Caffeine drinks may contribute to obesity

Energy drinks containing high levels of sugar and caffeine may be contributing to New Zealanders' expanding waistlines, new research suggests.

The project, headed by Auckland University of Technology Professor of Nutrition Elaine Rush, has found an energy drink containing sugar, added caffeine and guarana (which also contains caffeine) causes the body to convert sugar into fat more rapidly than lemonade.

"These results could have huge implications when you think about how much sugar and caffeine people consume these days, and the high rates of inactivity," Prof Rush said.

The project recruited 10 healthy women aged 18 to 22 from a range of ethnicities. The women fasted overnight and were randomly given either 250ml of an energy drink or lemonade on the first day and the alternative on the second day of testing.

Lemonade was chosen because, while both drinks contain the same amount of sugar and are carbonated, it doesn't contain caffeine.

"When the women drank either the energy drink or lemonade, the sugar was absorbed into their systems within a minute, giving them an immediate sugar rush," Prof Rush said.

She said she was surprised at how fast the sugar was absorbed.

"Sugar is a simple carbohydrate and evidence from this study shows that, coupled with a large amount of caffeine, the body rapidly turns it into stored fat."

The energy drink contains 28g sucrose and 81mg caffeine per 250ml can, similar to the amount of sugar in soft drinks and caffeine in a brewed cup of coffee.

Prof Rush said she was worried about the health effects on people who consume too many high-sugar, highly caffeinated products.

She said the study had limitations, with its small sample size and the fact the subjects were all young women, but its results were important as this area has not been explored before.

- NZPA