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Do artificial sweeteners lead to weight gain? A lot of people rushed to judgment against artificial sweeteners based on preliminary evidence that they might increase appetite or sugar cravings, or even cause elevated blood sugar levels. But the ensuing research has failed to deliver a definitive indictment.

Although there seems to be a correlation between diet soda consumption and weight gain, it is hard to say whether this is a biochemical effect. It could just be that people prone to weight gain are more likely to choose sugar-free foods in an (apparently ineffective) attempt to stem the tide.

I've also always suspected a behavioral component. Maybe people unconsciously over-compensate for the calories they save with the diet soda. ("I'm having a diet soda so maybe I can afford to have dessert.")

Last summer, a large study found that artificially-sweetened foods appeared to be helpful for weight loss. But artificial sweeteners were just one of many tools that the successful dieters used to manage their calorie intake. What the study really shows is that those who employ the most weight management strategies are the most successful.  In other words, for those who are not fully committed to dietary restraint across the board, artificially-sweetened foods probably don't lead to weight loss.

Meanwhile, other researchers have been trying to pin down the biochemical aspects. For example, studies in rodents showed that sucralose (Splenda) speeds the uptake of glucose eaten at the same meal--leading to a sharper rise in blood sugar. That's not good.  At the same time, this rise in blood sugar also appeared to trigger release of a hormone that signals fullness.  That could be helpful.

Whether the upshot of all that ends up being positive or negative for weight loss turns out to be moot. The latest study indicates that sucralose doesn't seem to have the same effect on blood sugar uptake or appetite-regulating hormones in humans as it does in mice. 

Clearly, we don't have the final answer on how artificial sweeteners might support or sabotage weight loss. According to the research, artificially sweetened foods appear to be a helpful tool for some; less so for others. But I think the effects (both biochemical and psychological) vary greatly from individual to individual.

Ultimately, however, my bias towards less-processed foods makes me suspect that we'd really be better off without them.

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