如果我問你，什麼構成「不良」飲食，你可能會回答那些導致肥胖和各種相關疾病的東西，「鹽、脂肪和糖。」這個邪惡三劍客已經困擾我們幾十年了。但這個答案並不充分。
我們對飲食和慢性病的關係還有很多不了解的地方，但是在這個問題上最有發言權的人說，相比經過高度加工的食品，真正的食物對健康更有利，不容易導致疾病。我們還可以進一步提煉這一要旨：我們的飲食主體，應該是經過極少加工的植物。（這話不只是我在說；美國國家醫學院[Institute of Medicine]和農業部[Department of Agriculture]都是認同的。）
然而我們正在面臨一個公共健康的緊急狀況，並且沒有給予足夠的重視。我們應該設立兩個新項目，這應該是國家的頭等大事，一個是研究項目，要準確地判定是什麼導致飲食相關的慢性病（其中最首要的問題是，「糖到底有多糟糕？」），另一個項目是要傳播一個簡單的訊息：吃真正的食物。
真正的食物能解決鹽/脂肪/糖的問題。是的，過多的鹽會導致或加劇高血壓，減少鈉的攝入對高血壓人群是有益的。但鹽只是導致高血壓的幾個風險因素之一，而且那些飲食種類多樣、很少食用加工食品的人，不需要操心鹽攝入的問題——典型的美式日常飲食中，80%以上的鈉來自加工食品。
「脂肪」是個含義豐富的詞，也是個錯綜複雜的話題，至今仍懸而未決。多數自然產生的脂肪可能都是必要的，但某些類脂肪——同樣，可能是那些高度加工的食品中使用的工業方法生產的脂肪——過多似乎是有害的。吃真正的食物，你的脂肪攝入大概就不會有問題。
「糖」已經成為（或者說應該成為）整整一類經加工、無營養、高熱量的甜味料的代稱，包括食糖、高果糖玉米糖漿以及一些號稱健康的代糖，比如龍舌蘭糖漿、糙米糖漿、濃縮果汁等等。
這些似乎都是有害的，因為它們是添加糖，和天然的糖不一樣，比如，在真正的水果中的糖是沒問題的。添加果糖可能比其他形式更糟，但是精製碳水化合物在體內可以迅速分解為糖，比如白麵包，可能對健康一樣沒好處。同樣：這些都是高度加工食品。
總而言之：糖不是敵人，或者說不是唯一的敵人。真正的敵人是高度加工食品，包括糖。
在美國這個全球最肥胖的國度里，最新數據顯示每年在肥胖問題上的花銷達到2000億美元（約合1.2萬億元人民幣）。（肥胖相關的支出無法計算，但每年超過1萬億美元應該不成問題。想財政收支平衡？吃真正的食物。）國家醫學院每年用在肥胖相關研究上的經費不到10億美元，而且沒有一個有說服力的大型研究（在這個問題上小型研究是沒用的）能提出解決肥胖潛在成因的辦法。如果解決方案就「鹽、脂肪、糖」這麼簡單，或者是那個越聽越荒唐的「卡路里進，卡路里出」(calories in, calories out)，我們現在應該已經有一些進展才對。
我們知道，吃真正的食物只是一個籠統的解決辦法，但我們的飲食問題，可能在相當程度上是源於高熱量甜味料和（或）高度加工碳水化合物的攝入，而這兩者在我們的飲食中幾乎是不可避免的，且攝入量在飛漲。在我們的食物產品中，有80%含有這些東西。
或者也有可能是和其他因素共同作用的，比如我們體內的細菌網絡在退化，而這個問題本身可能是過量使用抗生素或其他環境問題造成的。或者可能比這還要更複雜。
關鍵在於我們需要有確鑿的了解，因為只有攥着如山的鐵證，才有可能說服議員們去實施必要的政策。（在飲食的領域，尋找鐵證是很困難的，但是如果我們被這些困難嚇倒，那就是正中加工食品販子下懷了。）這方面只需要看看煙草的前車之鑒。
與此同時，如果我們在此期間一定要找一個目標，毫無疑問應該是高熱量甜味劑；它們跟體重增加、II型糖尿病等等問題是有明顯關聯的（而減少攝入也明顯和體重下降有關）。如何限制糖的攝入？首先可以徵收汽水稅，進行妥善標註也是有幫助的，此外還有限制向兒童推銷甜的「食物」——這很有可能是最重要的，因為要走出這片泥沼需要一代甚至兩代人的時間。
這些舉措都沒有理由再拖了。但是讓我們先從科學入手，找到儘可能充分的證據，得出堅實、可信、明智、公正的建議。同時，我們還要明確傳達一個要旨，那就是「吃真正的食物」。
翻譯：經雷
What Causes Weight Gain
By MARK BITTMAN June 13, 2014If I ask you what constitutes “bad” eating, the kind that leads to obesity and a variety of connected diseases, you’re likely to answer, “Salt, fat and sugar.” This trilogy of evil has been drilled into us for decades, yet that’s not an adequate answer.
We don’t know everything about the dietary links to chronic disease, but the best-qualified people argue that real food is more likely to promote health and less likely to cause disease than hyperprocessed food. And we can further refine that message: Minimally processed plants should dominate our diets. (This isn’t just me saying this; the Institute of Medicine and the Department of Agriculture agree.)And yet we’re in the middle of a public health emergency that isn’t being taken seriously enough. We should make it a national priority to create two new programs, a research program to determine precisely what causes diet-related chronic illnesses (on top of the list is “Just how bad is sugar?”), and a program that will get this single, simple message across: Eat Real Food.
Real food solves the salt/fat/sugar problem. Yes, excess salt may cause or exacerbate high blood pressure, and lowering sodium intake in people with high blood pressure helps. But salt is only one of several risk factors in developing high blood pressure, and those who eat a diverse diet and few processed foods — which supply
more than 80 percent of the sodium in typical American diets — need not worry about salt intake.
“Fat” is a loaded word and a complicated topic, and the jury is still out. Most naturally occurring fats are probably essential, but too much of some fats — and, again, it may be the industrially produced fats used in hyperprocessed foods — seems harmful. Eat real food and your fat intake will probably be fine.
“Sugar” has come to represent (or it should) the entire group of processed, nutritionally worthless caloric sweeteners, including table sugar, high fructose corn syrup and so-called healthy alternatives like agave syrup, brown rice syrup, reduced fruit juice and a dozen others.
All appear to be damaging because they’re added sugars, as opposed to naturally occurring ones, like those in actual fruit, which are not problematic. And although added fructose may be more harmful than the others, it could also be that those highly refined carbohydrates that our bodies rapidly break down to sugar — white bread, for example — are equally unhealthy. Again: These are hyperprocessed foods.
In sum: Sugar is not the enemy, or not the only enemy. The enemy is hyperprocessed food, including sugar.
In the United States —
the world’s most obese country — the most recent number for the annual cost of obesity is close to $200 billion. (Obesity-related costs are incalculable but could easily exceed $1 trillion annually. Wanna balance the budget? Eat real food.) The amount the National Institutes of Health expends for obesity-related research is
less than $1 billion annually, and there is no single large, convincing study (and no small study will do) that proposes to solve the underlying causes of obesity. If the solution were as simple as “salt, fat, sugar” or the increasingly absurd-sounding “calories in, calories out,” surely we’d have made some progress by now.
We know that eating real food is a general solution, but a large part of our dietary problems might stem from something as simple as the skyrocketing and almost unavoidable consumption of caloric sweeteners and/or hyperprocessed carbs, which are in
80 percent of our food products.
Or it could be those factors in tandem with others, like the degradation of our internal networks of bacteria, which in turn could be caused by the overuse of antibiotics or other environmental issues. Or it could be even more complex.
The point is we need to know for certain, because until we have an actual smoking gun, it’s difficult to persuade lawmakers to enact needed policies. (Smoking gun studies are difficult in the diet world, but throwing up our hands in the face of complexity serves the interests of processed-food pushers.) Look no further than the example of tobacco.
Meanwhile, if we had to pick one target in the interim, caloric sweeteners are unquestionably it; they’re well correlated with weight gain (and their reduction equally well correlated with weight loss), Type 2 diabetes and many
other problems. How to limit the intake of sugar? A soda tax is a start, proper labeling would be helpful, and — quite possibly most important, because it’s going to take us a generation or two to get out of this mess — restrictions on marketing sweet “food” to children.
There’s no reason to delay action on those kinds of moves. But let’s get the science straight so that firm, convincing, sound, evenhanded recommendations can be made based on the best possible evidence. And meanwhile, let’s also get the simple message straight: It’s “Eat Real Food.”
Fred R. Conrad/The New York Times馬克·比特曼
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