A new study provides evidence that it is essential to maintain a regular eating routine to avoid obesity.
For many, the workweek’s end offers a welcome break from the structured routine of working days.
This offers a taste to freedom: a few days of a more flexible schedule or literally no schedule.
However, a new study finds that a more spontaneous weekend eating schedule may be associated with an increase in the level of body mass (BMI).
Authors of the study refer to the weekend diversions of people from their regular eating routine as “eating jet lag,” which they say may be as physiologically harmful as the disruption of the body that may arise while traversing time zones.
About the study
The cross-sectional analysis is part of the doctoral thesis of the University of Barcelona (UB) in Spain, by first author María Fernanda Zerón Rugerio.
The study, co-authored by other UB researchers, appears in the journal Nutrients.
The authors analyzed data from 1,106 undergraduate and postgraduate students between the ages of 18 and 25 who reported eating schedules on their weekend during the school year.
The study was conducted in 2017 through 2019. They also self-reported their height and weight — the two measurements that make up BMI.
Authors of the study say this is the first study to concentrate on the impact of meal timing shifts between weekdays and weekends on obesity.
Researchers were able to assess the average meal period of the sample over the week and weekends from the responses of the students, as well as the eating midpoint— halfway between the first and last meal of the day— for both weekdays and weekends.
They used a simple formula to calculate an individual’s overall eating jet lag value: eating midpoint on weekends minus eating midpoint on weekdays.
Certain factors that could impact BMI were accounted for by the researchers from there, including diet consistency, length of sleep, gender and chronotype.
The authors found there were higher BMI values for those with a total eating jet lag of 3.5 hours or more.
They calculated the separate eating jet lags for breakfast, lunch, and dinner using the same formula.
Not surprisingly, the meal that exhibited the greatest amount of jet lag was breakfast, given the opportunity to sleep in at the weekend.
The study showed that more than an hour of breakfast-eating jet lag was experienced by 64 percent of the participants each weekend, with this period approaching 2 hours for 22 percent of those.
There was no connection between the consuming jet lag for a particular meal and a higher BMI found by the researchers.
It is all in the timing
Eating jet lag can be the product of the same kind of dispute between the circadian rhythm of a body and irregular behavior as other types of jet lag— the sleep disturbance encountered by travelers— and “social jet lag” arising from odd weekend sleep schedules.
As the authors of the study put it, “The circadian system consists of a master clock and a network of peripheral clocks which are all hierarchically organized.”
One of the authors of the study, Trinitat Cambras of UB’s Department of Biochemistry and Physiology, further explains:
“Our biological clock is like a computer and is ready to unchain the same physiological and metabolic response at the same time, every day of the week.”
“Dynamic feeding and sleep patterns help the body coordinate itself and promote energy homeostasis.”
“As a result, when intake takes place regularly, the circadian clock ensures that the body’s metabolic pathways act to assimilate nutrients. However, when food is taken at an unusual hour, nutrients can act on the molecular machinery of peripheral clocks (outside the brain), altering the schedule and thus, modifying the body’s metabolic functions.”
– Maria Izquierdo Pulido
Further work is still needed into the link between consuming jet lag and BMI.
However, Izquierdo Pulido points out, it is already recognized that there are advantages to keeping a regular schedule. Those may now be applied by scientists to fighting jet lag.
She says, “Apart from diet and physical exercise, which are two foundations of obesity, another aspect that needs to be considered is regular eating habits, as we have seen that this has an effect on our body weight.”
