GAINESVILLE, Fla. – Americans have long heard about the health benefits of adhering to diets rich in fresh produce and whole grains and low in red meat and processed sugars.
But they may not be aware of how meal timing can affect their health.
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A recent publication from the UF/IFAS department of food science and human nutrition describes chrononutrition, an emerging field of study that connects eating with circadian rhythm, the body’s 24-hour internal clock.
How someone schedules meals throughout the day can impact their weight and body mass index (BMI) as well as increase their odds of developing cardiometabolic diseases, including type 2 diabetes, according to the authors of the publication, an Ask IFAS guide.
“Healthy eating is not only what you eat but also how much you eat and when,” said doctoral candidate Kaylyn Koons, the publication’s lead author.
Franz Halberg, a Romanian-born physician, introduced the idea of chrononutrition in 1967.
The concept is based on the premise that the sleep and wake cycle regulates bodily functions, including metabolism and digestion, so the timing, frequency and consistency of food intake affects health.
There is a broad range of eating behaviors that influence chrononutrition, according to the UF/IFAS guide.
One of the key behaviors relates to the “eating window,” the time frame between the first meal of the day and the last.
Optimizing that window – typically between 8 and 12 hours -- could realign food intake with the circadian clock.
In fact, a systematic review of studies on time-restricted eating with an eating window of 12 hours or less found an average weight loss of 3%, along with reductions in fasting blood glucose, systolic blood pressure, waist circumference, and LDL cholesterol levels.
Many eating behaviors related to poor chrononutrition center around evening food consumption. Eating at or after 8 p.m. is associated with weight gain and metabolic disorders, for example.
Potential reasons include the prevalence of poorer food choices at night and late eaters’ propensity to stay up late, which can negatively impact sleep.
Evening latency, the amount of time that lapses between eating the last meal of the day and sleeping, can also play a part, according to the guide.
It describes a 2023 study of Malaysian college students which found that those who didn’t observe a delay between eating dinner and sleeping were more likely to be underweight.
“This finding may seem counterintuitive because you might expect this behavior would reduce energy expenditure and promote weight gain rather than weight loss,” Koons said. “But it could be associated with other adverse chrononutrition habits such as skipping meals or irregular meal timing, which lead to an overall reduced calorie intake.”
Koons recommends anyone desiring to improve their chrononutrition examine their eating behaviors and identify chrononutrition-related behaviors that may be negatively affecting their health.
Then they can set attainable goals to reduce the frequency of those behaviors.
Patience is key, however, she said.
“Eating habits tend to be ingrained in routine and become habitual,” Koons said. “It’s important to remember that behavior change is difficult, and it takes time.”