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.
本周二发布的一项报告称，大腿和臀部脂肪较多的人可能更长寿，因为脂肪能锁住有害的脂肪颗粒，并可有效分泌出有益化合物。

很多研究表明，腹部脂肪多的人死于心脏病和其他疾病的可能性大于臀部脂肪多的人，但原因尚不清楚。

英国牛津大学的康斯坦第诺斯．马诺洛波洛斯说，这可能是几种不同机制共同作用的结果。

马诺洛波洛斯在发表于《国际肥胖期刊》的研究报告中写道：“下半身即臀部脂肪的保护性作用是惊人的。”

他说：“下半身脂肪的保护特性已在很多研究中得到验证。”

马诺洛波洛斯为撰写这份研究报告查阅了已发表的相关科学研究。他说，臀部和大腿的脂肪储存了多余的脂肪酸。

此外，“梨形”身材的人体内的一种叫做“炎性细胞因子”的化合物的含量似乎更低。这种信号性化学物质与身体对感染的反应有关，而且如果它们过于活跃，可能会导致心脏病和糖尿病。

马诺洛波洛斯说，大腿上的脂肪可能还会吸收饮食中的脂肪，在人们吃得过饱时使它们不对身体造成过大的负担。

胆固醇水平反映了高浓度脂蛋白和低浓度脂蛋白之间的一种复杂的平衡关系。高浓度脂蛋白是一种良性胆固醇，可清除血液中的有害脂肪；而低浓度脂蛋白是一种恶性胆固醇，会造成动脉硬化或堵塞。

马诺洛波洛斯说，大腿上的脂肪也更加稳定，一些研究表明腹部脂肪可通过节食或压力迅速化解，将潜在的有害化合物从脂肪中释放出来。

马诺洛波洛斯写道：“脂肪酸释放和存储的具体调节机制以及它们对脂肪酸短期和长期代谢的影响仍有待分析。”

另外，腿部脂肪的燃烧更易产生瘦素等激素，瘦素由脂肪分泌，能够影响食欲和新陈代谢，不过马诺洛波洛斯说人们对其认识还不够。

马诺洛波洛斯说，了解这些知识能够让我们研制出更好的治疗肥胖以及糖尿病和心脏病等相关疾病的药物。

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 贮藏处

metabolism: the chemical processes in living things that change food, etc. into energy and materials for growth 新陈代谢

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