Holiday over-eating throws off our ‘food clocks’

Pia Ranada
It’s not how much we eat during Christmas that we should worry about, but how often

HOLIDAY EAT-ALL-YOU-CAN. Be careful of not only how much you eat, but when you eat. Photos by Joaquin Carlos De Jesus

MANILA, Philippines – After the lechon has been reduced to bones on a platter, the leche flan tin plates scraped clean and the hamon wrappers crumpled on the table, an inevitable feeling of guilt washes over us. We worry that we may have eaten a wee bit too much over the holidays.

But according to a study by the University of California, San Francisco, it’s not how much we eat during Christmas that we should worry about, but how often.

Apparently, there is such a thing as a “food clock,” a collection of interacting genes and molecules that keeps our metabolism balanced by ensuring that we eat at the right time. It does this by letting us know when we are hungry, prompting us to hunt for that savory chicken breast in the refrigerator.

During the holidays, especially during Filipino holidays when everyone gives food as gifts and the ref is overflowing with food that can expire at any moment (or so we rationalize), our thrice-a-day eating schedule expands to a 24-hour eating cycle. We eat every moment we can, thinking little of it: a jar of cookies while watching TV, cupcakes while wrapping gifts, ube hopia in between.

This eat-all-you-can extravaganza tips the balance in our food clock and makes it go haywire, tricking our bodies into thinking we are hungry when we aren’t. The effect is that, every time we aren’t munching on anything, we feel starved.

The same problem happens with people who work graveyard shifts, suffer jet lag or are prone to grabbing midnight snacks. As their bodies adapt to their new, irregular schedules, their food clocks are thrown off, impairing their ability to know when they are actually hungry. Instead of eating when they should (meaning, when their bodies most need the sustenance and nutrition), they eat at random times.

Lack of PKCy

But some people have a harder time than most in adjusting their food clocks to new eating habits. According to a study by the UCSF team, this is due to a lack of a specific protein.

In their study published in the journal Proceedings of the National Academy of Sciences, they discovered that a protein called PKCy is responsible for resetting the food clock when our eating habits change.

In the study, normal laboratory mice with PKCy who were regularly fed during their normal sleeping hours eventually adapted, waking up earlier to eat. Mice without PKCy did not adapt, sleeping through meal time.

Doctors and scientists say this new study can provide fresh insight on other eating disorders such as obesity and diabetes.

So as New Year approaches, remember not only to look at your food’s nutrition chart, but also at the clock on your wall. –

Pia Ranada

Pia Ranada is a senior reporter for Rappler covering Philippine politics and environmental issues. For tips and story suggestions, email her at