Almost certainly There's an entire essay devoted to the subject of lembas in History of Middle-earth , imaginatively titled "Of Lembas"; in it, Tolkien writes: The Eldar say that they first received this food from the Valar in the beginning of their days in the Great Journey.
For it was made of a kind of corn which Yavanna brought forth in the fields of Aman, and some she sent to them by the hand of Oromë for their succour upon the long march.
[...]
Now this corn had in it the strong life of Aman, which it could impart to those who had the need and right to use the bread.
History of Middle-earth XII
The Peoples of Middle-earth Part 3:
"Teachings of Pengolod" Chapter XV: "Of Lembas" Although "magic" in the Tolkien Legendarium is a difficult thing to pin down, "the strong life of Aman" certainly sounds magical to me.
scifi.stackexchange.com/users/31051/Jason Baker
Lembas may seem like magic to us, but the elves would have seen it as simply natural.
Clarke's Third Law is Any sufficiently advanced technology is indistinguishable from magic.
Arthur C. Clarke Hazards of Prophecy:
The Failure of Imagination Elves don't use "technology" the way we do, but they use their advanced understanding of the natural world to create things that seem impossible (and therefore "magical") to us.
While staying in Lothlórien (where the Fellowship is given a supply of lembas), Sam has a conversation with Frodo and says: '
It’s wonderfully quiet here.
Nothing seems to be going on, and nobody seems to want it to.
If there’s any magic about, it’s right down deep, where I can’t lay my hands on it, in a manner of speaking.'
‘You can see and feel it everywhere,’ said Frodo.
‘
Well,’ said Sam, ‘you can’t see nobody working it.
No fireworks like poor old Gandalf used to show.
I wonder we don’t see nothing of the Lord and Lady in all these days.
I fancy now that she could do some wonderful things, if she had a mind.
I’d dearly love to see some Elf-magic, Mr. Frodo!’
The Fellowship of the Ring: The Mirror of Galadriel Galadriel joins them and takes them to a garden on the slopes of Caras Galadhon to show them the Mirror of Galdriel.
When Frodo is unsure about looking in it
Galadriel says: ‘And you?’
she said, turning to Sam. ‘
For this is what your folk would call magic, I believe; though I do not understand clearly what they mean; and they seem to use the same word of the deceits of the Enemy.
But this, if you will, is the magic of Galadriel.
Did you not say that you wished to see Elf-magic?’
The Fellowship of the Ring: The Mirror of Galadriel
It seems to me that the elves (or at least Galadriel) understand that we view their more advanced creations (lembas, the Mirror of Galadriel) as "magic", but do not consider them in that light themselves.
scifi.stackexchange.com/users/66402/Blackwood
Its virtues cannot be explained with science.
From Letter
#210 We are not exploring the Moon or any other more improbable region.
No analysis in any laboratory would discover chemical properties of lembas that made it superior to other cakes of wheat-meal.
JRR Tolkien's letter to Morton Grady Zimmerman
scifi.stackexchange.com/users/54571/Wiles
Aside from the mystical perspective in the other answers, we can try to think up what lembas would be made out of if humans would make something like it.
According to this site , an adult male who is active (like Aragorn marching) needs 3000 calories per day.
According to this site , fat has the highest calorie count per gram, that is 9 per gram.
I can't post any more links, but I read that fat is slightly lighter than water.
This means that, unless one lembas cake is bigger than about one-third of a liter, it cannot store enough calories for Tolkien's claim, leaving aside anything else you need.
I always imagined it as way smaller than that, though I don't know of a quote by Tolkien stating that.
I also didn't imagine lembas to be just globs of fat...
scifi.stackexchange.com/users/69499/Ayane
The general tone of Elven 'technology' in Tolkien is that any magical element is rather subtle and more to do with the way that their whole culture approaches craft and knowledge than a simple case of magic bread +2 healing bonus.
Clearly there are plenty of examples of modern sports nutrition and military rations which could be considered analogues of lembas
and it's certainly not beyond all reasonable credibility in its properties.
For example in the Seven Pillars of wisdom by T E Lawrence (of Arabia) there is an account of Arabs using breadcrumbs mixed with almonds, sugar and butter as a trail food.
In fact this sonds a lot like marzipan (maybe marche pain >
>> walking bread).
It's certainly credible that a handful of fat, ground nuts and carbohydrate could keep you going for a day at a push.
scifi.stackexchange.com/users/59259/Chris Johns
I always had the feeling that Lembas bread was magical and that's what helped it be so fulfilling; however I've recently started to think that it was most probably just highly nutritious, and I had probably associated it with magic since it was Elven-related.  Is there any evidence that Lembas bread is magical?
Is Lembas (Elven bread) magical?
scifi.stackexchange.com
<tolkiens-legendarium><magical-items><food>
scifi.stackexchange.com/questions/135674
scifi.stackexchange.com/users/21267/Möoz
There is evidence in Tolkein's writing that Lembas bread is ineed magical. However, it would be fair to say that, what might seem magical to us, would seem perfectly normal to elves. Lembas certainly has properties which we humans would describe as magical but for elves it was a natural product.
Lembas is almost certainly magical because, for example, it is made of a special elvish corn which has a property described as the "strong life of Aman". We might regard lembas as magical but for the elves it was something natural, as in the case of many elvish things. The powers of lembas cannot be identified scientifically. The magical element in elvish products like lembas is more subtle than most forms of magic and is more like a kind of craft.