The Mental Health Score That Did Not Move

SURMOUNT-5 is the head-to-head trial, and its quality-of-life analysis found what you would expect on the physical side: people felt better in their bodies, more so the more weight they lost. On the mental side it found something else. The Mental Component Summary did not significantly improve in either treatment arm over 72 weeks.^[1]

What was measured

Participants completed the SF-36 version 2 — a widely used health survey that produces a Physical Component Summary, a Mental Component Summary, and eight separate domain scores — along with the PHQ-9 depression questionnaire and a global impression of physical activity, at week 72. Scores are norm-based, meaning the general population averages 50 with a standard deviation of 10, which makes the numbers comparable across studies.

One design choice shapes everything below: this was an on-treatment analysis, restricted to people who received the drug at their maximum tolerated dose. Anyone who could not stay on either medication is not in it. That inflates both arms equally and is worth remembering before reading any of these as what a randomly chosen person would experience.

The physical side

Physical function, bodily pain, role limitations and vitality all improved, and improved more in people who lost more weight. That is a coherent, unsurprising and welcome picture: carrying less weight makes moving through a day easier, and the survey detected it.

The one head-to-head difference was in General Health, where tirzepatide gained 5.45 points against semaglutide’s 4.20. That difference is real — p = 0.003 — and it is 1.25 points on a scale whose standard deviation is 10, roughly an eighth of a standard deviation. Statistically dependable, clinically modest, and those two things are not the same claim.

The result the conclusion does not mention

The paper’s own conclusion opens by saying health-related quality of life improved with both drugs. That is true of the physical measures and it is not true of the mental summary, which the conclusion does not mention.

Seventy-two weeks, the two most effective weight-loss drugs available, and mental wellbeing scores did not move.

★ Since we published this, a network meta-analysis of 43 trials and 45,663 participants reached the same conclusion across the whole drug class: no agent improved quality of life beyond the threshold agreed in advance as noticeable to patients — what 262 trials say together. One trial finding this is easy to dismiss. Forty-three finding it is not.

This matters because of what people are told to expect. Weight loss is routinely sold as a route to feeling better about yourself, and a great deal of marketing in this category trades on exactly that promise. The best-controlled evidence available — a randomized head-to-head with a validated instrument — found large weight loss improving how people’s bodies functioned without a measurable improvement in the mental component.

What to take from it

• Expect physical improvement, and expect more of it if you lose more. That relationship held across both drugs.
• Do not plan on the drug fixing how you feel about yourself. If that is the main reason for starting, this is the evidence to weigh.
• The head-to-head difference is small. An eighth of a standard deviation on one domain is not a reason to choose between two drugs; tolerability, cost and supply are larger considerations.
• It is an on-treatment analysis. The people who stopped are absent from both arms.

For the weight results these scores sit on top of, see the tirzepatide timeline; for what these drugs do to motivation specifically, semaglutide and motivation.