Can you live off your fat until you're skinny?

There was a study done where a seriously obese man (450+ lbs) was given vitamins and water and carefully monitored for more than a year. After 1 year and 17 days he was discharged with a weight of 180 lbs.
The study: http://pmj.bmj.com/content/49/569/203.abstract (Full PDF available)
DO NOT ATTEMPT! His urine had to be monitored frequently to make sure that his liver and kidneys weren't shutting down from all the protein he passed as his body ate itself.

Fat is just hydrogen carbon and oxygen bound together. No nitrogen. It only stores SOME vitamins and minerals. One could certainly live a very long time if they didm' have to do a lot of moving about, but living isn't always living. ON would also have to self cannibalize in order to get nutrients and nitrogen that is stored in the muscle, and as previously mentioned this on an extreme level can be very dangerous. I'm sure various health markers would be decreased and general over all well being would suffer. considerably.

It's basically potential energy for the body. The body simply needs more than just energy.

Fat was only ever intended to carry you over from one meal to the next in an environment where the next meal was uncertain. We are still adapted to crave fat and sugar because they are high energy foods and our ancestors needed all the calories they could get to survive through the winter. The guy in the study was burning fat for energy, but needed to take vitamin supplements or he would have been severely malnourished. Some vitamins are fat soluble, but many are not and would not have been present had he lived on his fat stores alone.

Interesting topic - now if you could just sleep for the year and dream you were skinny too...

The VLCD stuff - a friend of mine did this. She lost loads of weight and looked great. Three years later - all the weight plus more back on and a gallstone operation - one of the known effects of VLCD that doesn't get explained.

Me - slower than a turtle tramping through peanut butter but getting there...

Define "skinny"? Your body will cannibalize muscle tissue to save its fat reserves. You can starve yourself down to almost a skeleton (assuming you could survive without the micronutrient input), and you will still have a pot-belly.

Fat was only ever intended to carry you over from one meal to the next in an environment where the next meal was uncertain. We are still adapted to crave fat and sugar because they are high energy foods and our ancestors needed all the calories they could get to survive through the winter. The guy in the study was burning fat for energy, but needed to take vitamin supplements or he would have been severely malnourished. Some vitamins are fat soluble, but many are not and would not have been present had he lived on his fat stores alone.

Stuartian- i think you are my fave person in MFP! so knowledgeable! LOVE IT

Okay now roll with me on this. I was just reading a little bit about how the body works and how our body stores fat basically to use later as energy. So couldn't that energy be used instead of actual food? Like theoretically since our bodies evolved to survive famine, all our fat would be a huge asset in keeping us alive right?

And I'm not asking for any scandalous reasons like starving myself and living off fat. I love food! Just asking out of curiosity. The science is interesting to me

you will be skeletal and at the point of death by the time your fat stores run out. If you're talking about eating nothing, after a short time, your body will burn skeletal muscle in preference to fat, because your chances of surviving the famine depend on you having fat stores. Muscle cells use a lot more energy than fat cells, so in a famine, not only are they a source of energy in themselves (i.e. your body metabolises them to use that energy to make up the deficit) they are also costly to maintain. So basically, in an extreme food shortage, your body will jettison your skeletal muscle while preserving your fat stores. By the time you get to the kind of body fat percentages people want to diet down to, if you have starved yourself that low, you'll have very little skeletal muscle left, and you'll look more like a skeleton than a fitness model. Note: the body burns fat as well as skeletal muscle in a severe food shortage, but what you want when dieting is for the body to *only* burn fat, and that is not what the human body does in a severe food shortage.

If someone's body burned up all their fat while preserving their muscles, they would be the first to die in a famine, hence why human bodies work like that, because any Homo erectuses (or other ancestral species) with a mutation that made their body burn fat and not muscle in a food shortage would have died the first time there was a food shortage. So their genes were not left in the population. We inherited the genes of the survivors.... those whose bodies used skeletal muscle for energy in a food shortage survived the famines, so we inherited their genes,

Humans evolved to be hunter-gatherers, surviving famines is a trick we have up our sleeves, but it's not what we evolved to do. Exercising then eating high protein foods = success at hunting = gaining muscle mass, because that will enable you to continue succeeding at hunting. if you want to lose fat as well, then you need to eat a high protein diet with a small calorie deficit while exercising, so your body gets the message that you're succeeding at hunting and it needs to keep the muscle you're using regularly, then as the deficit is small the body will mostly make that up with fat, although unused muscle may get burned as well, especially if you're already fairly lean. If you have a lot of fat to lose and you're new to weight training, you may be able to build muscle and lose fat at the same time... from an evolutionary point of view, this response is probably best explained in terms of needing to hunt to survive. So the advice from bodybuilders etc, i.e. to eat a high protein diet and do exercise that puts heavy loads on the muscles, while eating a very moderate deficit, is easily explained in evolutionary terms, in relation to the need to carry on hunting even though there's a mild food shortage because success at hunting is what's going to help you survive the food shortage.

in terms of doing lots of cardio in a food shortage... that puts less strain on the muscles so there's an evolutionary advantage to burning some of the muscle for energy, which is why excessive cardio + drastic undereating has the same effect on body composition as doing no exercise at all in a food shortage. Any muscle fibres that are not necessary for survival (hunting) are burned for energy, to keep the metabolism slow (loss of muscle cells = able to survive on fewer calories) and to preserve the fat stores as long as possible. If the only exercise necessary for survival (i.e. the only exercise you're doing) is cardio, that gives your body quite a lot of unused muscle fibres. and even with weight training, if the deficit is too big you'll still see a loss of muscle mass, as the body can only do so much with the energy provided to it. It can't create energy out of nothing, so again, it's back to doing exercise that works the muscles hard plus a small deficit, for fat loss without loss of lean muscle)

Fat is just hydrogen carbon and oxygen bound together. No nitrogen. It only stores SOME vitamins and minerals. One could certainly live a very long time if they didm' have to do a lot of moving about, but living isn't always living. ON would also have to self cannibalize in order to get nutrients and nitrogen that is stored in the muscle, and as previously mentioned this on an extreme level can be very dangerous. I'm sure various health markers would be decreased and general over all well being would suffer. considerably.

It's basically potential energy for the body. The body simply needs more than just energy.

Hey smarty pants. How do you know so much stuff about stuff? What do you read?

Your comment combined with the other users about the guy who let his body eat himself confused me a little as they are slightly contradictory. If your body wasn't solely meant to use fat directly as energy, then what's the overall purpose? Short term energy? Is that why when we get fat we don't just stop eating for a year and get skinny? I always wonder about those vlcd that have people eating like 500 cals a day and the nutrient deficiencies people must have on those. Your fat doesn't really have any of the stuff you would need on a daily basis does it? It seems to be the lowest form of basic energy

Fat is a short, medium to long term energy source for the body. Muscle uses free fatty acids circulating in the blood, to make glucose when insufficient quantities are available. What the fitness tutor wrote is mostly correct. There is a constant turnover of protein in your body (creation and breakdown) releasing nitrogen for use in the primary needs. However, some loss via urine always occurs so you will degrade non-fat tissues. The basic lack of necessary vitamins and minerals is likely to significantly impact things like bone remodeling, etc.

Plus at very low cals one risks some of the niceties of a VLCD - kidney stones, etc...
So while it is possible to lose weight by absolutely not eating, it isn't healthy.

If you are interested in learning about this here is one source - http://highered.mcgraw-hill.com/sites/0072507470/student_view0/chapter25/animation__energy_sources_for_prolonged_exercise.html

You can review all the chapters on that site and get a good overview of the anatomy and physiology.

As to the study of the guy who did a year long fast, it has been shown more than a few times (The article reports 5, I've read at least of 3 other reports) that this lead to death (from the starvation or other various complications).

Some of thing to note:
The guy and the year long fast - this was in the 1960's.
- also took electrolytes.
- pooped about every other month.
- had significant bone dimineralizaton and soft tissue losses
- took vitamins, sodium and yeast supplements throughout
- took potassium in the middle due to loss issues

He did maintain his weight loss.
There are other reported fasts in the 60s of about 9 months. Check that article for references.

Oh, here.

Death during therapeutic starvation - http://www.ncbi.nlm.nih.gov/pubmed/4173428

It's of interest to note that therapeutic starvation for obesity basically stops appearing in published medical research after the early 1970's (well, except for the the Russians and a smattering of German reports, articles usually not translated...) No significant research with more than a few subjects of long-term starvation therapy is avaiable, as far as I know.