Guts made his fourth defense in June, 1975, but he gradually realized that it was becoming harder and harder for him to maintain his weight in the Lightweight division. For his fifth defense in December, 1975, Guts had to lower his weight 19 kg from his natural weight, losing 10 kg in the month before the fight. Guts lost his title in May 1976 to Esteban De Jesús by 15 round decision. The fight took place in Puerto Rico, and the country paid $200,000 (a rather large investment in the time period for a lightweight title match) to have Guts fight in Puerto Rico, showing Guts' widespread popularity at the time.