Will I lose muscle on an extended fast? Separating Fact from Fear
                                
                                
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                                    4 min read                                
                            
                                Studies indicate that the body preferentially burns fat for fuel during prolonged periods without food, rather than indiscriminately breaking down muscle tissue. This metabolic switch to ketosis is the primary mechanism that prevents significant muscle loss on an extended fast, but the process is more nuanced than simple fat-burning.