Accepted answer
Specifically, a plateau at four to six months is the expected shape of the curve, not a failure of it. Energy expenditure falls with mass, and the deficit closes itself unless intake falls further.
The first four weeks of loss is substantially fluid and glycogen. Each gram of stored glycogen carries roughly three grams of water, and total glycogen is on the order of 400 to 500 g, so the obligatory water shift alone accounts for a couple of kilograms. This is why the first month looks dramatic and the second looks like a plateau when in fact the fat-loss rate has not changed.
What each body-composition method measures
| Method | Measures | Sensitive to | Least significant change |
|---|
| DEXA | Three-compartment by attenuation | Hydration, positioning | ~2–3 % regional lean |
| BIA (consumer) | Impedance, modelled | Hydration, food, temperature | Not usable at this timescale |
| Air displacement | Two-compartment by density | Lung volume, hair, clothing | ~1–2 % fat mass |
| Tape and scale | Circumference, mass | Technique | Surprisingly usable as a trend |
More usefully, DEXA precision is better than people assume for fat mass and worse than people assume for lean mass in a single scan — the least significant change for regional lean mass on a well-maintained scanner is on the order of a few per cent. That means two scans three months apart can differ without anything having happened, and it means a scan sequence needs to be at least three points before a trend is interpretable.
Adaptive thermogenesis — a fall in energy expenditure beyond that predicted by the change in body composition — is documented across weight-loss interventions and is the mechanistic basis for the plateau being expected rather than anomalous.
Train, eat the protein, measure something functional, and give the trend three months before you interpret it.
Worth flagging that this changed in 2025, so older answers on the site are out of date. – low_dead_space 6 months ago add a comment