Big effect
Whey protein after gastric bypass significantly slowed muscle loss — but didn't affect total weight loss in the first three months
This is the first controlled trial to show whey protein can selectively preserve lean mass after one-anastomosis gastric bypass, but the short duration and narrow patient group mean the finding needs replication before it applies broadly.
In a double-blind trial, people who took two scoops (about 22.6 g) of whey protein daily for three months after gastric bypass surgery lost less muscle and fat-free mass than those on placebo. However, the supplement did not change overall weight loss or nutritional markers. The benefit was limited to preserving lean tissue during rapid post-surgical weight loss, and the study only followed patients for three months.
Where this fits in the evidence
This is among the first studies we've indexed on Whey Protein for Reduced Lean Body Mass Loss — treat it as an early signal until more research accumulates.
The study
- Randomized Controlled Trial (RCT)
- 2025-10
- Clinical nutrition ESPEN
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