Guide October 2026 · 9 min read

How much there is to lose

Before setting a target, it helps to know what you're dealing with. When researchers actually weighed people, the holiday gain was small: about 0.8 lb (0.37 kg) on average in a US study, and about 0.5 % of body weight in a study across the US, Germany and Japan. The details and the calorie maths of the season are in how to get through the holidays without gaining weight.

The trouble is that this small gain often stays. In the US study, it was still there in February and March. So the January job isn't to lose 10 lb fast. It's to take off the pound or two that would otherwise become permanent.

The first weigh-in after New Year's usually reads higher than the real gain. Holiday food is salty, and the body holds extra water to balance the sodium. That water goes in a few days of normal eating, so judge your starting point by the average of the first week, not by the morning of January 2.

How long it takes: weight vs daily deficit

A common rule of thumb says a pound of body fat is about 3,500 kcal. Over a few weeks it's a usable estimate; over months it overstates the loss, because the body adapts and burns a bit less as you get lighter (Hall et al., Lancet, 2011). For holiday-sized goals, it's close enough.

Two things follow from this table. A typical holiday gain comes off by the end of January with a modest deficit, so there's no need for a crash diet. And a bigger deficit saves only days on a small goal, while being much harder to keep up. Most people do better at 300–500 kcal a day. How to set the number is in calorie deficit for weight loss.

A restart plan for the first two weeks

1. Day 1: weigh in and write it down. Weigh yourself in the morning, before breakfast. Then do it again for the next few days and use the average as your starting weight.
2. Days 1–7: log without cutting. Eat your normal January meals and log all of them, including snacks and drinks. After the holidays, you probably don't know your usual intake anymore. One honest week shows where the calories are.
3. Day 8: set the deficit. Take your average logged intake and subtract 300–500 kcal. That's your daily target. If the logging week also brought your weight down, the leftover holiday water is gone and the trend from here is real.
4. Cut from the obvious places first. For most people that's the leftovers of the season: the cookie tin, the chocolate box, the evening eggnog or wine. Using these up "so they don't go to waste" is how December drags into January. Give them away or freeze them.
5. Build meals around protein. Protein keeps you fuller on fewer calories and helps keep muscle while you lose fat. A palm-sized portion at each meal is a simple start. How much protein per day →
6. Look at the weekly trend, not the daily number. Weight moves up and down by a pound or more with salt, water and timing. If the weekly average goes down, the plan is working.

What a restart day can look like

Here is the base of a simple day built from foods in our calorie guides. These seven items give about 1,090 kcal and 103 g of protein. A full day at a 1,600–1,800 kcal target leaves 500–700 kcal for vegetables, cooking oil, bread, sauces and one treat.

None of these foods is special. The point is that a filling day with plenty of protein fits easily under a deficit target, without "detox" products or skipped meals.

What not to do in January

• Don't try to undo the season in a week. Eating very little after the holidays usually ends in a weekend of overeating. A loss of half a pound to a pound a week is a good pace for a holiday-sized goal.
• Don't buy a cleanse. A few days of juice or a "detox" plan is simply very low in calories and food volume, so the scale drops. The weight returns when you eat normally again, and you've learned nothing about your usual meals.
• Don't wait for the perfect Monday. If you missed January 4, start on the next ordinary day. A late start costs a few days; waiting for the "right" week costs the whole month.
• Don't stop logging after the first good week. In a review of 22 studies, people who self-monitored their diet consistently lost more weight than those who didn't (Burke et al., J Am Diet Assoc, 2011). The habit matters more than any single day. Building a food tracking habit in 4 weeks →

How to log the restart

The first week back is about getting the habit going again, so make each entry as quick as possible.

• Photograph each meal. In CalMePlease the AI identifies the dish and counts calories and macros. A short video can hold several dishes, and each lands as a separate entry.
• Say the small things. A voice note like "coffee with milk and two leftover cookies" takes a few seconds. Voice food logging →
• Scan the leftovers. Holiday chocolates and snack tins have barcodes; scanning one keeps the pack's serving size, so the "just one" from the box is counted correctly.
• Check the portion. The app shows the estimated weight in grams, and you can correct it in one tap.
• Fill in the holidays if you want a clean record. You can add a meal to any past day from the calendar. A rough entry for New Year's Eve is better than a gap.
• Set a goal and ask what to eat next. Choose a goal such as losing weight, and the built-in AI coach sees the whole day and suggests what to eat next.

FAQ

How long does it take to lose holiday weight? For an average holiday gain of a pound or two, about one to four weeks at a deficit of 250–500 kcal a day. A 5-lb gain takes about five weeks at 500 kcal a day. These are estimates based on the 3,500 kcal per pound rule of thumb.

Why did I gain 5 lb in a week over Christmas? Mostly water. Salty, carb-heavy holiday food makes the body hold more water, and that shows up on the scale right away. Fat gain is much slower: a pound of fat takes about 3,500 kcal above your needs. Eat normally for a few days and the number usually drops.

Should I fast or do a detox after the holidays? There's no need. A cleanse lowers the scale for a few days because you eat very little, and the weight comes back when you stop. A moderate deficit with regular meals is easier to keep up and takes off the actual gain.

What is a good calorie deficit to lose holiday weight? 300–500 kcal a day below your usual intake works for most people. It removes a typical holiday gain in a few weeks without leaving you hungry. Log a normal week first, so the deficit is based on what you actually eat. Calorie deficit for weight loss →

When should I start tracking again after the holidays? On the first ordinary day after New Year's. In 2027, January 1 is a Friday, so Monday, January 4, is a natural start. If you miss it, any normal day works.

Do I need to log the holiday meals I already ate? No. The restart works from today. If you want a full record, add the big dinners to the right days from the calendar with rough portions.

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Data: Yanovski JA et al., A prospective study of holiday weight gain, N Engl J Med 2000;342:861–867; Helander EE, Wansink B, Chieh A, Weight gain over the holidays in three countries, N Engl J Med 2016;375:1200–1202; Hall KD et al., Quantification of the effect of energy imbalance on bodyweight, Lancet 2011;378:826–837; Burke LE, Wang J, Sevick MA, Self-monitoring in weight loss: a systematic review of the literature, J Am Diet Assoc 2011;111:92–102. Restart-day foods: USDA FoodData Central, SR Legacy, as cited in our oatmeal, banana, Greek yogurt, chicken breast, potato, apple and salmon guides. Values checked October 2026.

Related: Holiday weight gain · Calorie deficit for weight loss · Food tracking habit in 4 weeks

CalMePlease gets you logging again in seconds: a photo of the plate, a voice note for the leftover cookie, a scan of the chocolate box. Free on the App Store.