For people on semaglutide, tirzepatide and other GLP-1s
Lose the fat.Keep the muscle.
An iPhone app for people on GLP-1 medication. Every day it tells you how much protein to eat and gives you a short strength workout, matched to where you are in your dose week — so you lose fat, not muscle.
How it works
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Tell it your medication and dose day
Semaglutide, tirzepatide or another GLP-1, and the day you take it. Add your weight. That’s the whole setup.
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Each morning, get your day
How much protein to eat, split into small portions you can manage with no appetite — and a 15–25 minute strength workout for home or the gym. Lighter the days after your shot, harder when you feel strong.
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See that you’re losing fat, not muscle
Log what you lift and your weight, or sync weight from Apple Health. Holdfast shows your strength next to the scale, so you know the kilos going are fat and not muscle.
Your week, planned around your shot
Nausea and fatigue tend to peak a day or two after a dose. Holdfast goes easy then and asks more of you when you’re strong.
An example week for a Monday dose. Each morning you can also say how you feel, and the day’s workout adjusts.
Not all of the weight you lose is fat
In clinical trials of GLP-1 medications, between about 15% and 60% of the weight people lost was lean mass, depending on the study. Lean mass isn’t only muscle — it also includes water, organs and bone — and researchers still debate how much the loss matters for strength.
What isn’t debated: enough protein and regular strength training help protect muscle while you lose weight. Both get hard when appetite and energy drop. Holdfast makes them doable anyway.
Source: “Changes in lean body mass with glucagon-like peptide-1-based therapies and mitigation strategies”, Diabetes, Obesity and Metabolism, 2024. PubMed 38937282
Be first to try Holdfast
In development for iPhone. Early-list members get it first and help decide what it does.