Sugar and Protein Don’t Get Along

Having a sugar-sweetened drink with a high-protein meal may negatively affect energy balance, alter food preferences and cause the body to store more fat.

Source: Bev Childress

The beverage industry spends $3.2 billion marketing sodas and other sugary drinks every year. Is it any surprise that you’ll find these drinks in just about every home in the country? With more than 240 calories and 15-18 teaspoons of sugar in each 20-ounce soda, it’s truly no surprise that we’re facing an ever-worsening obesity epidemic.

For those who are trying to eat healthily, soda and sweetened beverages are one of the first things to be cut from the menu. However, it’s sometimes nice to have a little something sweet with our meals. Just a few sips of soda can’t hurt that much, right?

According to a new study from the USDA-Agricultural Research Service Grand Forks, Human Nutrition Research Center has a clear answer: it definitely can.

Sugar-sweetened drinks tend to reduce fat oxidation after your meals by an average of 8% per meal. This means your body has a harder time breaking down fat molecules (both stored and dietary) when you eat. Ultimately, this leads to an increase in stored fat and a decrease in expended energy.

But when you pair sugar with a high protein meal, that’s when things get bad. Just a 15% protein meal can lead to a significant decrease in fat oxidation (7.2 grams). If it’s a high-protein meal (up to 30%), fat oxidation decreases even further, to 12.6 grams. And the effects don’t stop there.

Not only does a sugar drink/combo decrease fat oxidation, but it can take a negative toll on your metabolism. The amount of energy expended to burn the soda doesn’t make up for the number of calories consumed, especially not the high-glycemic calories of sugar. The combination can also increase your desire for salty and savory foods for up to 4 hours post-consumption, which can trigger those cravings that cause you to snack at the wrong times and on the wrong foods.

Dr. Casperson, lead author of the study from USDA-Agricultural Research Service Grand Forks Human Nutrition Research Center, USA  said: “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.”

Dietary changes were measured only for a short time and caution must be used when extrapolating the study data to dietary changes over longer periods of time. As this study was in healthy-weight adults only, the authors also caution that overweight individuals may respond differently to dietary changes.


1. Shanon L. Casperson, Clint Hall, James N. Roemmich. “Postprandial energy metabolism and substrate oxidation in response to the inclusion of a sugar- or non-nutritive sweetened beverage with meals differing in protein content.” BMC Nutrition, 2017; 3 (1).