This has mostly arrived in the consensus of sports training. General advice is to have protein surplus in the 24 hours after training (if you train every day, l

This has mostly arrived in the consensus of sports training. General advice is to have protein surplus in the 24 hours after training (if you train every day, like an athlete, that means every day). Plus if you're training but want to lose at the same time, you need a caloric surplus for a while to have your muscle regenerate and grow, but it's totally possible to gain muscle and lose weight at the same time. But basically each calory that you're in deficit will make your muscles grow more slowly, so it's definitely harder than being on an overall surplus.