Scientists at the Oregon National Primate Research Center at Oregon Health & Science University believe they have helped dispel the myth that late-night eating causes weight gain. The research is published in the current edition of the journal Obesity Research.
"We've all been told at one point in our lives that we should avoid late-night snacks as they will lead to weight gain. In reality, however, this belief is not based in fact. We conducted a review of previous data on the topic and found no real evidence that this was true. In addition, our research in rhesus monkeys, which are considered an excellent model for studying primate (man and monkey) obesity issues, showed that eating at night is no more likely to promote weight gain than eating during the day," said Judy Cameron, Ph.D., a senior scientist in the Divisions of Reproductive Sciences and Neuroscience at the OHSU Oregon National Primate Research Center. Cameron also is a professor of psychiatry at the University of Pittsburgh.
To conduct this research, scientists studied 16 female rhesus monkeys that were placed on a high-fat diet similar in composition to the diet normally consumed by humans in the United States and other Western countries. During the study, all of the monkeys had their ovaries removed -- this simulates a menopause-like state in female monkeys similar to human female menopause. In lower animals both high fat diet and decreased ovarian function lead to weight gain.
The researchers then observed the monkeys for one year. In addition to studying their weight gain, researchers noted how much and when the animals ate, which varied dramatically among the animals observed. Specifically, the researchers found that the monkeys ate between 6 percent and 64 percent of their total calories at night. This is comparable to reports in humans who take in approximately 24 percent to 65 percent of total calories at night.