December 17, 2012 | 5 minute read

It’s that time of the year when we’re inundated with endless family feasts, work parties, eggnog, and chocolate covered everything. We celebrate a figure who consumes millions of calories of cookies in a single night, whose stomach shakes like a sandwich topping, and whose employees’ dietary staple is the candy cane. Food and drink are constantly on the brain.

We’ve been repeatedly told that we’ll be carrying around at least 5 extra pounds after the damage is done. As Yanovski and colleagues note in the New England Journal of Medicine, this message has been perpetuated by certain news outlets and medical associations alike. This year is no exception, with bad science reinforcing the idea to sell product. There are in fact no studies that show, on average, that this much weight gain occurs. It would be surprising if they did, given that the average annual weight gain is fewer than 2 pounds. Even so, that doesn’t preclude a risk of holidays on weight, and given the strong links between weight gain and cancer it is worth an exploration of the research.

By my count, there are 9 studies on weight gain over Thanksgiving or the whole holiday period (Thanksgiving through New Year’s Day), however most have low numbers of participants, are in specific populations (like college students), or are too short to draw definitive conclusions.

The best designed and likely most representative study is the aforementioned by Yanovski and others, published in 2000. They tracked 195 participants from prior to Thanksgiving through the spring, and followed a subset for a full year. The average weight gains in each period:

Preholiday (September/October to mid-November): + 0.4 pounds

Holiday (mid-November to January): + 0.81 pounds

Postholiday (January to February/March): – 0.15 pounds

Net weight change: + 1.1 pounds

N Engl J Med 2000; 342:861-867. March 23.

So the average weight gain was only about .8 pounds over the holidays. Over half of the participants in this study either gained or lost less than 2.2 pounds, and less than 10% gained more than 5 pounds.

N Engl J Med 2000; 342:861-867. March 23.

One hundred and sixty-five of these people were measured through the next fall to complete 1 full year, and gained on average a little less than half a pound more, bringing the total average weight gain in 1 year to just under 1.4 pounds. The holiday weight gain of this subset of people was about 0.7 pounds, so about half of the yearly weight gain occurred during the month and a half holiday period.

When participants were classified by their Body Mass Index (BMI) at the start of the study, the proportion of participants who gained at least 5 pounds was greater as starting BMI increased, although this only approached statistical significance (p = 0.06). It should be noted that overall, BMI was not correlated to weight change.

This increased risk for weight gain over the holidays in overweight or formerly overweight people has been observed in college populations by Hull and colleagues (2006) in two separate studies, in obese patients in a weight loss program by Andersson and Rössner (1992), and in individuals from the National Weight Control Registry by Phelan et al. (2008).

That last study explored the differences in behaviors between people who have lost weight and kept it off and those without a history of obesity. The former group was more strict over the holidays: they planned to control food intake and exercise, practiced greater restraint, ate breakfast and exercised more, but depressingly still gained more and were less likely to lose it after the holidays. Even so, these behaviors probably helped.

Until there are studies specifically studying how effective various strategies are, we can only speculate on what to do to hold off that holiday weight. But some research suggests the following are effective for periods of high-calorie and high-sedentary challenge:

•    Maintaining a food diary with calorie counts

•    Self-weighing and recording

•    Maintain an activity schedule

These types of self-regulation activities have some efficacy support from a study by Boutelle and colleagues over Christmas (1999).

•    Plan ahead: don’t go to gatherings with endless high-calorie foods on an empty stomach

•    Eat breakfast

Holidays are clearly a risk factor for weight gain, and a significant amount of annual gain appears to occur in the short month and a half from just before Thanksgiving through New Year’s. Because the weight gain is typically well below the commonly believed 5 pounds, it is probably not noticeable to most of us. In addition, those who are formerly or currently overweight tend to have more difficulty fending off weight gain for reasons not yet understood. Actively engaging in self-regulating behaviors can improve the odds against this dark side of the holidays.

Colby Vorland is a food and nutritional science graduate student. He blogs about various research topics in nutrition at http://www.nutsci.org and on Twitter @nutsci.