Popular belief holds that the average American gains somewhere between 5 and 10 pounds over the holiday season (Thanksgiving to New Year's Day). A few studies over the last decade, though, have found that we're not nearly as gluttonous as we think we are.

After weighing 94 graduate and undergraduate students at the University of Oklahoma before and after their Thanksgiving break, researchers found that the students gained, on average, only 0.5 kg or 1.10 pounds.

When the researchers stratified the students by gender, class standing and BMI category (either normal or overweight/obese), they found that males gained more weight than females (0.6 kg or 1.32 lb), graduate students gained more weight than undergrads (0.8 kg or 1.76 lb) and students classified as overweight by their by BMI gained more than students with normal BMIs (1.0 kg or 2.20 lb).

Another study by the National Institutes of Health repeatedly weighed 195 volunteers (mostly employees of the NIH in Maryland) during the period between late September and early March.

Between late September and mid-November, there was a mean weight gain of 0.18 kg or 0.39 lb. During the mid-November to mid-January holiday period, the mean weight gain was 0.37 kg or 0.81 lb. During the remainder of the study period, there was actually a mean weight loss of 0.07 kg or 0.15 lb. Total average gain for the whole study period was 0.48 kg or 1.05 lb (slightly less than the Oklahoma students had gained during Thanksgiving break alone). A few outliers (about 9% of the participants) gained at least 2.3 kg or 5.07 lb over the mid-November to mid-January holiday period.

The majority of participants were weighed again after the initial study period in the following September or October, where the researchers found that not only were those holiday pounds not lost, there was an additional average weight gain of 0.21 kg or 0.45 lb.

What are the takeaways from this research?

1. You will probably gain some weight this Thanksgiving (and some more during the December holidays).
2. It will not be as much as you might think (when participants in the NIH reported their perceived weight gain, it was usually four times as much as they had actually gained).
3. Although the average weight gains in these studies were modest, the NIH researchers did find that these gains were not reversed over the summer, so all those extra drumsticks might just catch up with you over the course of a few years.