臀部脂肪多有益健康?

People with fat in their thighs and backsides may live longer because the fat traps harmful fatty particles and actively secretes helpful compounds, according to a report published on Tuesday.

Many studies have shown that people who accumulate fat around the abdomen and stomach are more likely to die of heart disease and other causes than bottom-heavy people, but the reasons are not clear.

This may be because several different mechanisms are involved, said Konstantinos Manolopoulos of Britain's University of Oxford.

"It is the protective role of lower body, that is, gluteofemoral fat, that is striking," Manolopoulos wrote in the International journal of Obesity.

"The protective properties of the lower-body fat depot have been confirmed in many studies," he added.

Fat on the bottom and thighs appears to store excess fatty acids, said Manolopoulos, who reviewed published scientific studies for his report.

Pear-shaped people also appear to have lower levels of compounds called inflammatory cytokines -- signaling chemicals involved in the body's response to infection that also can play a role in heart disease and diabetes when they are inappropriately active.

Fat on the legs may also absorb fats from the diet, keeping them from overwhelming the body when people overeat, Manolopoulos said.

Cholesterol levels reflect a tricky balance between high density lipoprotein, the HDL or "good" cholesterol that removes harmful fats from the blood, and low-density lipoprotein, the "bad" LDL cholesterol that can harden and block the arteries.

Fat in the thighs may also be more stable, he said, with studies showing abdominal fat breaks down quickly during fasting or stress, releasing potentially harmful components from the fat.

"The exact regulatory mechanisms of fatty acid release and storage and their effect on short- and long-term fatty acid metabolism remain to be analyzed," Manolopoulos wrote.

Leg fat may also be better at producing hormones such as leptin, which are made by fat and affect appetite and metabolism -- although Manolopoulos said this is poorly understood.

Understanding all this could lead to better drugs for treating obesity and related disease such as diabetes and heart disease, Manolopoulos said.
本週二發佈的一項報告稱，大腿和臀部脂肪較多的人可能更長壽，因爲脂肪能鎖住有害的脂肪顆粒，並可有效分泌出有益化合物。

很多研究表明，腹部脂肪多的人死於心臟病和其他疾病的可能性大於臀部脂肪多的人，但原因尚不清楚。

英國牛津大學的康斯坦第諾斯•馬諾洛波洛斯說，這可能是幾種不同機制共同作用的結果。

馬諾洛波洛斯在發表於《國際肥胖期刊》的研究報告中寫道：“下半身即臀部脂肪的保護性作用是驚人的。”

他說：“下半身脂肪的保護特性已在很多研究中得到驗證。”

馬諾洛波洛斯爲撰寫這份研究報告查閱了已發表的相關科學研究。他說，臀部和大腿的脂肪儲存了多餘的脂肪酸。

此外，“梨形”身材的人體內的一種叫做“炎性細胞因子”的化合物的含量似乎更低。這種信號性化學物質與身體對感染的反應有關，而且如果它們過於活躍，可能會導致心臟病和糖尿病。

馬諾洛波洛斯說，大腿上的脂肪可能還會吸收飲食中的脂肪，在人們吃得過飽時使它們不對身體造成過大的負擔。

膽固醇水平反映了高濃度脂蛋白和低濃度脂蛋白之間的一種複雜的平衡關係。高濃度脂蛋白是一種良性膽固醇，可清除血液中的有害脂肪；而低濃度脂蛋白是一種惡性膽固醇，會造成動脈硬化或堵塞。

馬諾洛波洛斯說，大腿上的脂肪也更加穩定，一些研究表明腹部脂肪可通過節食或壓力迅速化解，將潛在的有害化合物從脂肪中釋放出來。

馬諾洛波洛斯寫道：“脂肪酸釋放和存儲的具體調節機制以及它們對脂肪酸短期和長期代謝的影響仍有待分析。”

另外，腿部脂肪的燃燒更易產生瘦素等激素，瘦素由脂肪分泌，能夠影響食慾和新陳代謝，不過馬諾洛波洛斯說人們對其認識還不夠。

馬諾洛波洛斯說，瞭解這些知識能夠讓我們研製出更好的治療肥胖以及糖尿病和心臟病等相關疾病的藥物。

Vocabulary:

secrete: generate and separate from cells or bodily fluids 分泌

depot: a place where large amounts of food, goods or equipment are stored 貯藏處

metabolism: the chemical processes in living things that change food, etc. into energy and materials for growth 新陳代謝

leptin: a hormone produced by fat cells that helps regulate appetite and promotes normal insulin activity; leptin is under study as a treatment for lipodystrophy 瘦素