Last week I wrote about Truvia and PureVia, two new stevia-based sweeteners. Because they really are so new to the market, we don’t know a lot about them. They likely are safe. Then again, it’s hard to say what researchers will find years down the road. Whether you use nonnutritive sweeteners or not and which ones you use is really a matter of individual preference.
As far as nonnutritive sweeteners and weight are concerned, there are two cases against these products and one case in their favor. Most of us understand the basic premise behind weight loss: consume fewer calories than you expend to lose weight. It stands to reason, then, that eating or drinking foods and beverages that have few calories or even no calories can help in the quest to lose weight.
For the sake of comparison, a cup of black tea sweetened with a nonnutritive sweetener has 0 calories, while a cup of the same beverage sweetened with a teaspoon of sugar contains 16 calories. To take another example, a 12-ounce can of regular cola and has roughly 140 calories and 40 grams of carbohydrate, while the same size can of diet cola will come up empty in terms of calories and carbohydrate. Again, you don’t have to be a math whiz to figure out that the diet cola is probably a better choice for weight management (putting aside any feelings you may have about nonnutritive sweeteners, that is). But let’s have a look at what the science has to say…
Nonnutritive sweeteners can be a little deceiving. They may act like tricksters, fooling the body into thinking that it’s been deprived. Scientists at Purdue University tested this out: They fed one group of rats a yogurt sweetened with glucose. They fed another group of rats yogurt sweetened with saccharin. Guess what happened? The saccharin-yogurt-fed rats ate more, gained weight, and put on more fat than the rats that had eaten regular yogurt. And when the rats were fed Ensure, a liquid nutrition supplement, as a premeal snack, the saccharin-fed rats wanted more. Additionally, when mealtime came, these rats chowed down on more rat food.
Why did this happen? The scientists believe that nonnutritive sweeteners may somehow interfere with the body’s ability to “self-regulate,” meaning that artificially sweetened products affect the body’s ability to use sweetness as an indicator of how many calories a food or beverage contains, potentially leading to overeating of sugar-sweetened items. The Purdue researchers believe that nonnutritive sweeteners fool the taste buds: the taste buds sense sweetness and signal the brain to gear up for a sugar load. But those calories from sugar never come. As a result, things go a little haywire in terms of appetite regulation, leading the body to seek calories elsewhere. The end result is that you end up looking for something else to eat or drink later on. (Maybe that explains the people who order a Big Mac, large fries, and a Diet Coke?).
Even though only saccharin was studied in these experiments, the researchers believe the same “trickery” would occur with aspartame, acesulfame-K, and sucralose. We don’t know yet what would happen with stevia-based sweeteners, though.
There may be another reason why nonnutritive sweeteners haven’t scored so well in the weight-loss department. A professor of veterinary science at the University of Liverpool discovered a “sweet taste receptor” in intestinal cells that allows humans and animals to detect glucose in the gut. Nonnutritive sweeteners activate these receptors, just as glucose does, causing the intestines to absorb more glucose from food, and possibly hindering weight-loss efforts. (If this proves to be the case, it could lead to the development of drugs that block these glucose sensors in the gut, helping people to process less glucose — and fewer calories — from their food.)
Wait, not so fast — don’t toss out your sweetener packets just yet. Researchers in the US and New Zealand studied people who had lost weight and maintained a weight loss of at least 10% for 11.5 years. These people had to work harder at keeping their weight off compared to people who never had to lose weight. How did they do it? They consumed fewer calories from fat, ate more reduced-fat and reduced-sugar foods, drank more water, and had more artificially sweetened soft drinks and fewer sugar-sweetened soft drinks. The authors of the study, which was published in 2009 in the International Journal of Obesity, concluded that among the dietary strategies needed to maintain weight loss, the use of both artificial sweeteners and fat-modified foods should be examined further for both preventing and treating weight gain.
What’s your conclusion? Is the jury still out on nonnutritive sweeteners and weight management?