Weekend Weight Gain: Why Your Weight Is Up on Monday
By The Periscope Team · · 4 min read
Weight rising over the weekend and falling during the week is a normal pattern in studies of daily weighers. Most of a Monday jump is water, stored carbohydrate and food, not fat, and it usually fades by Friday. Holidays differ: average gains are around a pound, far less than the claimed 5, but often aren't lost afterward.
Key takeaways
- In daily-weighing studies, weight is usually highest on Sunday and Monday and lowest around Friday, and the average weekly swing is about 0.35% of body weight.
- People who lose or maintain weight show the biggest weekday drop after the weekend; the pattern is weakest in people who slowly gain.
- By the rough 3,500-calories-per-pound rule, a 3-pound Monday jump would take over 10,000 extra calories as fat, so it's mostly water, glycogen and food.
- Average holiday weight gain in most studies is about 0.4 to 0.5 kg (around a pound), with wide individual differences, and much of it is still there months later.
- Compare Monday with last Monday, or use a weekly average or trend line, rather than comparing Monday with Friday.
In this article
General information, not medical advice. If something about your weight worries you, talk to a doctor. How we write these articles
Weekend weight gain is one of the most consistent patterns in daily weighing data: weight rises from Saturday, peaks on Sunday or Monday, then drifts down through the week. So if you were careful all week, had a nice weekend and the scale says you're 2 or 3 pounds heavier on Monday, very little of that is fat.
The easiest way to stop Monday from ruining your week is to judge your trend weight rather than scale weight. A weight trend calculator will smooth a few weeks of weigh-ins for you, and the weekend bumps mostly disappear.
Is weekend weight gain normal?
Yes. Researchers in Finland analyzed 4,657 daily weigh-ins from 80 adults and found a clear weekly cycle. Weight started rising on Saturday, was highest on Sunday and Monday, and began falling on Tuesday. Their conclusion was blunt: weekend-weekday differences "should be considered as normal instead of signs of weight gain."
A larger study of 1,421 adults in the UK, Denmark and Portugal found the same shape, with an average swing across the week of about 0.35% of body weight. At 180 pounds that's roughly 0.6 pounds for the group as a whole. Your own weeks can swing much more.
The interesting part is who showed the pattern most. In the Finnish data it was strongest in people who lost or maintained weight. They didn't avoid weekend bumps; they came back down afterward. People who slowly gained over time tended not to.
How much of a Monday jump is fat?
Very little. Most of it is water, stored carbohydrate and food that hasn't passed through yet.
The old rule of thumb says a pound of fat is about 3,500 calories. Kevin Hall at the NIH has shown that's only a rough approximation, and it overestimates weight change over longer periods. For one weekend it's a fair ballpark.
Take an illustrative weekend (made-up numbers): a restaurant dinner, a couple of drinks, dessert and a big Sunday breakfast add up to about 1,500 calories more than you burned. That's roughly 0.4 pounds of fat. Yet Monday shows 3 pounds more than Friday. The rest comes from here:
| What changed | Why it adds weight | Fat? |
|---|---|---|
| More carbs (bread, pasta, dessert, drinks) | Glycogen is stored with at least 3 g of water per gram (Fernández-Elías 2015) | No |
| Saltier food | A salty diet is a common cause of fluid retention (NHS) | No |
| Bigger, later meals | Food and drink weigh something until digested and passed | No |
| Calories beyond what you burned | Stored, partly as fat | Some, about 1 lb per 3,500 kcal |
The first three rows fade over a few days of ordinary eating, which matches the Tuesday-to-Friday drop in the studies. For the full list of causes, see why your weight jumps day to day.
What about holiday weight gain?
Holidays are where a weekend-style bump can turn into something that sticks. The average gain is smaller than people think, but it often stays.
| Study | Who | Period | Average gain |
|---|---|---|---|
| Yanovski 2000 | 195 US adults | Mid-November to early or mid-January | 0.37 kg (about 0.8 lb) |
| Schoeller 2014 (review) | Several Western studies | Mid-November to mid-January | About 0.5 kg (about 1.1 lb) |
| Turicchi 2020 | 1,062 European adults maintaining weight loss | Christmas period | 1.35% of body weight |
| Kaviani 2019 (control group) | US adults, no intervention | Before Thanksgiving to after New Year | 2.65 kg (about 5.8 lb) |
The NIH study by Yanovski and colleagues set out to test the claim that Americans gain 5 pounds or more over the holidays. The average was under a pound. But the gain hadn't been reversed by the following fall, and the authors suggested it may help explain the slow weight creep of adulthood. Schoeller's review agreed: small on average, wide individual range, and a big share of a typical adult's yearly gain. In the European study, the Christmas gain wasn't fully lost in the months that followed either.
The Kaviani trial is the outlier, and the only randomized one. One group weighed daily on a Wi-Fi scale, saw a graph and tried to stay at their starting weight; the control group didn't. The controls gained 2.65 kg and still carried 57% of it 14 weeks later. The daily weighers didn't gain. It's one trial, so don't lean on the exact numbers, but it fits the wider evidence on how often to weigh yourself: watching the trend through a risky stretch helps people adjust early.
How should you read your weight on a Monday?
Don't compare it with Friday. You're measuring the top of the weekly cycle against the bottom, so it will nearly always look worse than it is.
- Compare like with like: Monday with last Monday.
- Average each week's weigh-ins and compare weeks. Every week has a weekend in it, so the bump cancels out.
- Watch a smoothed trend line. One weekend barely moves it; what matters is the direction over two to four weeks.
- If you're not sure a Monday jump is real, check again on Thursday.
Periscope's weekly report card shows a trend line and your rate of change per week, which makes that week-to-week comparison quick.
If the trend keeps climbing week after week, weekends may be outweighing weekdays. That still isn't a reason to crash diet on Monday. In the Finnish study, what set the successful people apart was how far they came back down during the week. Small changes that make weekends a bit less different from weekdays, like one fewer drink or a normal Sunday breakfast, tend to be easier to keep than a strict Monday.
Sources
- Orsama AL, et al. Weight rhythms: weight increases during weekends and decreases during weekdays. Obes Facts. 2014. https://pubmed.ncbi.nlm.nih.gov/24504358/
- Turicchi J, 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. https://pubmed.ncbi.nlm.nih.gov/32353079/
- Hall KD. What is the required energy deficit per unit weight loss? Int J Obes. 2008. https://pubmed.ncbi.nlm.nih.gov/17848938/
- Thomas DM, et al. Can a weight loss of one pound a week be achieved with a 3500-kcal deficit? Commentary on a commonly accepted rule. Int J Obes. 2013. https://pubmed.ncbi.nlm.nih.gov/23628852/
- Fernández-Elías VE, et al. Relationship between muscle water and glycogen recovery after prolonged exercise in the heat in humans. Eur J Appl Physiol. 2015. https://pubmed.ncbi.nlm.nih.gov/25911631/
- NHS. Oedema (swelling). https://www.nhs.uk/conditions/oedema/
- Yanovski JA, et al. A prospective study of holiday weight gain. N Engl J Med. 2000. https://pubmed.ncbi.nlm.nih.gov/10727591/
- Schoeller DA. The effect of holiday weight gain on body weight. Physiol Behav. 2014. https://pubmed.ncbi.nlm.nih.gov/24662697/
- Kaviani S, et al. Daily self-weighing to prevent holiday-associated weight gain in adults. Obesity. 2019. https://pubmed.ncbi.nlm.nih.gov/31119881/
Frequently asked questions
How long does it take to lose weekend water weight?
Usually a few days. In daily-weighing studies, weight typically starts falling on Tuesday and keeps dropping until late in the week.
Does alcohol cause weekend weight gain?
Drinks add calories, and nights out often come with saltier, carb-heavy food that holds water. The next-morning number reflects all of that, not only the alcohol.
Should I eat less on Monday to make up for the weekend?
There's no need. People who lose or maintain weight in the research tend to drift back down during the week on their normal routine, so getting back to that routine is enough.
Is it better to weigh on Friday?
Only if you always weigh on Friday. A Friday reading will usually look lower than a Monday one, so mixing days gives you a misleading picture.
Track the trend, not the noise
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