The root of weight loss is eating less calories than you burn in a day, choosing the right foods, and exercising to stay healthy.

That said, those aren’t the only steps you can take to optimize your weight-loss regimen. According to new research, the timing of your meals also determines the way those calories are used by the body, and eating breakfast may work in your favor if you’re trying to target fat. It all comes down to the body’s circadian rhythm, which has to do with a lot more than just when you get sleepy.

Circadian rhythms are any “physical, mental, or behavioral changes that follow a daily cycle,” according to the National Institute of General Medical Sciences. In this particular study, researchers wanted to see how a person’s metabolism processes food at different points in the day and night.

They monitored the metabolisms of their subjects in whole-room respiratory chambers in two separate 56-hour sessions. In both sessions, the participants were given three meals a day, with lunch and dinner served at 12:30 p.m. and 5:54 p.m., respectively. In one of the sessions, they were given breakfast at 8:00 a.m., while the other provided them with a nutritionally equivalent meal at 10:00 p.m. instead. The overnight fast was the same for both sessions.

The researchers were surprised to find that although the total daily energy spent and nutrition was the same in both sessions, switching from breakfast to a late-night snack changed the way the body used carbohydrates and fat for fuel. When subjects ate right before going to bed, they burned less fat in a 24-hour period than when they ate breakfast and skipped the nighttime snack.

So is breakfast the most important meal of the day? We can’t say for sure, but the results of this study suggest that you should opt for breakfast instead of getting your calories in right before bed.