Christmas Day is optional
Skip logging it or log one rough number: here's what each does to your averages. And why the scale is up on the 26th: a USDA-built Christmas dinner weighs 1.3 kg, glycogen is stored with three to four times its weight in water, and an NIH study measured what the whole season adds.
You don’t have to log Christmas Day. Nothing in Macroline breaks if you skip it. But “optional” works best when you know what each choice does, and what the scale will say the next morning either way. So here are both, with the numbers.
What skipping does, and what one rough number does
Macroline’s History screen and weekly recap both average over the days you logged. A day with no entries isn’t counted as zero. It’s left out.
So if you skip Christmas, that week is averaged over six ordinary days. Nothing is lost, but the week’s average will look better than the week was. If you’d rather keep the record honest, log the day as one rough, generous number and close the app. The Thanksgiving math post makes the full case for that: a high estimate is a small error in a known direction, and a blank day is a gap.
Both are reasonable. What matters is knowing which one you picked when you look back at December.
Two smaller things a skipped day touches. On the iPhone, the Today screen counts how many of the last seven days you logged, so for the week after Christmas it reads 6 of 7. On the web, History also counts a streak of consecutive logged days, and a skipped day restarts it. Neither changes your averages.
Why the scale is up on the 26th
We built a Christmas dinner from USDA reference records, the same way we built the Thanksgiving plate. The portions are USDA’s standard measures, not a claim about how much anyone eats. The FDC ID is next to each food so you can look it up yourself.
| Item | Portion | Weight | Calories |
|---|---|---|---|
| Ham, roasted (168356) | 6 oz | 170 g | 301 |
| Mashed potatoes, whole milk and margarine (170037) | 1 cup | 210 g | 237 |
| Green beans, boiled (169141) | 1 cup | 125 g | 44 |
| Turkey gravy (171568) | ¼ cup | 60 g | 30 |
| Dinner rolls (172793) | 2 rolls | 56 g | 174 |
| Pumpkin pie (172788) | ⅛ of 9” | 155 g | 316 |
| Eggnog (171258) | 1 cup | 254 g | 224 |
| Red wine, Merlot (171925) | two 5 fl oz glasses | 294 g | 244 |
| Total | 1,324 g | 1,570 |
Three different things come out of that table, and the scale on the 26th mixes them together.
The weight of the meal itself: 1.3 kg, about 2.9 lb. A bathroom scale measures mass, and not all of that has left your body by the next morning. Part of any jump on the 26th is simply dinner, still on its way through.
The water that comes with carbohydrate. The body stores carbohydrate as glycogen, in the liver and muscles, and glycogen is stored “in hydrated form (three to four parts water)” (Kreitzman, Coxon and Szaz, 1992). A carbohydrate-heavy day refills those stores, and the water comes along. Potatoes, rolls, pie and eggnog all count. That’s weight on the scale that isn’t fat, and it leaves as the stores get used.
The energy: 1,570 calories, for dinner alone. That part is real, and it’s what your History average reflects if you log the day. It’s also one day. A day that runs 1,400 calories over your usual moves your 7-day average up by 200 calories a day for that week, and does nothing else.
So the morning-after number says more about dinner and water than about fat. If you weigh yourself every day, expect a jump and read it as that. If you’d rather not see it, skip the scale for a few days. Your trend will still be there when you come back to it.
What the whole season adds
The best measurement we know of comes from researchers at the US National Institutes of Health. They weighed 195 adults before, during and after the holidays. Between mid-November and early or mid-January, the average gain was 0.37 kg, about 0.8 lb (Yanovski et al., 2000). That’s far less than the “5 pounds over the holidays” that gets repeated every December.
The same study has a less comfortable finding, and it’s the useful one. The gain wasn’t lost afterwards. Participants who came back the following autumn hadn’t dropped it, and the authors conclude that small gains like this probably contribute to the weight many adults put on over the years.
Put the two findings together and the picture is simple. One day, even a big one, is a blip on the scale and a small bump in an average. What decides how the season goes is the weeks around it, and that’s the part a tracker is for.
If you do log it
Describe the dinner in a sentence. “Two slices of ham, mashed potatoes with gravy, green beans, two rolls, a slice of pumpkin pie, a cup of eggnog and two glasses of red wine.” Describe with AI turns that into items matched against our catalog, and nothing is logged until you’ve checked them and confirmed. Free accounts get three of those a day.
Or search the rows above. Every item in the table is in the catalog, and its badge names USDA as the source.
Or log one generous round number and close the app.
Whichever you choose, your diary keeps the numbers as they were when you logged them. Nothing rewrites Christmas later.
Every calorie and gram figure is from a USDA FoodData Central SR Legacy record, scaled to the portion shown and checked against USDA’s API on 2026-09-28. FDC IDs are listed with each item; look one up at fdc.nal.usda.gov. The study figures are from Kreitzman, Coxon and Szaz, Am J Clin Nutr 1992;56(1 Suppl):292S–293S, and Yanovski et al., N Engl J Med 2000;342:861–867. The History and weekly-recap behaviour is how Macroline computes it as of the same date. Macroline is not medical advice. If you have diabetes, a history of disordered eating, or another condition that depends on consistent daily monitoring, follow your clinician’s guidance over this post.