一项意义重大的研究表明哪怕时身体稍微发福，患癌症的可能性就会增加，例如常见的乳腺癌、肠癌和胰腺癌。
目前最大的一次针对饮食和癌症之间关系的审查活动涉及到了7，000多项研究，得出的结论认为有充分的证据说明过量的身体脂肪至少会引发六种疾病。研究人员警告说人人都应该把体重保持在最低的健康范围内。
他们建议大家不吃加工过的肉类如火腿、熏肉、腊肠或其他经过烟熏腌制的肉类制品；少吃暗红色的生肉；适量饮酒；最后还建议不要用垃圾食品和甜质的饮料。
迈克-马莫教授领导着世界癌症研究基金所属的专家评审小组审查饮食致癌的有关证据。他曾说过自己非常惊讶于体重致癌的严重性。
十年前，该基金公布的一项报告只提到了一种癌症与肥胖的关系。而现在马莫教授认为已有证据证明至少由六种癌症（食道矮、胰腺癌、肠癌、乳腺癌、肾癌和子宫壁癌）与之有关，而且哪怕每增重一点点患该类疾病的危险性都会加大。
如今英国人的腰围继续增加，这项发现就显得异常耸人听闻。上个月，官方报道警告说到2050年60%的男士，50%的女士和25%的孩子将成为临床肥胖症患者。
健康的体重通常定义在体重指数在25以下。在计算体重指数时体重的单位是千克，身高在进行平方运算时单位是米。
迈克爵士说：“体重指数为25是正常情况，如果该数值再降一点就更好了。最健康的身体要在标准范围内把指数降到最低水平。“报告告诫大众要适量食用暗红色肉，建议用量为五百克，约合十八盎司。报告还强烈推荐大众不食用加工过的肉，其原因为吃了该类肉制品将加大结肠癌的患病率。
世界癌症研究基金的这份报告强调了参与锻炼的意义--即可直接作用于癌症，又有助于身体超重导致的肥胖。报告共提供了十条建议。除了其中的一条外，其余九条均与为避免其他常见死因（如心脏病）所采取的做法相一致。
唯一例外的便是饮酒问题。马莫教授认为已有证据表明饮酒会降低患心脏病的几率。他说要预防癌症，滴酒不能沾，但是为预防心脏病男士可以每天喝二两，女士每天喝一两。该评审小组认为应该让公众认可为把心脏病发生率降低到最低度而设定上述饮酒标准。
此报告是建立在针对二十世纪六十年代以来全球癌症研究基础之上的。最初的研究调查涉及到五十万例患者，后来减少到七千例。九个小组分析了调查的结果并呈报于由二十一位优秀科学家组成的评审小组予以审批。科学家们研究了人身体上的十七种癌症，涉及了很广的致癌因素范围，主要集中于促使该疾病高发率的饮食方面。
马莫教授说：“我们的建议是大家在健康允许的范围内要尽量地消瘦些，而且他们应该避免成年时期身体发福。这可能听起来挺难的，但是科学已经很明确告诉我们应该这样做。事实上，哪怕你的身体目前仍在健康的范围之内，只要体重升高了癌症的患病率就会提高。
Being even slightly overweight can increase the risk of a range of common cancers including breast, bowel and pancreatic cancer, a landmark study has found.
The largest review of links between diet and cancer, incorporating more than 7,000 studies, concludes that there is convincing evidence that excess body fat can cause at least six different types of the disease. The researchers give warning that everyone should be at the lower end of the healthy weight range.
Their recommendations include avoiding processed meats such as ham, bacon, salami or any other meat preserved by smoking, curing or salting； only consuming small amounts of red meat； moderate consumption of alcohol； and avoiding junk food and sweet drinks.
Professor Sir Michael Marmot, who chaired the expert panel assembled by the World Cancer Research Fund (WCRF) to review evidence on the dietary causes of cancer, said he had been shocked to find that weight was so important.
A report by the fund published ten years ago linked only one cancer to being overweight. Professor Marmot said the evidence now showed that at least six – cancers of the oesophagus, pancreas, bowel, breast postmenopause, kidney and endometrium (womb lining) – were linked and that the risks were increased by even quite modest weight gains.
The finding is particularly alarming, given the expanding girth of the British population. An official report last month gave warning that by 2050, 60 per cent of men, 50 per cent of women and a quarter of all children could be clinically obese.
A healthy weight is defined as having a body mass index (BMI) below 25； BMI is calculated by dividing an individual’s body weight in kilograms by the square of the height in metres.
Sir Michael said: “A BMI of 25 is fine, but it would be a bit finer if it was lower. The healthiest thing is to be as low as possible within the normal range.” The report suggests moderation in the consumption of red meat, suggesting a limit of 500g (18oz) per person per week. A total avoidance of processed meats is recommended because of convincing evidence that eating meat increases the risk of colon cancer.
The WCRF report emphasises the benefits of exercise, for its direct effects on some cancers, and because it helps to prevent becoming overweight or obese. It made ten recommendations which do not, save in one case, conflict with advice given for the avoidance of other common causes of death, such as heart disease.
The exception is alcohol, which Professor Marmot said had been shown to cut the risk of heart disease. For cancer prevention the optimum level is zero, but for heart disease it is two units a day for men and one for women, he said. The panel agreed that the levels set for minimum heart risk should be accepted.
The report is based on an analysis of cancer studies from around the world dating back to the 1960s. The initial trawl produced half a million studies, which was pared down to the best 7,000. The results were analysed by nine teams and then presented to a panel of twenty-one leading scientists for their recommendations. They looked at cancers at 17 different sites in the body and at a wide range of factors, mostly dietary, that can affect risk of developing the disease.
Professor Marmot said: “We are recommending that people aim to be as lean as possible within the healthy range, and that they avoid weight gain throughout adulthood. This might sound difficult but this is what the science is telling us more clearly than ever. The fact is that putting on weight can increase your cancer risk, even if you are within the healthy range.”