Eating less makes protein the thing most worth protecting, and that is why Loopa raises your protein target on a GLP-1 protocol. This page explains the reasoning and the numbers behind it.
The problem in one paragraph
When you lose weight, some of what you lose is fat and some is lean tissue. In the SURMOUNT-1 body-composition substudy, roughly 75% of the weight lost was fat mass and roughly 25% lean mass, and that split was similar for tirzepatide and for placebo (Look M et al., Diabetes, Obesity and Metabolism, 2025 · doi:10.1111/dom.16275).
Note what that says. The split is a feature of losing weight, not something the medicine does. Which is also why the response to it is about food and training rather than about the medication.
Why protein specifically
Protein intake and resistance training are the two levers with the best evidence behind them for holding on to lean mass while eating less.
For people training while in an energy deficit, current recommendations sit at 1.6 to 2.4 g of protein per kg of body weight per day (Hector AJ and Phillips SM, IJSNEM, 2018 · PMID 29182451).
There is a point beyond which more stops helping. A meta-analysis and meta-regression found no further training-induced gains in fat-free mass above a total intake of about 1.6 g/kg/day, with a wide confidence interval around that figure (Morton RW et al., British Journal of Sports Medicine, 2018 · doi:10.1136/bjsports-2017-097608).
For older adults, the PROT-AGE group recommends an average daily intake of at least 1.0 to 1.2 g/kg, and advises higher intakes for those who are exercising and otherwise active (Bauer J et al., JAMDA, 2013 · doi:10.1016/j.jamda.2013.05.021).
What Loopa actually does
On a GLP-1 protocol Loopa raises your protein goal to a default of 1.6 g per kg. That number is Morton's plateau, which is the best-supported place to put a default: enough to be worth aiming at, and not a figure invented for the app.
Two things about it worth knowing.
It only ever raises. Loopa composes your goals to the most protective setting across every protocol you run, and it can raise a number but never lower one you set.
You can change it, and Loopa will not suggest a value. The adjustable range is 1.2 to 6.0 g/kg. The default is the only number Loopa ever offers; what you set is stored as you typed it.
Loopa also switches on a fiber goal and a hydration goal with a GLP-1 protocol, for the reason on the side effects page.
Hitting it when you are not hungry
This is the real difficulty, and it is worth saying plainly: a higher protein target arrives at exactly the moment eating gets harder.
Loopa's protein-gap helper works from food you already eat. It looks at your recent meals first, then the catalog, and suggests portions to the quarter serving. It excludes anything on your never-eat list and anything your own logs associate with a symptom.
How Loopa helps
- See the gap: the Today dashboard shows protein against your target.
- Close it: Health › Protocols › Protein gap suggests foods you already eat.
- Keep the number honest: Health › Goals shows the target and where it came from, with the source.
Related
- Protecting muscle while losing weight
- High-protein eating
- GLP-1 medicines explained
- Macronutrients explained
Where this comes from
Everything on this page is drawn from peer-reviewed research and published recommendations, cited above. The full list is at loopahealth.app/sources. Loopa does not give medical advice. Protein targets are general nutrition information; if you have kidney disease or any condition affecting protein intake, your clinician's number is the one to use.
