“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. This decreased metabolic efficiency may ‘prime’ the body to store more fat,” said Dr Shanon Casperson, lead author of the study from USDA-Agricultural Research Service Grand Forks Human Nutrition Research Center, USA to Science Daily.
Fat oxidation is a process through which fat-molecules begin to breakdown. Researchers have found that sugary drinks decreased fat oxidation by 8% after a meal thus letting more fat accumulate in your body. A 15% protein meal if consumed with a sugary drink results in decrease of fat oxidation to 7.2 grams on average and this keeps on decreasing as the percentage of protein in the meal is increased. It also increases the amount of energy required for metabolising the meal.
“We were surprised by the impact that the sugar-sweetened drinks had on metabolism when they were paired with higher-protein meals. This combination also increased study subjects’ desire to eat savory and salty foods for four hours after eating,” added Casperson. The research involved 27 participants having a healthy weight and the average age of 23 years. They were given two meals consisting of 15% protein after an overnight fasting. They came in on another day under the same conditions and were again given two meals but the protein was increased to 30 per cent.
In the second meal with the extra proteins, carbs were decreased for balancing the meals and all the food items were kept same throughout the research. Now, the participants had a sugar-sweetened drink with a meal and a non-sugar sweetened drink with the other. The researchers now needed to determine the nutrients being used by the participants and the amount of calories they are burning through a calorimeter. This process took place on both study days.
“Our findings suggest that having a sugar-sweetened drink with a meal impacts both sides of the energy balance equation. On the intake side, the additional energy from the drink did not make people feel more sated. On the expenditure side, the additional calories were not expended and fat oxidation was reduced. The results provide further insight into the potential role of sugar-sweetened drinks — the largest single source of sugar in the American diet — in weight gain and obesity,” said Casperson shedding light on the results.