Times have certainly changed. For the most part the guys in our boot camp (1968) came out less fit than when they went in. It was the navy.
Still true in some cases. I lost 7 lbs and didn’t really need to when I went through 20 years ago. For the most part, however, it helped the majority of others in with me. They waited until the final two weeks to measure us for our class A uniforms for a good reason.