Why Am I Not Losing Weight? 7 Reasons the Scale Stalls in a Calorie Deficit (and How to Check in Suu)
Published: September 27, 2026 · Furkan Mert Fındıklı · 8 min read
Short answer: If you're in a calorie deficit but not losing weight, the most common reasons are eating more than you log (especially drinks, snacks and weekends), overcounting exercise calories, water swings on the scale and energy needs that fall as you lose weight. Look at the 3–4 week average before deciding anything. In Suu, your whole day — drinks included — sits on one screen.
You've been careful for weeks, you believe you're in a calorie deficit, yet the scale won't budge. Almost everyone trying to lose weight goes through this, and it usually ends in the conclusion "my metabolism is broken."
In reality the causes are usually more ordinary — and measurable. Below we first check whether the plateau is real, then go through the seven most common reasons one by one.
First: has the scale really stalled?
Body weight can swing 1–2 kg (2–4 lb) within a day and from day to day; salt, carbs, water, digestion and the menstrual cycle are the main drivers. In one study, weight rose over the weekend (Saturday to Monday) and fell during the week — and the people who compensated best were the ones who lost or maintained weight long term.1
So don't judge by a single weigh-in: weigh yourself every morning under the same conditions, look at the weekly average and compare two-week averages. Waist circumference is a good second measure.
The 7 most common reasons
Ordered roughly from most to least common in practice.
- Eating more than you log: In a classic study of people who described themselves as "diet-resistant," participants under-reported what they ate by 47% and over-reported their activity by 51% on average — while their metabolism was normal.2 It isn't deliberate; tastes, sauces and oil are easy to forget.
- Drinks and snacks: Coffee add-ons, juice, soda and grab-and-go snacks are the calories that most often slip out of a log.
- The weekend effect: A weekday deficit can be wiped out by two days of surplus; the weekly total is what counts.
- Overcounting exercise calories: In a study testing wrist-worn devices, none achieved an energy-expenditure error below 20%.3 Eating back everything you "burned" can close your deficit.
- Your needs fall as you lose weight: A smaller body burns less energy; weight responds slowly to a change in intake, with a half-time of about a year.4 The target that created a deficit at the start may not after 5–10 kg.
- Sleep and stress: In a sleep-restriction experiment, the fullness hormone leptin fell by 18%, the hunger hormone ghrelin rose by 28% and hunger increased by 24%.5
- Muscle gain and water retention: Starting strength training can make muscles hold water in the first weeks; the scale stalls while your waist shrinks.
A 4-week checklist
Before blaming your metabolism, try this for four weeks:
- Log everything for two weeks, including drinks and weekends.
- Weigh yourself every morning after the bathroom, in the same clothes; note the weekly average.
- Measure your waist once a week.
- Recalculate your calorie target for your current weight.
- Eat back at most half of your exercise calories.
- Aim for a portion of protein at every meal and 7 hours of sleep a night.
The NHS puts average needs at about 2,000 kcal a day for women and 2,500 for men, and notes that yours depend on your age, weight, height and how much exercise you do.6 A friend's target isn't yours.
Where to track this in Suu
Most of the checklist lives on one screen in the app. Menu names are exactly as they appear:
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See your whole day on one screen
Nutrition screen → Today
Your calories for the day sit next to your target, with meals listed by time; forgotten snacks become visible here.
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Log your drinks too
The Suui assistant on the home screen
Just say "I had a latte and two sweet teas"; the drinks' calories are added to the day's total. The free plan includes 3 AI messages a day; one-tap logging from the drink list is Premium.
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Spot the weekend effect
Nutrition screen → Last 7 days (calories)
See Saturday–Sunday spikes next to the rest of the week, so it's clear where your deficit disappears.
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Count workout calories realistically
Home → quick add → Add Exercise
GPS workouts show an estimate of calories burned; when working out your deficit, count half of it, not all.
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Nutrition Score
The Nutrition Score (1–100) in every meal analysis
Rates a meal's quality alongside its calories, making it easier to spot the meals that leave you hungry fast.
The short version
When the scale stalls, the first suspect isn't your metabolism but the measurement: look at weekly averages, log everything — drinks and weekends included — for two weeks, count exercise calories cautiously and update your target for your current weight.
If nothing changes after four weeks of a verified deficit, it's time to stop guessing and talk to a doctor or registered dietitian.
See your whole day on one screen
Meals, drinks and workouts in one place · free on iOS and Android
Frequently asked questions
I'm in a calorie deficit — why am I not losing weight?
The most common reasons are eating more than you log (drinks, snacks, weekends) and overcounting exercise calories. Water swings on the scale and energy needs that fall as you lose weight also cause plateaus. Look at the 3–4 week average before deciding anything.
How long does a weight-loss plateau last?
Plateaus that are really just daily fluctuation usually resolve within 1–2 weeks. If a stall lasts longer than four weeks while everything is logged accurately, recalculate your target for your current weight; if it continues, talk to a doctor.
Does eating more on weekends affect weight loss?
Yes. In one study weight rose over the weekend and fell during the week. A weekday deficit can be erased by two days of surplus; what matters is the weekly total.
I'm exercising but not losing weight — why?
Smartwatches and fitness bands easily overestimate calories burned; in one study no device got its error below 20%. Exercise can also raise appetite, and new muscle can hold water. Measure your waist as well as your weight.
Has my metabolism slowed down?
It's normal for energy needs to fall as you lose weight; a smaller body burns less. But in a classic study, people who called themselves 'diet-resistant' had normal metabolisms — the gap was in their logs. See a doctor if you have thyroid symptoms.
How does Suu help with a weight-loss plateau?
The Nutrition screen shows meals and drinks by time and the last 7 days of calories as a chart; GPS workouts show calories burned separately. So instead of guessing where your deficit closes, you can see it.
References
- Orsama AL et al. — Weight rhythms: weight increases during weekends and decreases during weekdays. Obes Facts, 2014
- Lichtman SW et al. — Discrepancy between self-reported and actual caloric intake and exercise in obese subjects. N Engl J Med, 1992
- Shcherbina A et al. — Accuracy in wrist-worn, sensor-based measurements of heart rate and energy expenditure in a diverse cohort. J Pers Med, 2017
- Hall KD et al. — Quantification of the effect of energy imbalance on bodyweight. Lancet, 2011
- Spiegel K et al. — Sleep curtailment in healthy young men is associated with decreased leptin levels, elevated ghrelin levels, and increased hunger and appetite. Ann Intern Med, 2004
- NHS — Understanding calories
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Suu is not intended for medical diagnosis or treatment. Consult a healthcare professional for health-related decisions.