It’s a question you'd expect waitstaff to ask you when you order a juicy steak meal or protein-laden chicken burger on a low-carb bun: ‘would you like a drink with that?’
One healthy way to answer is ‘yes’, before proceeding to order a glass of water or detox juice. But is it so bad to order a little, bubbly soft drink on the side if you’re sticking to a healthy, protein-rich meal?
According to a study, published in the Springer Nature journal BMC Nutrition, adding sugary soft drinks to your high-protein dishes order could be a diet-destroying move, even if your main meals are macronutrient-sound.
The USA-based research, conducted by the United States Department of Agriculture’s Agricultural Research Service, suggests the risk lies is in the combination of the sugar-sweetened soft drink and the high protein meal. Together, they may reduce your body’s ability to break down your meal, alter your food preferences and cause your body to store more fat.
In the 2017 study, scientists analysed the metabolic rates and appetites of 27 healthy adults aged between 18 and 28 (13 male, 14 female), who made two 24-hour research visits.
Together, they may reduce your body’s ability to break you’re your meal, alter your food preferences and cause your body to store more fat.
During visit one, each participant ate meals made up of 15 per cent protein (breakfast and lunch) after an overnight fast. On the second visit, the study subjects ate two meals consisting of 30 per cent protein, also after an overnight fast. The increase in protein was counterbalanced by a decrease in carbohydrates.
All of the meals tested featured the same foods, providing 17 grams of fat and 500 non-beverage calories.
Participants consumed a sugar-sweetened drink with one of the meals and a non-sugar sweetened drink with the other meal.
The researchers found that the inclusion of a sugar-sweetened drink with the high protein meal decreased the process of fat oxidation (which kick-starts the breakdown of fat molecules) after a meal by eight per cent.
The results showed that if a sugar-sweetened drink was consumed with a 30 per cent protein meal, fat oxidation decreased by 12.6 grams on average. If the sugary beverage was drunk alongside a 15 per cent protein meal, fat oxidation decreased by around seven grams.
Dr Shanon Casperson, lead author of the study, estimates that a third of the additional calories provided by the sugar-sweetened drinks were not expended during the study.
“Fat metabolism was reduced, and it took less energy to metabolise the meals,” Dr Casperson says in a press release. “This decreased metabolic efficiency may ‘prime’ the body to store more fat.”
The researchers also observed that by increasing the protein content of a meal, they could decrease the participants’ hunger level and increase their satiety (meal satisfaction).
Despite these results, the male participants tested seemed to be hungrier and less satisfied with their protein-rich meals than the female participants.
“Increasing dietary protein also decreased the desire to eat something savoury, salty and fatty and the males had a greater appetite for food with these taste profiles,” the study reads. “Interestingly, there was no effect of sex, dietary protein or beverage type on the desire to eat something sweet.”
How do Australian and US soft drinks compare?
Even though the study was conducted internationally, it still holds valuable lessons about soft drink and sugar consumption for us here in Australia.
According to the Australian Bureau of Statistics, Aussies are high consumers of soft drinks. The Australian Health Survey (2011-12) recorded that almost 40 per cent of males and 30 per cent of females aged over two years consumed a sugar-sweetened beverage on the day before the survey’s research interview.
Although it’s true that soft drinks in the USA are mostly sweetened with high fructose corn syrup while Australian soft drinks are usually sweetened with sugar cane-derived sucrose, research shows that four major soft drinks sold in Australia could have more sugar than their American varieties.
The average total glucose concentration of Australian soft drinks was one gram per millilitre higher than the same brands in the US.
A study conducted by the Baker Heart and Diabetes Institute, published in the MJA in 2017, shows that Coca-Cola, Fanta, Sprite and Pepsi sold in Australia has over 20 per cent more glucose on average than those in the USA. The average total glucose concentration of Australian soft drinks was one gram per millilitre higher than the same brands in the US.
So if you’re about to consume a soft drink with a main meal as a treat, be sure to know that it may set your diet back a little – even if the meal you’re enjoying seems healthy and is high in protein.
“Our findings suggest that having a sugar-sweetened drink with a meal impacts both sides of the energy balance equation,” Dr Casperson says. “On the intake side, the additional energy from the drink did not make people feel more sated [satisfied].
“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…”
More research is needed to determine the impact of sugary drinks with high protein meals on people who are overweight, who may respond differently to adults with a healthy weight.
