How often should I weigh myself?

Most mornings, under the same conditions — after waking, after the bathroom, before eating or drinking. More weigh-ins make the trend more responsive and more reliable; the minimum for a usable maintenance calculation is eight in a fourteen-day window.

Why does my weight fluctuate so much?

Glycogen, sodium, food volume in the gut, hydration and hormonal cycling all move the scale independently of body composition. Four pounds of swing across two days on an unchanged body is normal, which is exactly why decisions get made against a smoothed trend rather than a reading.

What is trend weight?

An exponentially weighted moving average of your weigh-ins, with an alpha of 0.25 — so each new reading moves the trend a quarter of the way toward itself. It damps the daily noise while still responding to a real change within about a week.

Should I weigh myself after a long run?

Not for tracking. Post-session weight is dominated by fluid loss and can read several pounds low, which is a hydration measurement rather than a body composition one. Weigh in the morning under the same conditions instead.

Does creatine affect my weight tracking?

Yes, substantially. Creatine adds two to four pounds of intracellular water in the first weeks, which reads to an energy-balance calculation as several hundred calories a day of surplus you did not eat. Start it at the beginning of a block, not in the middle of a measurement window.

The Weight Screen: Trend, Not Scale

The formula

trend[i] = 0.25 * raw[i] + 0.75 * trend[i-1]

That is the whole thing. One line, and it is the single most useful transformation applied to any number in the app.

The alpha choice is a trade. Higher alpha responds faster and lets more noise through; lower alpha is smoother and lags further behind reality. At 0.25 a genuine step change is roughly 90% reflected in the trend after about eight readings — fast enough to catch a real shift within a week and slow enough that Sunday's dinner does not register.

Why both lines are on the chart

The chart shows the trend as a line and every raw weigh-in as a point scattered around it.

That is deliberate. The raw points are the argument for the trend: seeing a two-pound spread around a line that is moving 0.3 lb a week makes the case better than any explanation. It also stops the trend from looking like a measurement it is not — it is a filter over data, and the data should be visible.

What actually moves the scale

Cause	Typical magnitude	Timescale
Food volume in the gut	1–3 lb	Hours to a day
Sodium and hydration	1–3 lb	Hours to days
Glycogen (and its bound water)	2–4 lb	Days
Creatine loading	2–4 lb	1–3 weeks, then stable
Hormonal cycling	1–4 lb	Cyclical
Post-session fluid loss	1–4 lb	Hours
Actual fat or muscle change	0.25–0.5 lb/week	Weeks

Look at the last row against every row above it. The signal you are trying to detect is smaller than every source of noise on the list, and often by a factor of five or more. That asymmetry is the entire justification for smoothing.

Weigh-in conditions

Consistency matters more than any particular protocol:

Morning, after waking
After the bathroom
Before eating or drinking
Same scale, on the same surface

Most days. The minimum for a usable maintenance calculation is eight weigh-ins in a fourteen-day window, and more makes the trend both more responsive and more reliable.

Do not weigh after a session. Post-session weight is dominated by fluid loss and reads several pounds low — that is a hydration measurement, not a body composition one.

The two situations that will fool the arithmetic

Worth knowing in advance, because both look like results.

A refeed out of a deficit. Expect three to six pounds in two weeks, and none of it fat. Refilling muscle glycogen binds roughly three grams of water per gram of glycogen, and the digestive tract refilling adds another pound or two. This is the moment people most often conclude a correct plan is failing.

Starting creatine. Two to four pounds of intracellular water over the first weeks. To an energy-balance calculation that reads as a surplus you did not eat:

3 lb over 14 days = 3 * 3500 / 14 = 750 kcal/day of apparent surplus

Your measured maintenance comes out 750 calories too low, and everything downstream is wrong in the same direction for weeks. Start creatine at the beginning of a block, not the middle of a measurement window.

Why this feeds maintenance

Trend weight is the input to the maintenance calculation, and it has to be — the raw scale cannot support it.

weightChangeLb = trendWeight(today) - trendWeight(14 days ago)
energyBalance  = weightChangeLb * 3500 / 14
maintenance    = avgDailyIntake - energyBalance

A one-pound error in the weight delta becomes a 250 kcal/day error in the maintenance figure. Raw weight carries several pounds of noise, so a maintenance calculation on raw readings is not merely imprecise — it is unusable. The trend is what makes the arithmetic possible. The full method.

Reading it alongside the waist

The scale alone cannot distinguish "the surplus is working" from "the surplus is too big". Two measurements can:

Trend weight	Waist	Reading
Up	Flat	Working. Hold everything
Up	Up	Above the lean ceiling. Cut 100–150 kcal
Flat	Flat	Maintenance
Flat	Up	Recomposition going the wrong way. Act
Down	Down	Losing fat. Check strength is holding
Down	Flat	Losing something that is not fat. Check protein

Waist-to-height is a cheap, repeatable proxy for abdominal fat that needs no equipment and makes no assumptions. It is used for its trend rather than its absolute value. The measurements screen.

What the screen does not show

No body fat percentage. Measurement error on every consumer method — scales, calipers, photos — exceeds the change you are looking for over any reasonable window. Adding a noisy number to a clean pair makes the pair worse.

No projection. Nobody can honestly compute where your weight will be in twelve weeks, and a plausible-looking projection is worse than none.

No goal weight countdown. A number counting down to a target invites reacting to the noise it was designed to filter.

What to do next

Weigh in most mornings for two weeks under consistent conditions, then look at the spread of the raw points around the trend. That picture is the most convincing argument available for why you should never make a decision from a single reading.