Women wanting to protect their heart, should eat most of their calories earlier in the day, a new study suggests.
Researchers found heart disease risk factors worsened when a large proportion of daily calories were consumed after 6 p.m., and even more so, after 8 p.m., according to a report presented at the American Heart Association’s Scientific Sessions 2019.
When women — and men, to a lesser degree — eat their biggest meal at night, they are fighting their biological clocks, said the study’s lead author, Nour Makarem, an associate research scientist at the Columbia University Irving Medical Center.
“We evolved to adopt a 24-hour light and dark cycle, meaning we eat and are active during the day and we sleep at night,” Makarem explained. “But our more demanding work schedules and commutes push everything later and now we are eating at unconventional times.”
If we’re eating late at night, we’re not metabolizing the food as well as we would during the day.
While the master clock in the brain controls many functions, “individual organ systems, including the digestive system, have their own clocks,” Makarem said. “When the clocks in the organs become misaligned with the master clock in the brain, it creates a state of metabolic dysfunction, which can increase the risk of heart disease.”
In fact, other studies have shown that “glucose tolerance is better during the day than at night,” Makarem said. “If we’re eating late at night, we’re not metabolizing the food as well as we would during the day.”
While Makarem and her colleagues haven’t yet done the research to determine the optimum number of calories consumed after 6 p.m., she is currently recommending that they be less than 30 percent of the daily total.
According to government guidelines, estimates range from 1,600 to 2,400 calories per day for adult women and 2,000 to 3,000 calories per day for adult men.
To explore whether the timing of dinner made a difference for the risk of heart disease, Makarem and her colleagues recruited 112 women whose average age was 33. The researchers rated each woman’s health at the beginning of the study, using the American Heart Association’s Life’s Simple 7, a checklist of recommendations meant to help individuals improve their heart health, such as smoking status, physical activity, cholesterol and blood pressure.
The women were asked to keep an electronic food diary by computer or cell phone and to report on how much and when they ate for one week at the beginning of the study and then again for one week 12 months later.
While most of the women consumed some food after 6 p.m., those who ate a higher proportion of their daily calories in the evening had poorer heart health.
Every 1 percent increase in calories consumed after 6 p.m. was associated with a worse score by the Life's Simple criteria — a higher BMI, higher blood pressure and higher longterm blood sugar levels.
The good news, Makarem said, is that “a relatively simple and modifiable behavior can lower the risk of developing heart disease.”
The new report underscores how important timing is, said Dr. Elizabeth Piccione, an assistant professor of medicine at the University of Pittsburgh and a cardiologist with the UPMC Heart and Vascular Institute.
Is heart disease preventable?
Just a few weeks ago we learned that the risk of heart disease and death could be lowered by just taking blood pressure medications at bedtime rather than the morning, Piccione said.
“Simple things like taking your blood pressure medication later and eating most of your calories earlier are interventions that are not going to overwhelm us like daily life maybe already does,” Piccione said.
The study reminds everyone that food is simply fuel, said Dr. Suzanne Steinbaum, director of Women’s Cardiovascular Health and Wellness and Prevention at Mount Sinai in New York.
“We are eating throughout the day to sustain our bodies,” Steinbaum said. “If we are eating the majority of our calories after 6, we are not eating to sustain ourselves since we are just going to sleep soon. The concept of a big dinner is not physiologic, it’s social.”
It’s important to remember, Steinbaum said, “80 percent of the time heart disease is preventable. It’s really due to lifestyle choices we make. And it’s incredibly empowering to have an understanding of what you can do to stay as healthy as you can.”