Having a soda with your burger affects your metabolism, study says.
soda pairings burger and fries with soda
Credit: id-art / Getty Images

When you want to shed pounds, you shouldn't shy away from protein. Research has proven protein-packed foods—beef, chicken, yogurt, nuts, fish, and so many more—help the body burn fat. But a new study has a caveat to this facet of dieting: if you wash down your chicken breast or tuna sandwich with a sugary beverage, you could gain weight.

For the study, published in BMC Nutrition, researchers assigned meal plans to 27 young, healthy participants, which they ate while confined in isolated rooms that measured the levels of oxygen, carbon dioxide, temperature, and air pressure, in each space. With those measurements, the researchers could calculate how the participants' meals affected their metabolism and how well they broke down fat.

Meals of moderate and high protein were served alongside both sweetened and artificially sweetened beverages. The researchers soon found that when a sugary beverage was paired with a protein-packed meal, participants ability to burn fat dropped by eight percent compared to when they drank an artificially sweet drink Of course, the sugary beverage also added (unhelpful) calories to the meal too.

"We found that about a third of the additional calories provided by the sugar-sweetened drinks were not expended, fat metabolism was reduced, and it took less energy to metabolize the meals," Shanon Casperson, the paper's lead author and a researcher at the USDA-Agricultural Research Service Grand Forks Human Nutrition Research Center, broke down in a written statement. And, of course, "this decreased metabolic efficiency may 'prime' the body to store more fat," she added.

In other words, sugary drinks are bad news for fat-burning. Not only do they add calories that won't keep you full, but they prohibit foods that should help you burn fat from doing their jobs. So, the next time you want to wash down your burger with a Coke, think twice. Water will still get the job done.