Artificial Sweetners and weight loss

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There was a recent article on Stevia in the New York Times. There seemed to be some question as to its safety, though it has been in use for some decades in North America, and even longer in Japan.

Stevia is a sugar substitute, with a claim of zero calories, similar to NutraSweet, Cyclamate, Sucralose, and Saccharine. Saccharine is not for sale in Canada, but the others are.

The Times article tried to raise questions of food safety with Stevia, but frankly, these are generally pretty safe. The trouble with raising food safety questions is that unless there is a focused issue for which there is widespread proof of its lack of safety, raising food safety issues willy-nilly just maintains paranoia.

The real issue we should all be concerned with is that, given the cost of these sweetners, are they really effective in helping us mange our weight? They might be good for helping the body to regulate insulin, since you are not consuming as much sugar (sucrose), but is that all?

The evidence of the negative health effects of added sugar in foods and those in processed foods is uncontroversial, according to an article from Consumer Reports from last year. This includes, of course, soft drinks, other junk foods, and any sugar that you would add to food in high quantity.

Eating for calories

In January of 2019, Doctors Dana Small and Alexandra DiFeliceantonio of Yale University School of Medicine’s Department of Psychiatry, published a short review in the journal Science, which began by giving a history of research on this topic. Early research into rats using diets equal to their spent energy (called an isocaloric diet) which varied in volume, indicated that rats’ preferred caloric intake is fairly constant across several days and trials. It indicates that “rats eat for calories”.

How do rats know about a certain level of calories? It was theorized that there must be a signal sent to the brain communicating the energetic value of the food. If that signal indicated a low value (high volume, same calories except diluted by something else), the rat would eat more. If the signal indicated a high value (low volume, same calories), it would eat less.

This has been replicated and then verified in human subjects. We can even form associations between flavours and calories. One of the most irresistible flavours to humans is the taste of sweetness, indicating the presence of sugar. If animal researchers introduced a blocker (namely 2-deoxyglucose) to prevent sugar metabolism, they found that it inhibited the animals’ ability to form food preferences. There appeared to be broader effects than just food preference inhibition, since dopamine levels appeared in lower than normal concentrations outside of the nerve cells. When glucose was put back in the diet, normal levels of dopamine returned. So hard-wired is this tendency to prefer sweetness in animals (of which we are one species) that it is referred to as an “un-conditioned stimulus” — it does not require conditioning to eat foods that are a bit sweet, we just do without hesitation, thinking it must be good to eat. These signals run independently of our conscious perceptions about the food.

The Mindless Margin

So, if humans eat for calories as well, it means that artificial sweetners can’t be relied on by themselves to help us cut back our caloric intake. A diet must account for the fact that we will have the urge to make up the calories in some other way. It comes down to self-control, but a true win over the battle of the bulge will depend on what one Cornell food scientist once called the “mindless margin” — or just enough self control over your food intake that your body doesn’t miss the lost calories, but your body still benefits by losing the weight, albeit more slowly than planned.