Intermittent fasting over the holidays

What the holidays do to your weight

Holiday weight gain is real, but smaller than people fear. In a European weight-maintenance trial, 1,062 adults weighed themselves regularly on connected scales. Over Christmas their weight rose by about 1.35% on average, and in the following months it didn't fully come back down ¹. In an American study of 195 adults, the average gain over the holiday season was 0.37 kg, far less than the 2.3 kg (5 lb) often quoted, but most of it was still there the next autumn ².

The same European data had a reassuring side too: weight rose a little at weekends and fell back during the week, once routines returned ¹. A higher number the morning after a big meal is normal, and a single day doesn't undo weeks of fasting.

A flexible holiday plan

Day	What to do with your fast
Quiet days at home	Your usual plan, such as 14:10 or 16:8
A party or late dinner	Start the timer when the meal ends, and aim for a shorter 12- or 13-hour fast
The big festive meal	Eat breakfast if you want it. You don't need to fast to earn the meal
The morning after	Back to your usual rhythm, not a longer fast to make up for it
Travel days	Eat on your destination's clock, or simply take the day off

MYTH

After a feast, you should fast for a day to cancel it out.

FACT

One meal doesn't cancel weeks of habit, and short rises in weight tended to fall back once everyday routines returned ¹. A punishing fast mostly adds hunger and guilt. Go back to your normal plan the next day; that's what keeps the habit going.

Tips for festive meals

• Drink a large glass of water before you go out, and keep one beside your drink ³.
• Start with protein and vegetables, then enjoy the rest: protein helps you feel full ⁴.
• Alcohol has calories, so it ends a fast. See does alcohol break a fast.
• Finish eating a couple of hours before bed if you can: the same meal raises blood sugar more in the evening than in the morning ⁵.
• Protect your sleep. After two short nights, healthy young men felt 24% hungrier ⁶.

Travelling

Long journeys, early flights and new time zones make fasting harder, and it's fine to pause your plan on a travel day. If you'd like to keep going, start your fast after your last meal and break it with breakfast at your destination's time. Meals help set the clocks in your body's organs ⁷, so eating on local time from the first day is a sensible habit.

Fasting Tracker over the holidays

Switch to 13:11 or 14:10, both free in Fasting Tracker, for the festive weeks. If you forgot to start the timer after dinner, you can back-date the fast or log a past one later. And the weight chart draws a trend line through your weigh-ins, so one high morning after a feast doesn't steal the show. When you're ready for longer fasts again, how to break a fast helps you ease back in.

Sources

1. Turicchi J, O'Driscoll R, Horgan G, et al. Weekly, seasonal and holiday body weight fluctuation patterns among individuals engaged in a European multi-centre behavioural weight loss maintenance intervention. PLoS One. 2020;15(4):e0232152. doi.org/10.1371/journal.pone.0232152
2. Yanovski JA, Yanovski SZ, Sovik KN, et al. A prospective study of holiday weight gain. N Engl J Med. 2000;342(12):861-7. doi.org/10.1056/NEJM200003233421206
3. Dennis EA, Dengo AL, Comber DL, et al. Water consumption increases weight loss during a hypocaloric diet intervention in middle-aged and older adults. Obesity (Silver Spring). 2010;18(2):300-7. doi.org/10.1038/oby.2009.235
4. Leidy HJ, Clifton PM, Astrup A, et al. The role of protein in weight loss and maintenance. Am J Clin Nutr. 2015;101(6):1320S-1329S. doi.org/10.3945/ajcn.114.084038
5. Morris CJ, Yang JN, Garcia JI, et al. Endogenous circadian system and circadian misalignment impact glucose tolerance via separate mechanisms in humans. Proc Natl Acad Sci U S A. 2015;112(17):E2225-34. doi.org/10.1073/pnas.1418955112
6. Spiegel K, Tasali E, Penev P, et al. Brief communication: Sleep curtailment in healthy young men is associated with decreased leptin levels, elevated ghrelin levels, and increased hunger and appetite. Ann Intern Med. 2004;141(11):846-50. doi.org/10.7326/0003-4819-141-11-200412070-00008
7. Wehrens SMT, Christou S, Isherwood C, et al. Meal Timing Regulates the Human Circadian System. Curr Biol. 2017;27(12):1768-1775.e3. doi.org/10.1016/j.cub.2017.04.059