Nowadays, we can head to the bench and load up the plates. I'm curious as to the methods spartans/other ancient warriors in general used to gain weight/muscle. Did it come through fighting/sparring? Did they lift makeshift weights and throw discuses? Sorry if this is an ignorant question, but I am curious about this.
I answered this question in detail here. The short of it is that the training of Greek warriors, insofar as it existed at all, wasn't focused on gaining weight. Muscle mass was a burden; military service required stamina, agility, and the ability to put up with possible shortages of food, water and sleep. The ideal was not to be large and strong, but to be in shape and healthy so your body could easily bear the strain.
We have no evidence that Spartans sparred or trained with weapons, lifted weights, or did strength exercises. Their training was in athletics and team sports.