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Researchers say eating meals at night can affect blood sugar levels. Eclipse Images/Getty Images
  • Researchers say eating at night can disrupt blood sugar levels and increase the risk of type 2 diabetes.
  • Previous studies have shown that having meals in the evening can cause weight gain and increase the risk of cardiovascular disease.
  • Experts say people who work night or overnight shifts should try to eat meals at as close to “normal” times as possible.
  • They add that what you eat is also important, so making healthy food choices is essential.

Eating at night, out of sync with your body’s natural circadian rhythms, could put you at risk for diabetes, according to researchers from Brigham and Women’s Hospital in Boston.

That in itself isn’t new.

Previous studies have shown that nighttime eating can cause people to make poorer food choices and cause weight gain, leading to higher risks of diabetes and cardiovascular disease.

But the Brigham and Women’s study looked specifically at how eating throughout the evening affected blood sugar levels versus eating during the day.

In the study, researchers put 19 healthy young people in an environment intended to imitate night shift work

While all the study participants “worked” overnight, only those who ate their meals through the night shift saw increased blood glucose intolerance and decreased pancreatic beta-cell function — both of which are potential precursors to type 2 diabetes.

The participants who stayed on a daytime eating schedule saw none of these adverse changes, despite being up all night, researchers reported.

Previous studies have linked night shift work to increased risk of cancer, heart arrhythmia, and even miscarriage.

“These results indicate that meal timing was primarily responsible for the reported effects on glucose tolerance and beta-cell function, possibly due to the misalignment of central and peripheral ‘clocks’ throughout the body,” Frank A.J.L. Scheer, PhD, a co-corresponding author and a neuroscientist in sleep medicine at Brigham and Women’s Hospital, said in a press release.

“While the central circadian ‘clock’ was still on Boston time, the endogenous circadian glucose rhythms suggest that some peripheral ‘clocks,’ as perhaps those in the liver, had dramatically shifted to a time zone in Asia,” Scheer continued.

For people on a regular daytime work schedule, the advice here is simple: Stick to eating during the day, eat a balanced diet, and try to avoid late-night snacking.

But for the 23 million Americans who work late night or irregular shifts, the answer is not so simple.

Galina Kinel, a registered nurse based in New Orleans who has worked 7 p.m. to 7 a.m. shifts several days per week for years, said switching to eating meals during the day was difficult to do.

“If I didn’t sleep until at least 3 or 4 p.m. [after coming off shift], I would feel awful, so I think it would be difficult to eat during the day,” she told Healthline.

Here’s how she described her schedule:

“I would wake up around 4 and eat a light meal before coming into work, maybe a salad or small sandwich. I had a coffee around 7 p.m. and another one around midnight if I was lagging. My lunch would be around 1 to 2 a.m. and then I’d eat maybe a small snack around 4 to 5 a.m., because that’s when I would get sleepy.”

And what you eat matters, too — especially at night.

“Your body metabolizes food differently at night, and heavy eating may decrease your alertness and productivity. When working at night, when your body clock is disrupted, you may experience fatigue, sleep problems, poor concentration, [and] difficulty metabolizing food,” said Laura Krauza MS, RDN/LDN, a clinical dietitian at the St. Lucie Medical Center in Port Lucie, Florida.

Kinel agreed.

“When I packed myself a lunch, I felt much better than when I bought lunch at the cafeteria, which was all fried food,” she said.

She added that she and her co-workers both felt like they had put on weight working nights.

“Shift work also can negatively affect your daily habits and routines, making healthy choices more difficult,” Krauza said. “Routines can help keep us on track.”

Here’s what she recommended:

  • Try to eat meals at “normal” times.
  • Eat breakfast when you get home from a shift.
  • Eat lunch when you wake up.
  • Eat dinner before your shift.
  • Eat light snacks, and stay hydrated to help reduce fatigue at night.
  • If you feel like you need caffeine to wake up or stay alert, have a maximum of 200 milligrams 30 to 60 minutes before your shift and then every 3 to 4 hours. But stop caffeine 8 hours before sleep time.

Ultimately, however, Krauza said, “the best schedule is the one for your unique schedule.”

“Focus on healthy proteins and fiber-rich carbohydrates to maintain blood sugar and energy long term and try to eat your main meal earlier in the evening,” she added. “Fueling your body ahead of time will help you manage your hunger and energy throughout your shift.”