零度可乐喝多了反而会增肥

“如果它听起来太美好，简直不像是真的，那很可能就不是真的。”人工增甜剂的例子就属于这种情况。

一份新的研究发现，没有证据显示人工增甜剂能帮助人们减肥。相反，这份报告分析了对低卡路里和无卡路里增甜剂的37份研究，得出的结论是这些糖类替代品会导致体重增加，食用者未来还可能会有健康问题。

这份报告发表于《加拿大医学协会期刊》，给在食品和饮料中采用人工增甜剂（而不是糖）对健康有益的想法泼了盆冷水。这是条重要的消息：自20世纪90年代以来，由于美国人对糖类越来越警惕，低卡路里的增甜剂在美国的使用量迅速攀升。

综述所分析的研究中，有7项是随机调查，30项是观察调查（也就是对研究对象的习惯和健康状况进行了一段时间的观察）。随机调查选择的对象总计1,000名，其中大部分都试图减肥，然而研究人员没有找到人工增甜剂导致体重减轻的证据。

观察调查涉及的对象总计约40.6万人。研究人员发现人工增甜剂与身体质量指数的小幅增加（以及罹患II型糖尿病的概率小幅增加）呈现相关。当然，值得指出的是，这些研究是观察调查，因此没有实验对照组，无从判定人工增甜剂是否确实导致了BMI的增加和糖尿病患病风险的增加。不过它对低卡路里的增甜剂有助于缓解普遍肥胖的想法提出了进一步的质疑。

尽管综述针对的是人工制造的糖类替代品（例如阿斯巴甜和糖精），但它也对“天然的”糖类替代品表示了怀疑。例如从植物中提取的甜菊糖，以及常常被宣称能神奇地产生甜味却不会对健康产生负面影响的赤藓糖醇。

对于人工增甜剂这样的替代品会给身体带来哪些长期影响，我们所知甚少，这多少会引发人们的担忧。研究人员认为，它们会影响肠道细菌，以及身体处理糖类的能力，尽管这些说法尚未得到证实。

人工增甜剂还会影响习惯的养成。许多利用糖类替代品的公司都宣称他们的垃圾食品是“健康”版的。其中最著名的品牌之一就是低卡路里冰淇淋公司Halo Top。该公司一品脱巧克力冰淇淋只有280卡路里，而一品脱哈根达斯巧克力冰淇淋的热量大约是1,040卡路里。之所以有这么大的差异，是因为Halo Top在配方中采用了甜菊糖和赤藓糖醇，以减少糖类的使用。

Halo的广告中透露的强烈意思是他们的产品对你的健康很好——实际上，实在是太好了，以至于他们甚至表示一口气吃掉一品脱冰淇淋没什么问题，甚至鼓励你这么做。（公司的网站写着：“拿好你的碗，你会想要吃掉这整整一品脱。”而其盖子上还写着：“吃到底再停下。”）Halo Top并对应要求对此做出评论。

营养学家担心这类信息无益于帮助减肥者，而是在鼓励他们培养不健康的饮食习惯，这最终会导致增肥。哥伦比亚大学人体营养学院的副主任莎伦·阿卡巴斯表示，Halo这样的产品一方面“可以被视作减轻危害的产品，另一方面，公司又因为‘健康Halo’的形象而受益——这里不是双关。人们忘记了这些产品很大意义上仍然是垃圾食品。它们混淆了垃圾食品与否的界限。”

纽约大学营养、食品研究和公共卫生领域的教授马里昂·奈斯德对此表示同意。她在给《财富》的邮件中表示：“更好的办法可能还是在食品中少加点糖。”

这份关于人工增甜剂的研究是一个很好（也许也是令人沮丧）的提醒：想减肥，几乎没有捷径可走。（财富中文网）

译者：严匡正

File this one under "if it sounds too good to be true, it probably is."

A new review found no evidence that artificial sweeteners actually help people lose weight. Instead the report, which analyzed 37 studies on low and no-calorie sweeteners, linked these sugar replacements to weight gain and future health problems.

Published in Canadian Medical Association Journal, the report puts a damper on the idea that switching to food and beverages sweetened with artificial sweeteners (rather than sugar) has any major health benefits. This is important news: Since the 1990s, the use of low-calorie sweeteners in the U.S. has skyrocketed as Americans have grown increasingly wary of sugar.

Of the reviewed studies, seven were randomized and 30 were observational (meaning participants’ habits and health were tracked over a set period of time). After studying the randomized trials, which consisted of a total of 1,000 people, most of whom were trying to lose weight, the researchers found no evidence that artificial sweeteners led to weight loss.

From the observational studies, which consisted of around 406,000 participants in total, the researchers found a link between artificial sweeteners and a small increase in BMI (plus a slight increase in the likelihood of developing Type 2 diabetes). It’s important to note, of course, that because these studies were observational, meaning there was no control group, it’s impossible to determine whether artificial sweeteners actually caused the uptick in BMI or diabetes risk. But it further questions the idea that low-calorie sweeteners are the answer to the obesity epidemic.

While the review focused on artificial sugar substitutes (such as aspartame and saccharin), it casts doubt on “natural” sugar replacements like stevia—which is derived from a plant—and the sugar alcohol erythritol, which are often advertised as magical replacements able to recreate sugar's taste without recreating its detrimental consequences on health.

As with artificial sweeteners, some of this concern arises from how little we know about these replacements’ long-term effects on the body. Researchers have suggested they could interfere with gut bacteria and the body’s ability to process sugar, although these theories are unconfirmed.

It also has to do with habit building. A number of companies that use sugar replacements market themselves as “healthy” versions of junk food. One of the most prominent is the low-calorie ice cream brand Halo Top. A pint of its chocolate ice cream contains 280 calories, versus the roughly 1,040 in a pint of chocolate Haagen Daz. To achieve this discrepancy, Halo Top uses both stevia and erythritol to cut back on the amount of sugar in its recipe.

Halo’s advertising leans heavily on the idea that its products are good for you—so good for you, in fact, that it’s fine, encouraged even, to eat an entire pint in one sitting. (“Save the bowl, you’re going to want the whole pint,” its website reads, while Halo pint lids come emblazoned with the command to “stop when you get to the bottom.”) Halo Top did not respond to a request for comment.

Nutritionists worry that this type of messaging, instead of helping those trying to lose weight, encourages unhealthy eating habits that lead to weight gain. Products like Halo, on one hand “can be seen as a form of harm reduction,” says Sharon Akabas, the associate director of the Institute of Human Nutrition at Columbia University. “On the other hand they benefit from being a 'healthy halo' -- no pun intended. People forget they are still mostly a junk food. Products like these blur boundaries.”

Marion Nestle, a professor of nutrition, food studies, and public health at New York University, concurs. “A better approach might be smaller portions of the real stuff," she tells Fortune in an email.

The review on artificial sweetener serves as a good (if frustrating) reminder that when it comes to weight loss, there are few, if any, shortcuts.