrient Database
· Food Data
· Mike's Calorie And Fat Gram Chart
The total number of calories a body needs in a day is the sum of these three calculations. If you only want a rough estimate of your daily caloric needs, you can skip the calculations and click here.

Calories, Fat and Exercise
So what happens if you take in more or fewer calories than your body burns? You either gain or lose fat, respectively. An accumulation of 3,500 extra calories is stored by your body as 1 pound of fat -- fat is the body's way of saving energy for a rainy day. If, on the other hand, you burn 3,500 more calories than you eat, whether by exercising more or eating less, your body converts 1 pound of its stored fat into energy to make up for the deficit.
One thing about exercise is that it raises your metabolic rate not only while you're huffing and puffing on the treadmill. Your metabolism takes a while to return to its normal pace. It continues to function at a higher level; your body burns an increased number of calories for about two hours after you've stopped exercising.
Lots of people wonder if it matters where their calories come from. At its most basic, if we eat exactly the number of calories that we burn and if we're only talking about weight, the answer is no -- a calorie is a calorie. A protein calorie is no different from a fat calorie -- they are simply units of energy. As long as you burn what you eat, you will maintain your weight; and as long as you burn more than you eat, you'll lose weight.
But if we're talking nutrition, it definitely matters where those calories originate. Carbohydrates and proteins are healthier sources of calories than fats. Although our bodies do need a certain amount of fat to function properly -- an adequate supply of fat allows your body to absorb the vitamins you ingest -- an excess of fat can have serious health consequences. The U.S. Food and Drug Administration recommends that a maximum of 30 percent of our daily calories come from fat. So, if you eat 2,000 calories a day, that's a maximum of 600 calories from fat, or 67 grams of fat, per day. However, many doctors and nutritionists now set the maximum number of fat calories at 25 percent of our daily caloric intake. That's 56 grams of fat per day for a 2,000 calorie diet.
Here are some calorie and fat contents that may surprise you:
For more information on calories, dieting, nutrition and related topics, check out the links on the next page!

Related HowStuffWorks Articles
· How Food Works
· How Fats Work
· How Fat Cells Work
· How Cholesterol Works
· How Exercise Works
· How Dieting Works
· How Diet Pills Work
· Does drinking ice water burn calories?
· How many calories does a person need daily?
· How can a diet pill make you feel full?
· Would a fat tax save lives?
· How Vegetarians Work
· How Vegans Work
More Great Links
· Nutrition Calculators
· CaloriesPerHour.com
· Food For Thought: An Interview with Nutrition Scientist Dr. Paul Saltman
· What a Set of Batteries!: A Commentary on the Origin and Use of Our Body's Energy
· Experiment: Measuring the Number of Calories in Sunlight - PDF

The human body is an amazing machine, and every once in a while it will do something to remind you that it's working hard to keep you alive and well. The stomach growl is one of these reminders. Loud, soft and sometimes for no good reason at all, your growling stomach has a lot to say.
Whether you call it grumbling, rumbling, gurgling or growling, from time to time everybody's belly chimes in. These noises might sound like they should be coming from a noisy pot of bubbling stew rather than your stomach.
­But the big question is, why does it growl in the first place? And why does your stomach seem to growl the moment a room grows quiet?

­Your stomach doesn't have such perfect timing or such a malicious sense of sabotage. But there is a perfectly logical explanation why your stomach sometimes feels the need to be heard.
Let's examine this age-old question on the next page and discover why Winnie the Pooh isn't the only one with a rumbly in his tumbly.

Causes of Stomach Growling
Stomach growling, which originates in the stomach and the small intestine, can be explained by a closer look at how the digestive system functions.

The digestive system is, in essence, a long tube that starts at the mouth and ends at the anus. This tube connects with the various organs and passages that play important roles in digestion. One of the most important things to know about the digestive system is the manner in which it propels food. Waves of muscle contractions move and push the contents continually downward in a process called peristalsis蠕動. In addition to moving your meal along its digestive path, these contractions also help churn food, liquid and different digestive juices together, rendering them into a gooey mix known as chyme.
Stomach growling is the result of this process. Moving with those solid and liquid chyme ingredients are gasses and air. As all these ingredients get pushed around and broken down into easy-to-absorb bits, pockets of air and gas also get squeezed and create the noises we hear. Stomach growling can happen at any time -- not just when you're hungry -- but if there's food in your stomach or small intestine, the growling becomes quieter. It's like putting a pair of sneakers in the dryer by themselves versus with a load of towels. The towels muffle the noise of the shoes as they bounce around.
But you may be wondering -- if your stomach is empty, why are the muscle contractions that digest food happening to begin with? The reason has to do with hunger and appetite. About two hours after your stomach empties itself, it begins to produce hormones that stimulate local nerves to send a message to the brain. The brain replies by signaling for the digestive muscles to restart the process of peristalsis. Two results occur: First, the contractions sweep up any remaining food that was missed the first time around. Second, the vibrations of an empty stomach make you hungry. Muscle contractions will come and go about every hour, generally lasting 10 to 20 minutes, until you eat again. Learn more about the twists and turns your food takes after your first bite by reading How the Digestive System Works.

Word Origins
The technical name for the noises made by a grumbling stomach is borborygmi (borborygmus 腹鳴is the singular form). The term comes from the Greek word borborugmos, an example of onomatopoeia擬聲調 (a word created to imitate a sound). Borborygmi illustrates what stomach growling might sound like in word form. Onomatopoeia is commonly used for animal sounds and other noises, and can differ between languages. Examples in the English language include bang, hiss, whisper and buzz.


In some cases, excessive gurgling and grumbling may be a sign of an upset stomach or a medical condition like irritable bowel syndrome. In these cases, there are usually a number of additional gastrointestinal complaints accompanying a growling stomach.
So now that we know what causes stomach growling, is there any way to control it? One tip to mute a noisy belly is to eat many small meals instead of a few large ones. Your digestive system will have less opportunity to create those peristalsis rumbles if your body has something tasty in it. Also, eating less gaseous foods may help decrease the growling.
So, is your body making any other weird noises? Visit the links on the next page to learn more about the human body.

Lots More Information
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How Calories Work
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How does your stomach keep from digesting itself?
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How Fats Work
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How The Digestive System Works
How Vegans Work
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Irritable Bowel Syndrome
More Great Links
Digestive Disorders Health Center
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