Would it be bad for my gluttonous dog  if I keep him eat until he couldn't eat anymore just once?

He may go into bloat if you do that.  Twisting intestines & forming a complete block.  Dog would die without a Vets help.

(c/p)Bloat From Overfeeding

This puts pressure on other organs and can cause the dog to have difficulty breathing, restrict blood flow to his heart, and cause tears in his stomach lining. This condition is potentially life threatening, so see your vet immediately if you notice the following symptoms: A swollen stomach.

What Happens When A Dog Eats Too Much? - Rehome by Adopt-a-Pet.comhttps://rehome.adoptapet.com/ › answers › dog-rehoming

Only bad for the dog = as it could lead to its death.  Do look up Bloat, Torsion & volvulus in dogs.

https://www.petmd.com/dog/conditions/digestive/c_d...

https://pets.webmd.com/dogs/gastric-volvulus-bloat...

http://www.thedogplace.org/HEALTH/bloat-gastric-to...

James, your questions are seriously disturbing.  Anyway, could you post this in English?

Yes, it could. It has the potential to kill him.

No dogs love to eat.