eli5 Why is it, when eating healthy, junk food feels bad; and when eating bad, junk food feels normal?

Question

For example after a cleanse eating processed foods and sugars give headaches, whereas if those are common staples in the diet there’s less reaction. Same with dairy. It seems like a tolerance thing and on the surface makes sense, but what is actually happening?

In: 4

Answer 1

Your stomach has 3 strains of bacteria
1 responds to vegetables
2 responds to sugar
3 responds to meat
So if you eat a lot if vegetables then that strain is bigger and doesn’t like it when you eat the others or vice versa