Why diet drinks may make you eat more

TheStar.com - sciencetech

Low-cal means you may head right back to the fridge

September 02, 2007
Leslie Scrivener

Which is better for you — Coke or Diet Coke?

Neither offers any nutrients, dietitians say, so which you drink becomes a matter of personal taste. "There's no such thing as better," says Stephanie De Maio, a registered dietitian at St. Michael's Hospital. Either one should be drunk in moderation, that is, infrequently, she says.

Some people like sweet taste or regular coke, which has 160 calories, and some people like the taste of Diet Coke, which has none.

We tend to associate diet drinks with weight loss or maintenance. But studies have shown that our bodies tend to compensate for calorie-reduced food or drink and demand more, which leads to overeating. As in: since I'm having a Diet Coke, I can also have a platter of French fries.

The most recent study, published last month in the academic journal Obesity, by David Pierce at the University of Alberta, found that young rats tended to overeat after they had been fed low-cal diets. In 2005, an eight-year study at the University of Texas showed that for each can of diet soda consumed a day, the risk of being overweight went up 41 per cent. In contrast, those who drank a can of regular sweetened soda every day, the risk went up 30 per cent.

Some diet soda drinkers may be concerned about the artificial sweetener, aspartame, which is the most studied food additive in history. Aspartame, made from amino acids, is 200 times sweeter than sugar. You don't need very much of it to sweeten a drink. Health Canada guidelines say we can safely consume 40 milligrams of aspartame per kilogram of weight, which means a 68-kilogram person would have to drink about 20 cans a day to get into the aspartame danger zone.

But not everyone can tolerate aspartame. "It's a definite no-no for any one with Phenylketonuria, or PKU," says Rena Mendelson, professor of nutrition at Ryerson University. Babies born in Ontario have been tested for decades for the genetic disorder, which prevents people from metabolizing phenylalanine, one of the amino acids in aspartame.

Coca Cola's latest pitch is to promote their products as "hydrating" drinks. New to the market is Diet Coke Plus with vitamins and minerals. It's on the shelves in the U.S. but hasn't been approved for sale in Canada.

Health Canada has strict regulations on food fortification. It allows for the replacement of nutrients lost in food processing – Vitamin D, for example, is added to milk when it's lost in pasteurization. But Food and Drug regulations do not not allow vitamins and minerals to be added if they were not present in the food in the first place.

The vitamins and minerals added in Diet Coke Plus (niacin, vitamins B6 and B12 and zinc and magnesium) are already found in most foods we eat daily such as bread, dairy products and meat.