Kitson, 27, is furious Royals chased cash by playing a pre-season tournament in South Korea.
The striker insists they should have focused on reproducing last season's eighth-place finish - rather than grabbing the money on offer in Asia.
He said: "Going to Korea meant we didn't do a proper pre-season. We went there to make the club money and shouldn't have. We were not as fit as we should have been for the first few weeks.
"Yes, we played a few games - but we couldn't do anything in between. It was so hot. You couldn't play a game and then do high-intensity running as you would just die. I lost a stone in one game against River Plate. We were absolutely passed to death and I was running around like a madman.
"If you are losing a stone in one game, how can you say afterwards you have had a proper pre-season?
"We were already behind everyone else."