Giving in to those late-night munchies won't make you gain weight after all, according to a new study.
"Eating at night is no more likely to promote weight gain than eating during the day," said study co-author Judy Cameron, a researcher at the Oregon National Primate Research Center at Oregon Health & Science University.
Cameron and her colleagues reviewed existing data on the topic and conducted new tests on rhesus monkeys.
They studied 16 female monkeys that were placed on high-fat diets similar to the diets of humans in the United States and other Western countries.
The monkeys all had their ovaries removed to mimic a menopause-like state. Combined with the high-fat diet, the decreased ovarian function caused the monkeys to gain weight.
During the year that the monkeys were observed, researchers recorded how much and when the animals ate and how much weight they gained. They found that the monkeys ate between 6 and 64 percent of their total calories at night. The researchers say this is comparable to humans who take in approximately 24 to 65 percent of their total calories at night.
The monkeys all gained weight, but no consistent pattern emerged. Those that ate more didn't necessarily gain more weight and whether the monkeys preferred to eat during the day or at night also didn't matter.
The finding suggests the common warning against snacking at night is just a popular myth.
"A person's activity level is a better predictor of weight gain and loss," Cameron said. "In other words, for those wishing to lose weight, changing your diet may not be enough."