Holiday weight gain and why it may still be there in spring

Holiday weight gain can be small on average yet persist for months. Research separates partial recovery from a full return to your earlier weight.

日本語で読む（Japanese version）

On the first morning back at work, you put on your usual clothes and step onto the scale. The number is higher than before the break. Meals and commuting are returning to normal, so surely weight will follow. You slide the scale back under the bathroom cabinet and leave the calendar to handle the rest.

Research does not treat the end of a holiday and the reversal of weight gain as the same event. In a study following adults from autumn, average holiday gain was only 0.37 kg, but subsequent measurements did not establish that the gain had been adequately reversed. An ordinary working week can resume while weight remains above its earlier level.[20]

Enjoying festive meals and paying attention to what happens afterward can fit together. The useful question is not whether a particular New Year dish is good or bad. It is what studies spanning the break actually measured: how much people gained, how much they subsequently lost, and whether attempts at prevention worked. For readers in Tokyo whose celebrations may include Christmas, Japanese New Year or both, those distinctions matter more than treating every holiday meal as a separate verdict.[1][2][20]

Average holiday weight gain can be smaller than expected

A longstanding prospective observational study compared the impression of substantial holiday gain with repeated measurements in 195 adults. Prospective means that researchers follow participants forward in time rather than asking them to reconstruct the entire period from memory. Participants were a convenience sample: people who could readily be recruited, rather than a sample guaranteed to represent all adults. They were weighed at intervals of 6–8 weeks, allowing researchers to distinguish changes before, during and after the holidays.[20]

Average gain before the holidays was 0.18 kg. During the holidays it was 0.37 kg, and afterward there was an average loss of 0.07 kg. Only the holiday-period increase was statistically significant. Its p-value was below 0.001, compared with 0.09 before the holidays and 0.36 afterward. The size of the change and the statistical assessment belong together: a small average difference can be detectable across a group, while another change may not be distinguishable from uncertainty in the data.[20]

The holiday increase also had a standard deviation of 1.52 kg. Standard deviation describes how widely individual values are spread around the average. Here, that spread was substantial relative to the mean gain of 0.37 kg. People who gained more, people who gained less and people who did not gain all contributed to the same average. The group’s central number cannot tell you what happened to your own weight over the break.[20]

A 2017 narrative review reported gains of 0.4–0.9 kg in adult studies. A narrative review reads existing studies together to describe the evidence. The college-student research it included found an effect on body fat without a significant change in weight, and evidence in children was limited. These differences are part of the result. An adult finding should not become a prediction for every member of a family simply because everyone shared a holiday table.[6]

A systematic scoping review took a broader look at festive periods and celebrations. It organized 39 studies covering weight changes, influences on eating and preventive interventions. Of the 23 observational studies examining weight change, 70% found significant increases, with an average gain of 0.7 kg reported. A scoping review maps what is known across an area; it is useful for seeing the range of questions studied, rather than turning every included result into one universal expectation.[14]

That review found only 4 studies specifically investigating exposure to food cues and overeating during celebrations, with mixed results. The number of studies measuring weight should therefore not be mistaken for equally extensive evidence about exactly why people ate more. The evidence can be clearer about a change occurring than about the particular pathway producing it.[14]

None of these averages scores the amount you ate at a year-end dinner. The research concerns changes over periods crossing the holidays. A reading the morning after one meal cannot answer the same question as measurements taken before and after the whole break. To use the research practically, start by identifying the comparison: your own earlier weight and what happens to it through the holiday period.[20]

Spring does not automatically reverse the gain

In the study of 195 adults, net gain from the autumn starting point to the following spring averaged 0.48 kg. A further measurement was obtained from 165 participants the next autumn, with no significant additional change between spring and autumn. The researchers interpreted the lack of reversal over spring and summer as a possible contribution to the weight gain that often occurs across adulthood. Returning to a busy schedule was not evidence of returning to the original weight.[20]

The spring net gain had a standard deviation of 2.22 kg, again showing considerable variation around the average. The longer follow-up also needs its own denominator: 165 of the original 195 participants returned for the next autumn measurement. The autumn results describe those returning participants. Keeping track of who was measured prevents a seemingly simple seasonal story from hiding differences in follow-up.[20]

Another perspective comes from a randomized trial involving 111 adults. A randomized controlled trial assigns participants by chance to an intervention or comparison group. In its control group, participants gained an average of 2.65 kg over the holidays, then lost an average of 1.14 kg during the 14 weeks afterward. Despite that loss, 57% of the holiday gain remained. Net gain from the preholiday visit to the end of follow-up was 1.51 kg.[8]

This is why “did the weight come off?” can be too blunt a question. Some of it did, yet the group did not return to its starting point. A lower number than the New Year peak and a return to the preholiday number are different outcomes. If the peak becomes the only reference, partial recovery can look like complete recovery. The earlier measurement gives the later one its meaning.[8]

A Romanian observational study followed 120 adults at 3 assessment points: before the winter holidays, immediately afterward and a year later. Average weight went from 68.25 kg to 69.40 kg, then to 69.45 kg at the final assessment. Body composition was estimated with bioelectrical impedance analysis, a method that uses an electrical signal through the body to estimate its composition. Estimated visceral fat area also remained at the higher postholiday level.[16]

Changes in weight were significantly associated with changes in visceral fat during the holiday period and across the full follow-up. This supports examining weight alongside fat distribution over time. It does not establish that every participant retained exactly the same amount, or that the holiday alone caused everything observed a year later. The persistent pattern was at group level in an observational study.[16]

Japanese student data need their own context

Winter celebrations overseas differ in duration and culture from Japan’s year-end and New Year break. A Japanese cross-sectional survey offers local evidence, but its participants were university students: 339 people, including 141 men and 198 women, with an average age of 19.4 years. They reported winter weight changes, time needed to return to their usual weight, diet, activity, sitting time, alcohol use and sleep.[9]

Winter weight gain was reported by 51.1% of men and 68.2% of women. Reported average increases were 2.3 kg in men and 2.0 kg in women. Among those reporting gain, 61.8% said their weight returned within 1 month, while 38.2% needed longer. These figures make recovery time a relevant question in Japan, but the weights were self-reported rather than measured by researchers over the winter.[9]

A cross-sectional survey asks about circumstances at a particular point and examines associations. It differs from weighing participants before winter and following them forward. Here, the duration of recovery depended on participants’ recollection too. Comparing these figures directly with measured overseas results cannot establish that people in Japan gain more or recover more easily. Measurement method and population differ along with geography.[9][20]

For men, longer sitting time during the holidays was associated with prolonged retention. For women, more frequent alcohol consumption and shorter sleep were associated with prolonged retention. Sitting time means time spent seated. These associations suggest useful aspects of a changing routine to notice, but they do not demonstrate that changing one of those behaviors by itself will reverse holiday gain.[9]

The findings also resist a simple list of good and bad habits. In women, winter gain itself was associated with more frequent exercise and less sitting on weekdays. Lower consumption of instant or ready-to-heat foods was associated with gain as well. These results should stay in view even if they do not fit an easy explanation.[9]

The reported gains had standard deviations of 1.2 kg in men and 1.1 kg in women, showing variation within each group. Occurrence of gain and prolonged retention were analyzed separately, with different associated factors. For daily life, the study suggests looking beyond exercise alone to changes in sitting, drinking and sleep. For interpretation, it requires keeping “did weight increase?” separate from “how long did the increase remain?”[9]

Numbers: holiday gain and recovery

0.37 kg: average holiday gain measured in 195 adults; the standard deviation was 1.52 kg.[20]

0.48 kg: average net gain from the autumn baseline to the following spring in that study.[20]

57%: share of holiday gain still retained after 14 weeks in the control group of the 111-adult trial.[8]

38.2%: share of Japanese students reporting winter gain who said recovery took longer than 1 month.[9]

−0.49 kg: adjusted average difference between groups in the 272-adult trial combining weight records and other advice.[4]