The Science of Holiday Weight Loss and Weight Maintenance

Statistics on weight gain in the U.S. can give the impression that it is happening everywhere, to everyone, and in every season of the year. The best science on the subject, however, reveals that weight gain primarily occurs in a smaller and predictable set of circumstances. Surprisingly, these circumstances frequently defy conventional beliefs about how and when weight gain occurs. For example, working adults yearn for weekends, purportedly for greater recreation, yet research shows that we become less active and gain more weight on weekends versus weekdays (1). Similarly, schools often receive criticism for their role in childhood obesity – usually directed towards school lunch quality and lack of PE classes – yet longitudinal data indicate that the strongest predictor of a child developing obesity during their school years is being overweight before entering kindergarten (2) and that fitness declines and weight increases are more common during the summer months instead of the school year. Despite decades of research, these kinds of mistaken beliefs about weight gain remain remarkably popular and resistant to correction (3).

Perhaps the weight gain circumstance where conventional beliefs are most accurate is the widely held view that holiday weight gain is common in the U.S. The best prospective research affirms that adults gain more weight during the November-January holiday interval relative to the rest of year (4). However, even this rare instance of weight gain opinions aligning with science comes with conditions. What is the condition? That the average weight gain is .48 kilograms (converting to 1.06 pounds if your calculator isn’t handy). This seemingly trivial pound of weight gain, however, is generally maintained the rest of the year, slowly accumulating over time for the average adult.

Source: Pixabay: TeroVesalainen

Rarely discussed in all the above research is the consistency of weight gain occurring in a one-sided pattern. Specifically, in most of the circumstances where weight gain reliably occurs, it primarily occurs among those already struggling with their weight. Adults with overweight and obesity are the least active and most weight gain-prone on weekends; Children who are overweight entering school are at highest risk of unhealthy weight gain across both their school years and during the summer months; and, finally, adults with excess weight are those most prone to gain weight during the holidays. This pattern can seem unfair and even cruel; thankfully, it also comes with explanations that can be useful to us. Firstly, weight gain science is a persuasive reminder that it is easier to prevent excess weight gain than to lose excess weight afterwards. The human body possesses an assortment of mechanisms designed to resist weight loss that we are best off avoiding when the option is available. Secondly, there is considerable variability in holiday weight gain patterns among the normal weight and overweight that are largely explained by different behavior patterns. It is both encouraging and instructive to consider holiday weight gain to be the result of modifiable behaviors than some sort of predetermined metabolic destiny.

Although tips about preventing holiday weight gain dominate the internet this time of year, the sad truth is that little of this advice has any empirical support. Mostly, these tips consist of well-intended but unsubstantiated opinions from “experts”, being about as useful as a Dr. Oz supplement recommendation. Many holiday tips are simply repackaged generic advice about weight loss that do not consider the unique challenges of the holiday season or possess any evidence to suggest whether or how they apply during this time of year. Some tips, finally, are more sinister, acting as disguised sales pitches intended to help you shed excess weight from your wallet or purse. A person determined to get the best results should settle for neither of these sources of information. For those committed to improving or at least maintaining their weight and fitness during the holiday season – and wary of this minefield of advice from the media and internet – What are the highest quality scientific recommendations?

1). Increase physical activity levels ABOVE normal. In the same seminal study from the New England Journal of Medicine that shed light on holiday weight gain patterns, the authors observed a linear relationship between physical activity patterns during the holidays and their weight changes during the same period. Predictably, those who became less active during the holiday season gained the most weight (about 50% more than average). More surprising was that maintaining a normal activity level also did not prevent weight gain. Those who kept up their regular activity levels gained only slight less weight on average than the overall group. The only group in which weight loss occurred during the holiday period were those reporting being “much more active” than usual. Unfortunately, the authors didn’t quantify the meaning of “much more”, leaving us to fill in the blank ourselves. As a health scientist, I translate “much more” to 50%+ more activity than normal; for example, aiming for 7,500 steps/day instead of 5,000 for the moderately active, and 15,000 steps/day instead of 10,000 for the more active.

2) Weigh yourself AT LEAST 2-3 times per week. In independent treatment studies published in 2018 and 2019, regular weighing was shown to effectively prevent holiday weight gain (5). This makes sense for several reasons. Typically, people avoid the scale even more than usual during the holidays and “ignorance is bliss” does not apply when it comes to preventing holiday weight gain. Instead, research suggests we adopt a “knowledge is power” mentality. Doing the opposite of the norm by weighing ourselves anywhere from daily to at least 2-3 times/week provides us with feedback about weight gain/weight loss trends while they are small and easily correctable. The 2019 study authors took this a step further than others by combining daily weighing with a graphical display of the results to provide people with an even more potent form of feedback.

3) Use HOLIDAY-SPECIFIC tips and information. In contrast to the generic weight loss advice proliferated by the media this time of year, authors of a 2018 clinical trial from the journal, BMJ (6), showed that holiday-tailored advice and information (e.g., providing calorie information for common holiday foods and drinks, and minutes of walking/running required to burn those calories) prevented holiday weight gain compared to a control group provided with standard healthy lifestyle information.

The next time you see a headline titled “twenty tips to prevent holiday weight gain”, and you almost certainly will, consider that few or even none of these tips have any proven merit. Instead, we can more confidently set and achieve our holiday weight goals by adopting specific strategies shown to work in quality research.