Reading your progress

Why am I not losing weight when I count calories?

It is the most common question from people who log their food. The answer is almost never a 'broken metabolism'. Usually it is a mix of small logging errors and the fact that the scale is misleading from week to week.

Updated 26 October 2026 · 7 min read

In short

On average, people log less than they eat – especially fats, drinks and bites.
Watch calories tend to be too high; photo estimates tend to be too low.
Water can hide fat loss for weeks – look at the trend over 4+ weeks.
A one-week 'audit' reveals most causes without changing your diet.

7 common reasons

1. Logged intake is lower than real intake

In a well-known study in the New England Journal of Medicine, people who said they could not lose weight on a low-calorie diet underreported their actual intake by 47 % on average. Nobody was lying – cooking fats, sauces, drinks and 'just a bite' simply slip through.

2. Photo estimates tend to be low

Preliminary results from researchers at the US National Institutes of Health showed that four popular photo-recognition apps underestimated both calories and fat by about a third. A photo is a good start, not a finished entry.

3. Watch calories are overestimated

In a Stanford University study, none of the seven wrist-worn devices tested estimated energy expenditure with an error below 20 %. If you 'add back' every calorie your watch shows, your deficit can easily disappear.

4. Water hides fat loss

Short-term weight changes are mostly water and other fat-free mass, not fat. Salt, carbohydrates, training or the menstrual cycle can mask fat loss for weeks – and then the scale drops 'all at once'.

5. Only good days get logged

If the weekend or a party is missing from the diary, the average looks better than reality. Many people are naturally heavier after the weekend – what matters is whether they balance it during the week.

6. Expecting linear loss

The body adapts when intake changes, so the same deficit does not produce the same loss every week. Slowing down after the first weeks is normal and does not mean the plan stopped working.

7. Too short a time frame

Two weeks is too little to judge with water swings. Comparing averages over 4 or more weeks gives a much more reliable picture.

The one-week audit

Before eating even less, try logging as precisely as you can for one week – without changing what you eat:

Log right after eating, including drinks, bites and the weekend.
Measure fats with a spoon – one tablespoon of oil is about 119 kcal.
Check photo estimates: portion, sauce, oil.
Keep expenditure simple – one reliable number or a profile estimate, nothing twice.
Weigh under the same conditions and compare weekly averages, not single days.

After a week, compare your logged intake with what you thought it was. Most people find at least one 'gap' – and fixing it is usually easier than cutting more food.

When to talk to a professional

If you have logged honestly for several months, the trend does not move and you have other symptoms (tiredness, cycle changes, new medication), talk to a doctor. Some health conditions and medicines affect weight and body water – a food diary cannot solve that.

Frequently asked questions

Why am I not losing weight when I eat few calories?

Most often because logged intake is lower than real intake (fats, drinks, bites), watch calories are overestimated, or water hides fat loss. A week of precise logging and comparing averages over 4+ weeks helps.

How long until I see results on the scale?

Single days and weeks are distorted by water. Comparing averages over 4 or more weeks is more reliable.

Should I eat even less?

First check that your log is complete. Fixing one gap in the diary is often easier than cutting intake further.

Sources

This guide is general information for healthy adults, not medical advice. If you are pregnant, breastfeeding, have or have had an eating disorder, or need a therapeutic diet, talk to a doctor or registered dietitian.