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.

    周二發表的一個報告稱，大腿和臀部肥胖的人可能更長壽，因為脂肪吸收了有害的油脂微粒并主動分泌出一種有益的混合物。

    許多研究也顯示，與下肢肥胖的人相比，腹部和胃部脂肪堆積容更易引起心臟病死亡，原因還不甚清楚。

    英國牛津大學的康斯坦丁。馬洛普洛斯說："這關系著幾種不同的機理。"

    馬洛普洛斯在國際肥胖期刊文章中寫到："下肢臀股的脂肪保護作用很顯著。"

    他還說："許多研究項已證實，下肢脂肪堆積有保護作用。"

    馬洛普洛斯在他的報告中，回顧了已發表的研究，研究顯示，臀部和大腿的脂肪能儲藏過多的脂肪酸。

    梨形體型的人體內感染細胞因子水平較低，這是一種人體對感染反映的化學信號，當他們不太活躍時，能有效對抗心臟病和糖尿病。

    馬洛普洛斯認為，腿部脂肪可以吸收人們日常飲食中過量攝取的脂肪。

    膽固醇水平在高密度的脂蛋白之間有一種微妙的平衡，HDL或"好"膽固醇能去除血液中的有害脂肪，低密度的"壞"脂蛋白能夠造成動脈血管變硬和堵塞。

    他說，大腿的脂肪更穩定，研究顯示，節食或有壓力時，腹部脂肪分解很快，會釋放出有害物質。

    馬洛普洛斯寫到："脂肪酸有節制的精確釋放和儲存，對長期或短期脂肪酸代謝的影響仍需進一步分析。"

    盡管馬洛普洛斯說人們對此知之甚少，腿部脂肪也能產生如瘦素，那是一種由脂肪產生的影響食欲和新陳代謝的荷爾蒙。

    馬洛普洛斯說，完全清楚以后，就能夠制造更好的減肥藥或治療相關疾病如糖尿病的藥。