What fraction of loss on orforglipron is lean mass according to TRIUMPH-3?

Setup, so nobody has to ask: orforglipron · TRIUMPH-3.

I have read the primary source rather than the summary, which has left me with more questions.

I understand the headline. I do not understand the footnotes, and the footnotes look important.

What would I need in addition before this supported a decision?

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.

Absolute strength holds up better than scale weight during a deficit for a straightforward reason: strength is substantially neural and skill-based, and the contractile tissue you retain is being trained harder relative to its size. Grip strength and repetition maxima are therefore lagging indicators of muscle loss rather than leading ones, which is an argument for measuring both.

Food noise returning is not obviously tolerance. Receptor desensitisation is one hypothesis; a second is that the initial effect was partly novelty and partly the steep early deficit, and a third is that intake has drifted upward and the signal is being outcompeted rather than weakened. The three make different predictions about what a dose increase would do.

The STEP 1 extension reported substantial regain in the year after treatment withdrawal, with weight and cardiometabolic variables trending back toward baseline[1].

I would be careful with the supplement literature here; effect sizes are small, the studies are mostly in trained young men, and generalisation to a large deficit is not obviously valid.

Measure strength as well as mass. It is cheaper, it is less noisy, and it is closer to what you actually care about.

What the data supports is narrower than what gets recommended, so it is worth separating the two.

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.

Put another way, fibre at very low total intake is a trap. Soluble fibre needs water and motility to work; insoluble fibre adds bulk to a slow transit. At 900 kcal a day with delayed gastric emptying, an osmotic agent is more predictable than a bulking one, and adequate fluid is doing more work than either.

SURMOUNT-4 provides the cleanest maintenance-versus-withdrawal contrast available in the class, and it is the reference for any claim about what happens after stopping[1].

The caveat is that population averages tell you about populations. Your own trajectory is a sample of one and should be read as a trend, not as a deviation from a published mean.

Two resistance sessions a week and a protein target you actually hit will do more than any refinement beyond them.

edited 11 May 2026 by w_okoye — removed a claim I could not source

Specifically, the mechanism is worth having straight, because it predicts which interventions can work and which cannot.

The regain trajectory after stopping is roughly a mirror of the loss trajectory, and it is not primarily a willpower phenomenon. Appetite signalling returns, energy expenditure remains suppressed relative to the original mass, and the two combine. That is an argument for a maintenance plan existing before the stop, rather than an argument against stopping.

The body-composition substudies in the major programmes consistently report that the proportion of weight lost as fat mass is approximately three quarters or better, with the lean-mass fraction falling within the range seen in dietary weight loss of comparable magnitude[1].

A maintenance plan written before you need it is worth more than a better loss plan.

edited 13 Mar 2026 by bufferline42 — updated for the 2026 guidance change

To be exact about it, the distinction that resolves this is between proportional loss and functional loss. Losing lean mass in proportion to total mass is what happens in every weight loss intervention. Losing function is not, and function is measurable.

Hydration state moves a DEXA lean-mass figure directly, because the algorithm assigns water to the lean compartment. Scanning fasted, at the same time of day, before training and without a recent high-carbohydrate day is the difference between a comparable sequence and a noisy one. Bioelectrical impedance is far more sensitive to hydration again, which is why its trend is unusable at this timescale.

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.