I think several different discussions are kind of getting mixed up (which is fine, but can be confusing).
One is the question of the morality of food. On that point, the Bible is quite clear. Every creature of God is good and nothing to be refused, if it be received with thanksgiving. We are to be grateful for what God gives us, and enjoy good food, while not eating for drunkenness. God gives bread, and wine, and oil; and animals and herbs and fruit. We must be firm on this point against those who would attempt to make us feel guilty for eating.
Again, the Bible is quite clear that there is no salvation through nutrition. Meats for the belly, and the belly for meats, but God shall destroy both it and them. We can enjoy God's goodness through a grateful use of good food, but eating and drinking are not and never can be the kingdom of God. We must be firm on this point against those who would attempt to make a religion out of diet (or health or longevity: I am not commanded to live long, or to be well, but to be faithful with what I have: a subtle shift of emphasis that may quite radically change the approach).
The Bible is also clear that for some people their god is their belly, and man does not live by bread alone, and so we are called to discipline, to self-restraint in the matter of food, as in the matter of any other appetite. It doesn't make food bad; but it's no surprise that we are capable of abusing this gift as well.
That's one discussion, but I don't think there's much disagreement there: we just have to remember these things and try to keep them as fundamental in all our thinking about diet, and diet recommendations.
Then there is the question of what foods are healthy and what foods are unhealthy. That's a separate issue, and on that score, what is good for some people may not be good for others (allergies are an easy example: peanuts are, in fact, very bad for some people). Now there are hundreds of diets out there, all claiming to be effective for their particular purpose, whether it be weight loss or building muscle mass or improving your health or increasing your longevity or mental agility, or whatever. Here, it's obvious that we can't dictate to one another; that the field is broader than what can be studied, but that the studies probably exceed the grasp of most individuals, and that common sense is your best friend. Some of the diets are dangerous, some are stupid, some are unpalatable, and some are simple variations on a theme: but good and bad diets are marketed aggressively and deceptively, with appeals to self-righteousness and self-indulgence of every form. The thing I would be concerned about here would be making recommendations that, though perhaps intrinsically pretty decent are completely inapplicable to the case of the person receiving the recommendation (see Vic's example above), or through reductive thinking coming to embrace a diet that can be positively dangerous. Take as an example the addition of fiber to yogurt. That fiber is vital for the proper functioning of the human organism, I take it, is not really a controvertible proposition. That the "fiber" in yogurt does any good has yet to be proven. Isolating a nutrient from its proper context, whether as a supplement or through processing or by making it the dominant factor in a diet, seems unlikely to obtain good results. In the same way, isolating diet from exercise habits, sleep patterns, stress levels, etc., is also unhelpful. I take it that all this complexity basically means that we are all reduced to the level of listening to anecdotes and learning by our own experiments what works for us, unless we are in the position to hire a personal consultant to design a lifestyle for our own health - and if that's our case, we probably need to add a personal chaplain to remind us that we will return to dust and that the fashion of this world perishes.
Another issue is the use of the Bible with regard to diets. Obviously there are people who abuse Scripture ("The Maker's Diet") in order to impose a system of eating that binds the conscience. I haven't seen that on the thread. But inasmuch as the Bible gives reliable historical evidence, it is certainly fair to point out, for instance, that Isaac, who lived far longer than any of us will (and lived longer than his father or his son) was very fond of eating wild game. The Bible does take it for granted that grain will be a fundamental part of the diet: that doesn't make it a prescription, but it does mean that any recommendation to eat primarily vegetables is unhistorical and consequently to be received with quite a fair degree of skepticism. It may be true, as Huxley has suggested, that the ideas of the Biblical people's about what constituted an exciting feast may have been conditioned by the difficulty of acquiring much in the way of fats in their diet; but since they wrote down those things under divine inspiration it seems a reasonable conclusion that meat and bread, butter and cheese and honey are (by and large) objectively good.
These discussions always get around to the matter of general health, and comparisons with the past. Well, the only golden past that can really be demonstrated is too far away for us to ever return. And I am always skeptical of statistics in this matter. Because rising "levels" of some disease are merely rising levels of reports of a given disease. And people often mistake the meaning of the statistics. Just last month I ran across two separate authors who thought that if average life expectancy was lower in the past that must have meant it was very unusual for anyone to pass 40. But that is nonsense: if 50% of babies die before they are one, and the average life expetancy is 40, then a lot of people were living well beyond that point.
In summary, don't expect that other people's experience will mirror your own; don't buy marketing campaigns disguised as science, or science that neglects common sense; and keep in mind that Scripture gives us liberty to enjoy food, while reminding us that it is ultimately a matter of very little moment.