Blame Biology for Why You Ate Your Weight in Holiday Ham


It’s no coincidence that the holiday season’s mascot is a morbidly obese guy who gorges himself on cookies. Forget about presents and obnoxious sweaters, binge-eating is the true star of December’s holiday festivities. But it’s not your fault that you keep reaching for seconds and thirds and fourths… Your biology is making you do it. Well, your biology is at least a plausible fall guy. Here’s why.

Sugar used to help keep you alive. You don’t need to know what a sugar plum is to know that sugar is in everything during the holidays. And it doesn’t just stop with pecan pies, gingerbread cookies and candy canes. Holiday dinner staples such as mashed potatoes and stuffing get broken down by the body into simple sugars as well.

We reach for them, in part, because the craving for sugar is rooted in human physiology. Long story short: Sugar provides a burst of energy and also helps store fat. That’s why, millions of years ago, when sugar was harder to come by, our ancestors evolved to prefer the taste of riper fruit, which had the highest concentration of sugar. It was basically the only place they could get a sugar fix.

But modern agriculture and food processing have allowed us to create food that’s much sweeter than even the ripest fruit—and to consume much more of it. An apple, for example, has 25 grams of sugar. Compare that to a 14-ounce can of sweetened, condensed milk, the bedrock of many holiday recipes, which has 220 grams of sugar.

Even worse, excess sugar leaves you hungry and unsatisfied. So you’re gaining weight even while you’re still ravenous. And so begins the vicious cycle of overeating.

Fatty foods are like heroin. Along with sugar-loaded foods, the holiday table is full of high-fat dishes like creamed spinach, potatoes au gratin, and the ever-present cheese log. Eating these foods unleash dopamine, which helps activate the reward centers of the brain—the same parts that light up for sex and drugs. Not surprisingly then, years of research (involving a lot of chubby, blissed-out lab rats) have shown that high-fat foods can be as addictive as cocaine or heroin.

Again, the culprit is evolution. Back when food needed to be bludgeoned to death, it wasn’t clear when the next meal would be, so we evolved to enjoy high-fat foods that would keep us full for as long as possible. But nowadays we can eat around the clock—whether we need to or not. That goes double during the holidays. Which brings us to…

Not eating is socially awkward. For many, the first big holiday meal is only the beginning. It could be that you have a meal with one divorced parent and then another meal with the other. Or a meal with the in-laws before going over to your own parents’ house. Or, it could be a pre-party fast food drive-thru situation, followed by “your first big holiday meal” at a friend’s house.

Regardless of the specific scenario, it’s easy to get pulled into a string of holiday dinners, oftentimes resulting in an unintended version of what comedian Louis C.K. calls a “bang-bang”—eating two full meals back-to-back.

There’s a seemingly simple solution to avoiding the bang-bang: Pace yourself. But in practice that’s almost impossible because, in addition to fighting back evolutionary instincts, you’ll also be wrestling with your social instinct. Each gathering hosts a new group of people who will likely be eating, and studies show that people often eat just to fit in with the others around them. Which makes sense. No one wants to be the odd man out.

So before you know it, you’re in a bang-bang. Or even a bang-bang-bang.

Ditching leftovers make you feel guilty. You’ve somehow survived the sugar highs, the slabs of honey-baked ham, the bang-bangs and the countless drinks. But then, in your post-holiday stupor, you open the fridge and think, “It sure would be a shame to let this stuff go to waste.” Indeed, of all the wasteful activities that Americans engage in routinely, throwing away food has been shown to be by far the biggest trigger for guilt.

There are a few solutions for this binge: One is to avoid cooking too much or, if that’s not up to you, taking home as little as possible. Some areas also have programs or food banks that give leftovers to the less-fortunate.

If neither of those options work for you, keep in mind that restaurants and the hospitality industry waste way more food than you do. In California alone, hotels, restaurants and caterers throw out an estimated 1.5 million tons of perfectly good food every year. So tossing out five-day-old sweet potatoes doesn’t qualify you as an awful human being.

Next year can be totally different. Human biology is also about adaptability. Your body can be trained, tricked and transformed. Yes, we’re suckers for the highest-calorie, highest-sugar foods available. But it’s also possible to condition yourself to crave healthier foods. So if you’re looking for a New Year’s resolution, consider training your mind to reach for an apple instead of an apple pie.

story by:  Joel Silberman