The Sweetener Paradox

It’s only human to wish you could indulge in that luscious chocolate brownie without consequences—by nature, we prefer sweet tastes. The problem is that sweets usually contain a high number of kilojoules and tend to send the blood sugar skyrocketing: not exactly a picture of healthy eating.

The invention of non-nutritive sweeteners (NNSs) at the end of the 19th century, however, seemed to turn the sweetness-kilojoule equation on its head. Chemical substances such as saccharin, cyclamate, aspartame and sucralose taste sweet but have very few kilojoules.

Thus, replacing dietary sugar with a low-kilojoule, high-intensity sweetener should enable a person to enjoy sweet-tasting treats while keeping energy intake under control. But can our taste buds and our waistlines really both win?

Maybe not

A growing number of scientific studies are showing, paradoxically, that the use of various NNSs may actually promote weight gain. Recent studies on rats, for example, showed that those consuming NNSs increased their food intake and gained more weight than those consuming kilojoule-rich glucose (sugar).

Human studies, too, are showing that low-kilojoule sweeteners may not be the diet savers they are purported to be. One survey of more than 78,000 women found that NNS users were more likely to gain weight than were non-users; a long-term study in Texas showed that people who consumed more artificially sweetened beverages were much more likely to be overweight or obese.

Sweet mystery

The exact mechanism by which low-kilojoule sweeteners lead to weight gain is still a scientific puzzle. One leading theory is that, by dissociating sweetness from kilojoules, NNSs confuse the body’s regulatory mechanisms. That is, when a person tastes something sweet that contains few kilojoules, the taste fails to evoke the normal psychobiological responses that serve to regulate energy balance and signal when to stop eating.

Another possible explanation for the association between NNSs and weight gain may be that artificial sweeteners change the intestinal environment and trigger inflammatory processes that are associated with metabolic disorders. While only a few animal studies have explored this hypothesis, it is plausible that a change in humans’ intestinal bacteria could promote fat storage and weight gain.

Finally, recently discovered sweet-taste receptors in the gut might explain the association of NNSs with weight gain. According to this theory, when certain gut receptors sense sugar, they trigger the release of hormones that stimulate insulin secretion and a feeling of satiety. Human studies have indicated that glucose, but not NNSs, may trigger these normal hormonal responses.

Whatever mechanism turns out to be responsible, one thing is already clear: the assumption that NNSs reliably promote weight loss needs to be seriously reconsidered.

The sweetener lowdown

Here’s the lowdown on the NNSs currently approved for use in Australia:

Natural is sweet

The next time you have a hankering for a sweet substance, try one of these natural alternatives.

Honey

A chemically complex food with more than 180 components, honey is a natural and highly versatile sweetener. Studies have shown that unpasteurised honey may be able to inhibit the effects of toxic substances present in the body. Honey is commonly drizzled over fruit, yoghurt or desserts and is used in baking and cooking.

Stevia

Stevia is a powdered extract that comes from a shrub called Stevia rebaudiana. Unlike other natural sweeteners, it is very low in kilojoules. Approved for use in Australia since 2008, it is an ingredient in tabletop sweeteners such as PureVia.

Coconut palm sugar

A natural sweetener from Southeast Asia, coconut palm sugar is low on the glycaemic index, which makes it a good choice for people who are watching their weight and their glucose levels. Coconut palm sugar cooks, dissolves and melts like regular sugar, but it has a rich flavour similar to brown sugar. It is a rich source of potassium, zinc and iron as well as vitamins B1 and C.

Agave nectar

Produced from seven-year-old agave plants grown in Mexico, agave nectar has a lower glycaemic load than regular sugar and a flavour somewhat sweeter than honey. With its thin, syrupy consistency, it can be drizzled over foods or added to drinks and sauces.

Maple syrup

Maple syrup is a sweet substance derived from the sap of maple trees; it has fewer kilojoules and a lower glycaemic load than honey, and is a dietary source of manganese and zinc. Its distinctive earthy, sweet taste pairs perfectly with pancakes and waffles, but it is also commonly used as a sweetener in desserts and baked goods.