What Colour Is Your Fat?
中文譯版在後
We have all been brought up to think that fat in our body is not good. Stay lean and you are healthy. In fact, not all fats are created equal. Fats are classified in three colours: brown, white and beige.
When babies are born, they contain only brown fat. This fat exists in our shoulder blades, neck, along our spinal cord and above the collar bone. They can also wrap around our vital organs, and help turn food into heat for the body.
Brown fat has many small lipid droplets that contain mitochondria (energy generating organelles). They are rich in iron which explains why it turns brown – when this fat is exposed to oxygen, the iron in it turns it brown.
According to old biology, the brown fat will disappear and turn white when the baby grows up. However, this belief has been overturned by newer research and studies.
White fat cells are larger round cells with a single lipid droplet, and exist in our body’s connective tissues, usually beneath our skin (subcutaneous fat) and abdominal area (visceral fat). When we eat, white fat cells will convert excess energy into glucose, and excess is turned into lipid droplets, which are molecules called triglycerides. These molecules are signaling molecules that regulate our appetite and energy balance. When we are starving or need more energy, these droplets can be converted into fatty acids which in turn becomes energy and can be absorbed into our bloodstream.
Brown + White = ??
Then there is beige fat, which is a hybrid between brown and white, and is found in similar areas as white fat. The beauty of beige fat is that it can burn energy to produce heat (like brown fat). The “browning” effect of white fat cells can be achieved by exposure to low temperatures for a period of time (11℃ for women and 9℃ for men), good nutrients and exercise.
Changing Fat Types
Many researchers are aware that fat types can change from one form to another based on the triggers they are exposed to and the demands placed on where they are found. This can be done in one of two ways. TRANSdifferentiation is when a fat cell switches its corresponding gene. The second way is by firstly reversing a mature fat cell into its parental form (DEdifferentiation), then reprogramming its genes (REdifferentiation). In other words, once the fat turns beige, your body can burn more fat and you will lose weight! This can be achieved naturally.
It is well known that supplements can speed up the process of redifferentiation. Increase intake of supplements (from food ideally) rich in flavonoids resveratrol (found in pistachios, grapes blueberries, cranberries and cocoa) and quercetin (found in onions, green leafy vegetables, apples, grapes, berries, broccoli, green tea).
The body can also turn white fat into beige fat when the body is in a shivering condition for at least 2 hours. This method is probably not practical as you can only obtain desired results when this is repeated regularly.
Many studies have shown that brown / beige fat is associated with better health. Besides weight loss, there is also a decreased risk of hypothermia, as well as decrease risk of diabetes (as insulin sensitivity increases).
您的脂肪是什麼顏色？
現代人聽到「脂肪」二字都敬而遠之，它好像是健康身體、苗條身形的最大敵人，但其實不是所有脂肪都如斯恐怖。一般而言，我們可以把脂肪分成三種顏色作討論：棕色、白色和米色。
當嬰兒剛出生時，身體只有有棕色脂肪，這種脂肪存在於我們的肩胛骨、頸部、沿著脊柱周圍、頸骨上方等。它們用作包裹著我們的重要器官，幫助將食物轉化為熱量。
棕色脂肪由許多細小脂質滴組成，當中含有線粒體（產生能量的細胞器）。線粒體富含鐵質，而當其暴露於氧氣時，脂肪中的鐵質就會變成棕色。
根據舊生物學，當嬰兒長大後，棕色脂肪會消失並且會漸漸變白。但是這種觀念近年已被最新的研究推翻。
白色脂肪呈大圓形，由單個脂質滴組成，並存在於人體的結締組織中。這種脂肪一般會在我們的皮膚（皮下脂肪）和胸腔（內臟脂肪）下面。當我們進食時，白色脂肪細胞會將多餘的能量轉化為葡萄糖，然後再轉化為脂質小滴（或被稱為甘油三酸酯）的分子，而這些分子可以幫助調節食慾，調節能量平衡。當我們在飢餓狀態或需要更多能量時，這些脂質小滴就會轉化為脂肪酸，脂肪酸從而轉化為能量，經由血液吸收到身體中。
棕色+白色= ??
接下來就是米色脂肪， 它是棕色和白色脂肪的混合物，能夠在白色脂肪附近的區域發現。米色脂肪的可貴之處，在於它可以燃燒繼而以產生熱量（像棕色脂肪）。一般情況，只要吸收足夠營養、足夠運動鍛鍊，再加上在低溫的情況下（女性為11℃，男性為9℃），就可以讓白色脂肪細胞變成棕色。
改變脂肪類型
近年有許多研究人員都指出，脂肪的類型可以根據外界的觸發誘因和脂肪的存在環境，由一種形式轉變為另一種形式。這可以通過以下兩種方法來完成。第一種是分化轉移 (TRANSdifferentiation) ，轉換脂肪細胞到其相應的基因；第二種方法是先將成熟的脂肪細胞分化成其母體(Dedifferentiation)，然後重新編程基因(REdifferentiation)。因此，脂肪變成米色的過程，您的身體就會不斷燃燒脂肪，換句話說，減肥減重！而這個過程甚至是自然地運行起來呢。
一般來說，部分補充品可以加快細胞分化的過程，例如補充富含黃酮類白藜蘆醇（開心果、葡萄、藍莓、蔓越莓、可可……）和槲皮素（洋蔥、綠葉蔬菜、蘋果、葡萄、各種莓類、西蘭花、綠茶……）的營養，如果能直接由食物中吸收，效果則會更好。此外，當身體不停抖動多於2小時，也會將白色脂肪轉化成米色脂肪，可是這個方法卻有點不切實際，因為只有定期重複才能獲得所需的結果。
許多研究亦顯示，棕色和米色脂肪與健康有著正面關係。除了減肥以外，還可以降低患低溫症的風險，也會因胰島素敏感度的提高，而降低糖尿病的機會。