For regular soft-drink drinkers, the risk of becoming overweight or obese was:
• 26 percent for up to 1/2 can each day
• 30.4 percent for 1/2 to one can each day
• 32.8 percent for 1 to 2 cans each day
• 47.2 percent for more than 2 cans each day.
For diet soft-drink drinkers, the risk of becoming overweight or obese was:
• 36.5 percent for up to 1/2 can each day
• 37.5 percent for 1/2 to one can each day
• 54.5 percent for 1 to 2 cans each day
• 57.1 percent for more than 2 cans each day.
For each can of diet soft drink consumed each day, a person's risk of obesity went up 41 percent.
The Mad Hatter Theory
"Take some more tea," the March Hare said to Alice, very earnestly.
"I've had nothing yet," Alice replied in an offended tone, "so I can't take more."
"You mean you can't take less," said the Hatter: "It's very easy to take more than nothing."
Lewis Carroll, Alice's Adventures in Wonderland
There is actually a way that diet drinks could contribute to weight gain, Fowler suggests.
She remembers being struck by the scene in Alice's Adventures in Wonderland in which Alice is offended because she is offered tea but is given none — even though she hadn't asked for tea in the first place. So she helps herself to tea and bread and butter.
That may be just what happens when we offer our bodies the sweet taste of diet drinks, but give them no calories. Fowler points to a recent study in which feeding artificial sweeteners to rat pups made them crave more calories than animals fed real sugar.
"If you offer your body something that tastes like a lot of calories, but it isn't there, your body is alerted to the possibility that there is something there and it will search for the calories promised but not delivered," Fowler says.
Perhaps, Bonci says, our bodies are smarter than we think.
"People think they can just fool the body. But maybe the body isn't fooled," she says. "If you are not giving your body those calories you promised it, maybe your body will retaliate by wanting more calories. Some soft drink studies do suggest that diet drinks stimulate appetite."