You know the feeling; you head out for a pub lunch at work, or a big dinner on the weekend - and then end up curled up on the couch or staring blankly at your computer screen as your food coma kicks in.
But while the feeling is often blamed on carbs, a new study conducted in the US suggests that it is protein and salty foods that cause sleepiness after eating a big meal, rather than carbohydrates.
Researchers from Bowling Green State University looked into the links between eating and sleep, using fruit flies as subjects.
Though the research is only the first step into exploring the broader idea, the study suggests that the human body may need to work harder to digest foods high in protein and salt - which brings on a tired feeling.
“Clearly, protein is a very expensive commodity,” neuroscientist Dr Robert Huber, one of the research team, said, talking about plans to do further research to find out why foods high in salt and protein could cause sleepiness. “If sleep increases your ability to resorb it, that would be a possible reason. And the same thing with salt.” Carbohydrates, on the other hand, are much easier to come by in nature, he said, so might not call for such dedicated digestion.
Angus Stewart is a Senior Lecturer in Nutrition and Dietetics at Edith Cowan University, and he says that the study is incredibly valuable.
“It's very interesting that we may have evolved different mechanisms to make us sleepy after ingesting to give our bodies a better opportunity to digest,” he tells SBS Food.
“If you think about it, it’s quite similar to animals - they cannot digest food satisfactorily if they are being pursued or at risk, they need that quiet time.”
Stewart says it’s also important to remember that there are many variables involved and each person is different.
“You can also get a bit sleepy if you haven't had a large amount of protein for a while and eat a high protein meal, or if you've been eating very frugally and then go out for dinner and have a blast,” he says.
So, what’s the best approach if you do start to nod off after a salt or protein-filled meal?
“While it's sorely tempting to go and veg out on the couch, a little bit of movement does no harm,” advises Stewart.
He suggests waiting half an hour for your food to settle a bit, and then going for a walk to boost your activity level and stave off that food coma feeling.