Is it possible that a guy does gym whole day every weekend?

I met a guy around 5 months ago. We never met in person as we are living in two different cities. He usually replies fast during weekdays. But every Saturday and Sunday, he disappears the whole day. It can be like we text in the morning then he will respond to me in the evening/late night before he sleeps. I questioned him dating someone but he denied. Basically every weekend is like this. He said all he did was just going to the gym. Can a guy do gym for the whole day on both Saturday and Sunday?
Is it possible that a guy does gym whole day every weekend?
Post Opinion