Well, what did Apostle Paul teach in 1 Corinthians 10 which goes with that idea? Our Lord Jesus was speaking to His disciples He sent to preach The Gospel, so that is one factor in that which should not be missed.
1 Cor 10:25-31
25 Whatsoever is sold in the shambles, that eat, asking no question for conscience sake:
26 For the earth is the Lord's, and the fulness thereof.
27 If any of them that believe not bid you to a feast, and ye be disposed to go; whatsoever is set before you, eat, asking no question for conscience sake.
28 But if any man say unto you, This is offered in sacrifice unto idols, eat not for his sake that shewed it, and for conscience sake: for the earth is the Lord's, and the fulness thereof:
29 Conscience, I say, not thine own, but of the other: for why is my liberty judged of another man's conscience?
30 For if I by grace be a partaker, why am I evil spoken of for that for which I give thanks?
31 Whether therefore ye eat, or drink, or whatsoever ye do, do all to the glory of God.
KJV
If I were marooned on a desert isle with nothing but shellfish to eat, I'm going to eat to live, and give thanks for it. But when I get back to civilization, I'm not going to continue in that, because I know (and medical science agrees) that shellfish is very... high in cholesterol, which is bad for the body because it clogs up the arteries.
And if I go to a foreign country with The Gospel, and they set a plate of opossum on the table, I will give thanks and eat, not wanting to offend them for The Gospel's sake. But I won't continue in that food apart from them, for I know it is not healthy for one's body.
But what some brethren who go against the idea of eating healthy do, is to think that as long as they give God thanks for whatever they eat, that He will somehow cleanse it of the unhealthy chemicals in it, making it healthy to eat.
But if that's what people want, then I'm not going to judge them for it. Nor will I be judged for what I choose to eat, or choose to not eat.
Even when God showed Apostle Peter the vision of a blanket of unclean animals, (which was actually about His Salvation going to Gentiles, and not a declaration to eat unclean food at all), Peter showed that he had never eaten any of those things in his whole life.
I lived in Europe for three and a half years, and where I was the majority of people ate healthier than we do in the U.S. because their food system was setup better. They didn't eat a lot of frozen foods, McDonalds and such, and I don't recall ever seeing a freezer in their homes like we do. Even in small villages they would go to the local market daily to prepare their food fresh each day. They only had one type of salad dressing, olive oil and vinegar (which is very healthy), and only leafy type lettuce (again very healthy). Their whole system of fresh produce, fresh butchered meats, and even fresh daily baked breads from stone ground wheat the old world way was a daily fare. And the food was cheap, the cheapest restaurants were of the quality of one our more expensive ones in the U.S. in a major city.
