Originally posted by Mr. Slippyfist
When? 😕Because... the last time we saw Galactus before he went into the coma, he had just ate the Elders and a star, and a couple planets (because he was almost completely drained of power from the Infinity Gems). He wanted to feed right after that. So Nova, and Surfer went off to find him a planet. When they came back, Galactus was on the floor in a coma because the Elders were f*cking his insides.
He woke up, and he started to fight I-B.
So, unless he fed in the F4 series or something... he was starved for that fight...
It starts in Silver Surfer #9, vol3. The Elders of the universe, possessing the Soul Gems, attempt to confront Galactus. We see Nova finding a planet full of life, returning to Galactus to find him standing on top of his world ship confronting the Elders. You also see a scan of 6 planets linked together with the Soul Gems and a sun in the middle, which the Elders use to try and drain Galactus of his energies. Silver Surfer flies up and tells Nova to destroy the planets, so she does so by making the sun go nova.
After the sun goes Nova it turns into a huge black hole and rips apart the machine that the Elders created to use the Soul Gems. Somehow when that happens, the energies from the 6 soul gems and the planets they were linked into reverse the flow and begin to fill Galactus full of energy. He literally says "filling me to capacity!"
What we learn later on is the infinite power that exists within the Soul Gems, so IMHO Galactus was actually being filled by the power of the gems themselves, since the energy he got from the planets was greater than what the planets would have had.
Later on he becomes basically ill after trying to consume the Elders of the Universe, until they are freed from Master Chaos and Lord Order. As soon as they are freed he gets up and is full of energy still from before. IMHO he briefly tapped into the energies contained within the 6 Soul Gems, but even if you don't buy that, bare minimum he basically ate 6 planets at the same time.