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Chewing gum may only burn about three calories an hour, but the calorie expenditure is not just your little jaw muscles at work. For some reason, gum chewing revs up your heart rate, as much as an extra 12 beats per minute after chewing two sticks of gum. Here’s your heart rate and blood pressure five minutes before you start chewing; then chewing for five minutes; then you stop. That was them just sitting quietly. It also works while walking, increasing your heart rate by about three beats more per minute. And proving scientifically that people can indeed walk and chew gum at the same time.

But does this translate into weight loss?

Researchers at the University of Buffalo asked study participants to go for weeks chewing gum before every single eating occasion, or chew no gum at all. On the gum-chewing weeks, they didn’t just have to chew gum before each meal, but before each snack or even each drink that had any calories in it. This may have been too much for folks, so they actually ended up eating on fewer occasions, switching from four meals a day on average down closer to three. But they ended up eating more calories at each of those fewer meals; and so, had no overall significant change in calorie intake and, no surprise, had “no change” in weight.

University of Alabama researchers tried a different tack, randomizing people to chew gum after and between meals. After two months, compared to those randomized to avoid gum entirely, no improvements were noted in weight, BMI, or waist circumference. But what about those few studies that suggested gum chewing had an appetite-suppressing effect? In this study, people ate 68 calories fewer calories of pasta at lunch after 20 minutes of gum chewing. Yeah, but other studies showed differently.

Whenever there are conflicting findings, instead of just throwing your hands up, it can be useful to try to tease out any study differences that could potentially account for the disparate results. The obvious consideration is funding source. This was a publicly funded study, but that failed Alabama weight loss study was funded by a gum company. So, the outcomes are not necessarily predetermined.

Different types of gum using different sweeteners may have contributed to the diversity of findings. That one study showing gum chewing instead may actually increase appetite, for example, was done with aspartame-sweetened gum. People reported feeling hungrier after chewing the sweetened gum, not only compared to no gum, but compared to chewing the same gum with no added aspartame. True, not a single randomized controlled trial has ever shown a benefit to gum chewing, but they’ve all used gum containing artificial sweeteners.

There was a landmark study that showed that “sip size” matters. Have people drink at the same rate, but give them a sip every two seconds or a quadruple-sized gulp every eight seconds, and the smaller sip group won out, satiating after about one-and-a-half cups, compared to two cups when taking larger swigs. This is thought to be because of increased “oro-sensory exposure”—your brain is picking up the more frequent pulses of flavor and calories. But repeat the experiment with an artificially-sweetened diet drink, and the effect appears to be blunted. So, maybe a different type of gum would have a different effect? The positive pasta study was performed using gum mainly sweetened with sorbitol, a sweet compound found naturally in foods like prunes—but, like prunes, can have a laxative effect.

Case reports like this: “An air stewardess with puzzling diarrhoea” unveil what can happen when you eat 60 sticks of sorbitol-sweetened sugar-free gum a day. Another was entitled: “Severe weight loss caused by chewing gum,” but not in a good way. A 21-year-old woman ended up malnourished after suffering up to a dozen bouts of diarrhea a day for eight months due to the 30 grams of sorbitol she was getting chewing sugar-free gum and candies every day. Most people suffer gas and bloating at 10 grams of sorbitol a day, which is about eight sticks of sorbitol-sweetened gum, and at 20 grams, most get cramps and diarrhea. So, you want to be careful how much you eat.

The bottom line is that we have no good science showing gum-chewing results in weight loss. Could that be because the studies used artificial sweeteners that “may have counteracted” any benefits? Could be, but “the most obvious” explanation for the results to date “is that chewing gum simply is not an efficacious weight-loss strategy”— and that’s coming from researchers funded by the gum company itself.

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