Nutrition Notes
Week of May 5, 2008
Contact: Sarah Wally, (202) 328-7744

Do Sweeteners Help or Hurt Weight Control?

Karen Collins, MS, RD, CDN
American Institute for Cancer Research

Grabbing a diet soda may seem like a smart choice for the calorie-conscious consumer. But a new study suggests that products containing artificial sweeteners have the potential to actually promote weight gain.

A recent Purdue University study suggests that artificial sweeteners (like the kinds found in diet sodas) might lead to biological or behavioral changes that make weight control more difficult, instead of easier. Putting this study within the context of overall research, however, we have little reason to believe that calorie-free sweeteners cause weight gain. How much they actually help weight loss may vary depending on how people use them.

Also important to note, the aforementioned study did not involve people; it was a laboratory study involving 17 rats. In the five-week long experiment, rats given yogurt sweetened with zero-calorie saccharin consumed more total calories (and gained more body fat) compared to rats that ate sugar-sweetened yogurt.

The psychologists who performed the study theorize that when our body tastes sweetness it prepares itself for a calorie load. If sweetness comes without calories – as is the case with artificial sweeteners – we keep on eating or reduce our calorie-burning metabolic activity.

For now, however, these theories are little more than speculation. And many researchers are quick to point out that a small, brief study involving rats cannot be used to form conclusions about humans.

True, there has been other research to support the hypothesis that artificial sweeteners thwart weight control efforts. But these findings are the result of observational studies that show that artificial sweetener use is more common in overweight than normal weight people. These types of studies can show us associations between people and behaviors, but they cannot prove that sweetener use causes overweight. In fact, it is highly likely that people who are overweight or are gaining weight might be more likely to choose diet soda and other foods with artificial sweeteners in an effort to control their weight.

Other studies refute the concerns about sweeteners. In a 10-week study of overweight men and women, subjects who were given a sugar-containing supplement increased their calorie consumption and gained body weight and fat, while those given a supplement with a low-calorie sweetener showed a small decrease in sugar consumption, body weight and body fat.

One of the few longer-term studies to examine this hypothesis involved obese women in a weight control program. Some women were asked to consume and some to avoid artificially sweetened foods and drinks during a 19-week weight loss program and throughout a 2.5-year follow-up period. Initial weight loss was similar, but the artificial sweetener group showed better weight maintenance during follow-up.

For now, studies provide little reason to fear that non-calorie sweeteners increase appetite or cause weight gain. Eating foods or beverages that contain artificial sweeteners can help your weight control efforts, but only if you use them wisely (for example, substituting them for higher-calorie foods to decrease overall calorie consumption). However, if using these sweeteners becomes an excuse to indulge in other high-calorie foods or to skip the physical activity that is so important to health and weight control, you will probably see no benefit.

Of course, “diet” drinks and foods are not essential. You could just as easily cut calories by swapping your soda for water, coffee or tea rather than a diet variety. Alternatively, you might put the focus on optimizing your nutrients and skip the zero-calorie snack foods altogether for a low-calorie piece of fruit with beneficial vitamins, minerals, fiber and phytochemicals.

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