When it comes to eating in the evening, dieters are often concerned that meals past 8 p.m. could add to their waistlines, but new evidence suggests more alarming consequences: heart disease and diabetes.

Related: Low-Carb Diet? Your Taste Buds Are Literally Working Against You

Researchers from the National Autonomous University of Mexico found that eating late goes against our biological clocks, and looked into how our out-of-sync lifestyles impacts overall health. As they note in the paper, published today in Experimental Physiology, previous research has already shown that disturbing the circadian rhythms could cause metabolic irregularities. Circadian rhythms are the processes our bodies go through in 24 hours, like digestion, and are regulated in part by our biological clocks.

To study the effects of those midnight snacks, the team fed rats at the beginning of their rest period (in humans, this would be just when it gets dark, according to lead study author and neurobiologist Ruud Buijs) and also during their active phase. They found that rats had higher amounts of blood fat levels following a meal during their rest time. After removing a part of the animal’s brain that regulates the 24-hour cycle, the variance in fat was gone. As high fat levels found in the blood are linked to an increased risk of heart disease and diabetes, the team concluded that eating late increases one’s risk of these chronic conditions.

“​Probably the most serious crime against our own clock is to eat late at night,” Buijs told Newsweek.

He explained why eating lunch doesn’t cause the same spike in fat levels, and the reason is relatively simple: our bodies aren’t prepared for the onslaught of calories at night. Buijs said that because our biological clocks are synchronized by light and day, our bodies use these cues to prepare for active and sleep modes. So when you're stuffing your face with fries at bedtime, the body is confused and can't handle the nutrients. These stick around your body for longer periods of time and are taken in by fat tissue, Buijs explained. 

Outside of late night stops at the drive-thru, Buijs said that traveling to different time zones is the second most common offense that disturbs people’s biological clocks. But you can try to minimize the effects by immediately changing your schedule to reflect the local time.

“For myself, I usually try to adapt as quickly as possible to my new time schedule,” he said. However, if you’re only traveling for a few days, Buijs said it's best to act like you're in your home time zone. “Then you will be the least disturbed,” he said. Although, it might inhibit your sightseeing. 

While this study was performed in rats, psychologist Cassandra Gipson-Reichardt, an outside researcher who studies neurobiology and addiction at Arizona State University, told Newsweek the paper is an interesting addition to the progress already made exploring nutrition, the microbiome and the brain. She said abnormal eating patterns could throw off our clocks and lead to cardiovascular disease among other disorders. "Thus, it is of great importance that we pay attention to what we eat and when we eat it." she wrote via email.

Exactly how late is too late? Buijs said it's best to avoid eating after 9 p.m., which is advice that even non-dieters may want to follow.