How well do you remember the dinners you enjoyed with your friends, the ones where you left feeling as if you had eaten more than you could manage? Or in the opposite direction, the meals where you didn’t order a pudding, because nobody else did?

　　你可曾记得你和朋友一起享用晚餐时每次都吃得很撑?或恰恰相反，你和别人一起用餐时没有点布丁，仅仅是因为别人也没有点?

　　Perhaps you can blame social cues for eating too much or too little. Several decades of research shows that we eat more in company, and we follow what and how others eat.

　　或许，你可能把吃得太撑或没有吃饱怪罪于餐伴。几十年的研究表明，与朋友一起吃饭会让人胃口大开，而且我们用餐时会容易随大流。

　　But how exactly do our companions affect what we eat, and can we tap into these social influences to cut down on fats and sugar, and even lose weight?

　　不过，我们的用餐同伴究竟是如何影响着我们的饮食?我们又能否利用这些餐桌社交影响来减少脂肪和糖的摄入，甚至达到减肥的目的?

　　A series of diary studies by health psychologist John de Castro in the 1980s alerted us to social influences in eating. By 1994, de Castro collected diaries of over 500 people recording their meals and the social context of how they ate them – in company, or alone.

　　健康心理学家德卡斯特罗(John de Castro)在20世纪80年代进行的一系列日记研究告诉我们，要警惕社交对饮食的影响。截至1994年，德卡斯特罗收集了500多人的日记，记录他们的膳食以及他们在何种环境下用餐——同他人聚餐或是独自用餐。

　　To his surprise, people ate more in groups than when they were by themselves. Experiments by other scientists also found that people ate 40% more ice-cream and 10% more macaroni and beef in company than when alone. De Castro named the phenomenon ‘social facilitation’ and described it as the “single most important and all-pervasive influence on eating yet identified”.

　　让他感到惊讶的是，人们在聚餐时比独自用餐时吃得多。其他科学家的实验也发现，相较于独自用餐，人们在聚餐时多吃了40%的冰淇淋，及10%的通心粉和牛肉。德卡斯特罗将这一现象称为"社交助长作用"，并将其形容为"对饮食一项最重要和最普遍的影响，但作用尚待确定"。

　　What expands our palate when we eat with someone else? Hunger, mood, or distracting social interactions were all discounted by de Castro and other scientists. Studies reveal that we extend our meal times when we eat in a group, and we eat more in those extra minutes.

　　是什么让我们在和他人一起用餐时会胃口大开?在德卡斯特罗和其他一些科学家看来，饥饿、情绪或分散注意力的交谈都不是主要原因。研究表明，我们在多人聚餐时会延长用餐时间，于是给我们更多时间吃更多东西。

　　Careful observation in a range of eateries showed that bigger groups do enjoy longer meals. And when meal time is fixed, larger parties no longer eat more than smaller ones. In a 2006 experiment, scientists gathered 132 people and gave them either 12 or 36 minutes to eat cookies and pizza. The participants ate alone, in pairs or in groups of four. Within each specific meal time, participants ate similar amounts regardless of their party size. This lab experiment provided one of the strongest evidence that longer meal time is key to larger meal sizes in social eating.

　　仔细观察一批餐馆发现，聚餐人数越多用餐时间也就越长。与此同时，如果限制用餐时间，人数多的聚餐并不会比人数少的聚餐吃得多。2006年，科学家们召集了132个人进行实验，让这132个人在12分钟或36分钟内吃饼干和披萨，他们或独自、或两人一组、或四人一组用餐。在每个固定的用餐时间内，不论人数多少，吃的东西数量都差不多。这项实验为社交聚餐吃得多少取决于用餐时间长短提供了一个最强有力的证明。

　　It seems very plausible that when we dine with our friends, we might linger, and therefore reach for yet another slice of cheesecake.

　　和朋友们一起用餐时，我们很可能会磨蹭拖延时间，这样就能多吃一块芝士蛋糕。

　　When we anticipate a group meal, we even order more food individually. This was revealed from observations in an Italian restaurant: the larger a dining party, the more pastas and desserts each diner ordered. Social meals appear to make us hungrier, and it appears that we decide that we will indulge even before we order. Such observations led C Peter Herman, a food scientist, to propose his ‘feast hypothesis’: indulgence is part and parcel of social meals, and that we socialise partially so that we can all eat more without the guilt of overindulgence.

　　当我们预知是和几个朋友一起吃饭时，我们甚至也会给自己多点食物。我们在一家意大利餐厅观察发现：聚餐人数越多，点的意大利面和甜点也越多。社交聚餐似乎让我们感到肚子更饿，而且我们似乎还没点餐就决定要放纵一把。食品科学家赫尔曼(C Peter Herman)基于这一现象提出了"盛宴假设"的理论：放纵自己是社交聚餐的一部分，吃饭也是为了社交，这样就算吃得更多我们心里也不会有过度放纵的负罪感。

　　Furthermore, the joys of eating together could be felt even if our companion is not real. In a Japanese study, individuals were asked to eat popcorn alone either in front a mirror or an image of a wall. Those who ate before a mirror enjoyed the popcorn more. Have you ever noticed how many restaurants have prominent mirrors?

　　而且，我们即使不是跟真的同伴一起吃饭，也能感受到同人一起吃饭的乐趣。日本一项研究发现，参与研究的人被安排独自对着镜子或对着墙吃爆米花。那些对着镜子的人吃的爆米花较多。说到这里，你可曾注意到有多少餐厅在室內安装了引人注目的镜子?

　　But sometimes we do eat less in a company. Our drive to indulge can be tamed by the need to behave. We could manage our impression by eating according to social norms; or we might observe how others are eating and follow their lead, a behaviour called social modelling.

　　但有时候我们在与同伴聚餐时反而吃得较少，因为这时放纵的欲望会受到我们想要良好表现的压制。我们想要通过符合社会规范的饮食来管好自己的形象;或许我们可能会观察别人是如何吃东西然后仿效。这种行为称为社交示范。

　　There are plenty of examples. Studies showed that obese children ate less in groups than when they ate alone. Overweight youths ate more chips and cookies when accompanied by an overweight youth but not when they ate with someone of normal weight. In university cafés, women ate fewer calories with men at their table, but ate more in women-only groups. And across the US, diners ordered more desserts when served by heavier waiters.

　　这种例子有很多。有研究显示，肥胖儿童与人聚餐时比独自用餐时吃得较少。超重的青少年如果和也是超重的同伴在一起会吃更多的薯片和饼干，但是当他们与正常体重的同伴一起时就不会大吃特吃。在大学的咖啡馆里，女生和男生一起吃饭时摄入的热量較少，但是和女生同伴们在一起时就吃得较多。在美国各地餐厅，如果服务员体重过胖，食客们就会点更多的甜点。