We've all pretty much accepted the notion that if we burn as many calories as we consume, our weight will remain stable.

Add some exercise to the mix and your body will burn more than it takes in and you'll lose weight. Add an ice cream cone a day to your diet without increasing your activity and you're well on your way to obesity.

Some weight-loss programs preach the virtue of not eating anything after eight in the evening. However, there's a fair bit of research that suggests a calorie is a calorie to your body: it doesn't distinguish between daytime or nighttime calories.

Well, it might not be that simple.

If you've ever put your body through the wringer of working shifts, you'll know that it wreaks havoc with mealtime. It's tough to sit down to dinner when you should be eating breakfast or having lunch when everyone else you know is having breakfast. Then you hit your days off and you try to get on the same clock as your family. It's a recipe for a messed up gastro-intestinal system.

It'll hit you in one of two ways: you're either eating extra meals or your body gets so ticked with you, that your appetite shuts down.

Several studies have suggested links between working weird shifts and putting on extra weight – even when appetite is decreased.

The body just wasn't meant to be chowing down at three in the morning – at least not every day.

Now, new research suggests our circadian rhythm could be linked to weight gain. Our biological clocks were set around the time what became humans emerged from the primordial ooze. Unlike a lot of creatures, we're not naturally nocturnal. We did our food gathering during the day and hid from our predators at night.

Researchers at Northwestern University suggest that eating at irregular times – when your body wants to sleep – could influence weight gain.

The researchers put two groups of mice on a high-fat diet. They found that the group of mice that were fed during normal sleeping hours put on significantly more weight than mice on the same diet that ate during naturally wakeful hours.

"One of our research interests is shift workers, who tend to be overweight," said lead author Deanna M. Arble. "Their schedules force them to eat at times that conflict with their natural body rhythms. This was one piece of evidence that got us thinking – eating at the wrong time of day might be contributing to weight gain. So we started our investigation with this experiment."

The researchers plan to take their experiments further, to help determine how our body's natural rhythms and weight gain are linked.

Something to think about next time you find yourself reaching for a phone and a delivery menu at three in the morning.