Every year, somewhere around the second week of November, the five pound figure reappears. You gain five pounds over the holidays. It has the shape of a fact and the sourcing of a rumour.
In 2000, a group at the National Institutes of Health decided to check.
The short answer
No. A prospective study published in the New England Journal of Medicine weighed 195 adults four separate times across a full year and found an average holiday period gain of 0.37 kg, plus or minus 1.52 kg. That is roughly eight tenths of a pound, against a claim of five.
The researchers were direct about why they ran it at all. They noted in their own background section that the five pound assertion was commonly made and that few data supported it. So they measured it.
What 195 adults weighed four times showed
The design is what makes this study hold up. Participants were weighed at intervals of six to eight weeks, which produced three separate windows: preholiday, running from early October to mid November; holiday, from mid November to early or mid January; and postholiday, from January through to late February or early March.
Only the holiday window showed a statistically significant gain. The preholiday window came in at 0.18 kg and did not reach significance. The postholiday window showed a small loss of 0.07 kg, also not significant.
One more detail worth knowing. The researchers collected vital signs and self reported health measures alongside the weights, specifically to disguise what the study was really about. If you tell people you are studying holiday weight gain, you change their holiday.
The finding that actually matters
Here is the part that gets left out of every article that cites the reassuring headline number.
Measured against their weight in late September or early October, participants carried a net gain of 0.48 kg by the following February or March. Then 165 of them came back the next September, and their weight had not significantly changed again. The gain from the previous winter was simply still there.
The authors' conclusion says it plainly: because the gain is not reversed during the spring or summer, that net half kilogram probably contributes to the weight increase that frequently occurs across adulthood. The holidays are not a crisis. They are a ratchet.
Where the five pound number came from
Nowhere traceable, which is the honest answer. It circulated in the popular press well before anyone measured it, and the NEJM authors treated it as folklore worth testing rather than a finding worth citing.
Since then the number has been checked repeatedly. A 2014 review in Physiology and Behavior pulled together multiple studies across Western societies and reported average gains between mid November and mid January of about 0.5 kg. A later research letter in the New England Journal of Medicine looked at the same question using connected scale data across three countries, and found holiday patterns in all of them.
Different samples, different decades, same order of magnitude. The five pound figure has now survived roughly a quarter century of contradiction, which tells you something about how a good story outperforms a measurement.
Who gains more than average
Averages hide the spread, and the spread here is large. In the 2014 review the range of individual weight change was wide, and people who were already overweight or living with obesity gained more than people at a healthy weight.
The review also made a point that reframes the whole topic. When gain was tracked across the entire year, the holiday period was the major contributor to annual excess weight gain in adults. Not the only contributor, but the biggest single one. That is a different claim from the panicky version, and a more useful one: six weeks disproportionately shape twelve months.
How to read a December weigh-in
A large meal moves the scale the next morning through food mass and retained water, and that has almost nothing to do with the 0.37 kg the researchers were measuring. If you weigh yourself on December 26th and read that number as fat gain, you will be wrong and you will feel terrible about it.
The useful unit is a week, not a morning. That is not a motivational reframe, it is a measurement one. Water shifts of a kilogram or more are ordinary across a few days of different eating, and they resolve on their own.
How OffRamp handles a holiday week
This is the exact scenario Regain Radar was built around, and it is why the thresholds are shaped the way they are rather than being simpler.
The radar compares a seven day rolling average of your weight against a baseline you set. It stays quiet until that average has held at or above baseline times 1.02 for seven consecutive days. A four percent version of the same rule raises a stronger alert. A Christmas dinner cannot trigger either one, because a single day cannot hold an average anywhere for a week.
Days you do not weigh yourself carry the previous average forward rather than breaking the sequence, which matters over a holiday when nobody is logging on schedule. The design assumption is that people go quiet in late December, and a tool that punishes that with a reset is a tool people delete in January.
The protein side does not change for the holidays either. The floor is 1.6 grams per kilogram of your goal weight, rounded to the nearest 5 grams. It is a floor rather than a limit, and there is no calorie target anywhere in the app, because the thing that actually goes wrong across a heavy eating week is protein getting crowded out, not eaten to excess.
OffRamp does not give medical advice or comment on medication. If you are on or coming off a prescribed treatment, that conversation belongs with your prescriber. What the app can do is stop a single week in December from reading like a verdict on the year.
