Food diary
A food diary is a record of everything eaten over a period, kept on paper or in an app; its value comes from consistency and honesty rather than from the precision of any single entry.
A food diary does two things at once, and people usually only notice the first. It produces a calorie total. It also makes you aware of what you are eating at the moment you eat it, which changes behaviour on its own — the effect shows up even when nobody adds anything up.
What makes one useful
Completeness matters more than accuracy. A diary missing the oil, the chai sugar and the two biscuits at four o'clock is not a slightly imperfect record; it is wrong by several hundred calories, which is the entire size of a typical deficit.
Timeliness matters nearly as much. Logging at the meal is reliable; reconstructing the day at bedtime is a memory test, and memory reliably forgets in one direction.
What it is not
It is not a report card and it is not a confession. A day logged honestly at 3,000 kcal is more useful than a day logged flatteringly at 1,800, because only one of them can be acted on.
When to stop
Most people do not need to log forever. A few months builds an internal sense of what portions cost, after which many switch to logging only during a deliberate fat loss phase, or only the meals they find hardest to judge.
Sources
- 1.Weight management — NIDDK, National Institutes of Health
- 2.Dietary Guidelines for Americans, 2020–2025 — USDA and HHS
Related reading
- Calorie tracking for beginners: your first seven days
A day-by-day start that does not require perfection: what to log on day one, what to add each day after, and what to ignore entirely for the first week.
- Paper food diary or app: which one you'll keep
Paper is faster to start, private by default and hopeless at arithmetic. An app does the sums and adds friction. Which failure mode matters more to you.
- How to track calories without giving up in week two
A method for counting calories that survives home cooking, restaurants and a normal week, using the accuracy you need rather than what apps pretend to offer.
- Why two apps give the same roti different calories
Different databases, source types, raw versus cooked states and user-submitted entries. Why calorie apps disagree, and which number you should actually use.