Forbes — Drinking a sugar-sweetened drink with a high-protein meal primes your body to store more fat, according to a new study.
Researchers found that sugary drinks decrease fat oxidation, the process that begins the breakdown of fat molecules. The more protein in the meal, the more fat oxidation decreases.
For example, a sugary drink with a 15% protein meal decreased fat oxidation by an average of 7.2 grams. With a 30% protein meal, the decrease jumped to 12.6 grams, and so forth.
“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,” according to Dr. Shanon Casperson, lead study author. “This decreased metabolic efficiency may ‘prime’ the body to store more fat.”
To put this in context, a decent-size hamburger may weigh around 130 grams, about 30 of which are protein. If you slam it down with a glass of sugar-sweetened soda, this study predicts that your fat metabolism will decrease somewhere in the neighborhood of 10 grams.
And that’s not all that happens, report the researchers. “This combination [of a sugar-sweetened drink with a high-protein meal] also increased study subjects’ desire to eat savory and salty foods for four hours after eating.”
So in addition to burning less fat, your body is also on the hunt for something salty, which is probably going to be found in a less-than-healthy snack.
A few caveats: this was a small study of 27 adults, average age 23, who were all in the healthy weight range. The general population is heavier on average, so it’s hard to know how these results would apply more broadly. Fat oxidation could be worse, or the difference might be less significant if someone’s metabolism is already slower than the average person in this study group.
In any case, the results throw a little more light on why the typical “American diet” often leads to obesity, metabolic syndrome and worse.
Quoting Dr. Casper: “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.”
The study was published in the journal BMC Nutrition.