Without resistance training and adequate protein, research suggests that roughly 20–40% of total weight lost during a calorie deficit can come from lean muscle rather than fat. With muscle-protective habits in place, that proportion drops substantially. This tool gives you an illustrative range for a planned weight loss — it is not a prediction, but it makes the stakes concrete.
Muscle-loss estimator
Frequently asked questions
How much muscle will I lose on a GLP-1?
Without resistance training and adequate protein, roughly 20–40% of total weight lost can come from lean muscle. With muscle-protective habits (protein 1.2–1.6g/kg and regular resistance training), that proportion can be substantially reduced. These are illustrative ranges — individual results vary.
Can I prevent all muscle loss on a GLP-1?
Complete prevention is unrealistic during significant calorie restriction, but the muscle-loss proportion can be substantially reduced with resistance training 2–3 times a week and hitting a protein target of 1.2–1.6g per kilogram of bodyweight.