I am under the impression that body fat as energy storage is mainly meant to supplement eating during times when food is scarce. But if someone were to take vitamins to prevent scurvy and replace whatever essential amino acids that a body needs on a daily basis, could they just rely on body fat for their caloric needs? Is it absolutely critical that vitamins be taken with foods for transport? If this is possible, what kind of timeframe are we talking about?
Without food, you starve.
You can do anything for awhile. What do you suppose is going on when somebody goes on a hunger-strike to protest something? They’re living on their fat stores. For awhile.
Because those stores are finite, eventually they run out, or at least your body is unable to get any more value from those stores which remain. At which point you die of starvation.
If you’re thinking of it as a weight-loss method, don’t. When food intake stops, the body goes into an emergency copnservation mode which does 2 things: 1) tears hell out of most of your systems, likely creating some permanent damage, and 2) greatly reduces your calorie burn, thereby extending the life of your fat as long as possible. 2) also makes you stupid, listless, and depressed compared to normal.
All the quality weight loss advice out there says the key is significant vigorous exercise to increase calorie consumption, and a careful mild underfeeding, just enough to produce a daily deficit, but not enough to trigger the involuntary starvation reaction.
I think you alo need a daily intake of some amount of protein.
Well, the OP did mention replacing essential amino acids, which amounts to the same thing. And though they only mentioned vitamins for prevention of scurvy (which only required vitamin C), I think we can take this to actually mean a multi-vitamin-plus-minerals.
There are, btw, “essential fats” - that is, with a minimum amount required as intake on a regular basis because the body needs it and can’t manufacture it. But the amount needed is so small (a few grams?) that we get it automatically.
Oh, don’t get me wrong, I would never dream of trying this as a weight loss system, as it is, I’m kind of a scrawny boy who has trouble keeping the weight on. I was just in a nutrition class last semester and we talked about glucogenesis or whatever it’s called where the body can create glucose from fat, or maybe it was protein, now that I think about it…
I guess what I was wondering is if someone morbidly obese like you see on those terrible daytime tv shows was trapped in their home with only multivitamin, mineral, and amino acid supplements (let’s say their calorie count can be ignored) would they find this dead having consumed all of their body fat, or would they die before that for some reason? Is it absolutely critical to have food physically pass through yor GI tract?
and by no means am I trying to imply that the obese are completely at fault for their situation and should try to starve themselves, either.
As long as they drank sufficient amounts of water and ingested all the other nutrients (by tablets, gels, whatever), they will live. But why bother if you can’t eat food. If the obesity is that bad, a gastric operation is available, which is not a panacea, but a start to a new life of healthy eating.
We had some threads about this last year (How long could you live without eating and the like). I found one case pretty close to what you are describing, it was a very hefty person (I think 460 pounds) who went for over a year with no solid food (in a hospital, under medical supervision).
He was on a diet of coffee, tea, water, vitamins and apparently his own stored fat. I’m not sure how much milk and sugar was in the coffee and tea but the guy dropped a huge amount of weight during that year.
So to answer your followup question, you evidently don’t require solid food going through your intestines to survive.
Probably the biggest danger of living off of your stored body fat is negative nitrogen balance from lack of protein. Your body can make much of what it needs from fat, but fat does not contain the nitrogen needed to make amino acids. Furthermore, even with sufficient nitrogen, your body can only make the 11 non-essential amino acids. There are 6 amino acids that your body can’t make. Someone living off of body fat would be able to stay healthier with sufficient nitrogen (protein) intake.