What time of day you eat could make a difference when it comes to cancer. A new study of from Spain that was done from 2008-2013 on 1,826 people who had either prostate cancer or breast cancer and 2,193 people who did not asked about how close to bedtime people ate meals. The study was published in the International Journal of Cancer in July.
What it found was that people who didn’t eat within two hours of their bedtime had a 20 percent decreased risk for prostate cancer and breast cancer. They also found a similar reduction in people who ate before 9 p.m. verses people who ate after 10 p.m.
Why would that timing matter? The study researchers seemed to think it had to do with the body’s circadian rhythms and their disruption. Dr. Vivian Cline, an oncologist at St. David’s Medical Center and Texas Oncology, says that like many studies, it brings up more questions than they answer, but this study had a large number of participants and it was asking participants to go back multiple years to look at their lifestyles.
We’ve already known that smoking is a risk factor, but studies are also looking at things like excess body weight and exercise, and like this one circadian rhythms. Other studies revealed that people who work nights have an increased cancer risk — again thought to be about the disruptions in circadian rhythms, Cline says.
We aren’t talking about eating late at night once or working an overnight shift once, she says. “We’re talking about habitual late-night eating.” With night-shift employees, doctors found it disrupted their glucose, cortisol and leptin levels. These workers also had a higher level of inflammation. All of this speaks to increases in cardiometabolic diseases and cancers.
“A lot of factors go into cancer,” Cline says, “It’s a dance between genetics and environment.”
While we can’t really do much about our genetics, “you can do something about your environment.”
So, why would eating less than two hours before going to bed mess with the circadian rhythms. “It’s intuitive,” she says. “When you eat a lot and go right to bed, you don’t sleep as well.”
For her patients with cancer already, Cline says if they are complaining about heartburn and not being able to sleep, she might recommend not eating within two or three hours of going to bed to see if that helps before adding another pill to their regimen.
For patients who are coming to her before they have cancer because of their heightened risk factors, she now might recommend not eating within two hours of going to bed in addition to talking to them about excess body fat, glucose levels and definitely smoking.
Smoking is still the No. 1 risk factor and the No. 1 thing she counsels against, followed by excess weight, increasing physical activity and healthier diet.
Sometimes that means having a nonjudgmental, yet tough conversation about weight. “Let’s look at your diet and reduce fat, salt and sugar and exercise regularly so you’re not in my office for a cancer diagnosis,” she says. “We need to try to make me obsolete.”
While eating late won’t move to the top of that list of risk factors, it is something that she says she’ll now talk to her patients about.