I was wondering about famines. Would a very large person be able to live until their entire fat supply was gone, or would something else kill them before then? I know that women survive better because they have a larger percentage of body fat than men. What if you were carrying 80 or 90 extra pounds. Would you be able to live for several months after all your skinny friends had starved to death?
I’m counting on it.
ho - me too. I used to do the 500 calorie starvation “Lindora” diet when I was young. It would take 6 weeks to lose 25 pounds.
Nothing important to add, but I wanted to say that I was curious about this as well.
Impossible to answer without specific values for body mass, activity level, diet during the famine, water availability, and a host of other things. It’s certainly possible that in a famine with little or no food available, scurvy (vitamin C deficiency resulting in lack of collagen) would take its toll on a certain number of individuals before their bodies exhausted their store of calories. Same potentially for other nutrient deficiencies. I would expect that someone less than 100 pounds overweight, who was burning a certain number of extra calories in a fruitless (hah!) search for food, would probably run out of fat before their connective tissues deteriorated completely. The body’s stores of vitamin C typically last approximately 2-3 months (http://whqlibdoc.who.int/hq/1999/WHO_NHD_99.11.pdf, page 13), and since it’s water-soluble and not fat-soluble, you have to replace it. Many of the types of foods available in famine areas are poor sources of vitamin C, if they supply any at all.
There’s also the potential for beriberi (thiamine deficiency), pellagra (niacin deficiency), and others, though most take long enough to kill that even the most obese individual would likely starve before that – they mainly take their toll on those who have some food, but food that’s deficient in these nutrients.
This source has some interesting and relevant information, especially Table 2 and the final paragraph of the page – there are apparently records of profoundly obese individuals who fasted for periods of between 7 and 24 months, each losing over 65% of their body weight. These are all, however, from the period after WWII, by which time the connection between vitamin C and scurvy had been well established, so I would imagine that these individuals all received some type of supplemental vitamin C (as well as other supplements).
FWIW, the Wikipedia article on famine response indicates that the brain’s requirement for a minimum of 10g of glucose per day will, within 40-50 days, cause sufficient protein loss (as proteins are broken down to create glucose) that critical organ function is no longer possible and death occurs from cardiac arrest, cardiac arrhythmia, or immune system failure, even in individuals that have not yet lost all of their body fat. If that is the case, the extended fasts reported in the article above must not have been “total” fasts as the article claims. However, 10g of glucose (approximately 1/4 of one 12 oz. can of soda’s worth) is enough to at least mitigate this effect, meaning that if there’s any food at all about, an obese individual might last long enough to exhaust their fat stores, assuming that scurvy, beriberi, pellagra, or other vitamin deficiencies didn’t do them in first.
That article does not cite any sources and honestly that sounds like complete nonsense to me. Please tell me that we didn’t spend millions of years evolving fat storage mechanisms only to have to cannibalize muscles and organ tissues even when extra body fat is available. If this is true, I want a damn refund.
I think it would be a reasonable default assumption (unless a reasonable cite states otherwise) that a person who would still be medically qualified as overweight or obese is not going to undergo organ failure due to lack of macronutrients. Lack of specific amino acids, fats or vitamins can perhaps kill you within 40-70 days, but you’re not going to start running out of energy until your fat level gets below what can sustain a sufficient metabolic rate. I don’t have a cite but I can’t envision our ancestors surviving bad winters and still being in a condition to hunt, gather, scavenge and otherwise feed themselves later on.
Not true. Here is a previous [thread=365432]thread[/thread] on this very topic.
Human beings are not evolved to exist naturally in a state of obesity, and fat deposits are evolved primarily as a means to store energy for endurance activities where the anaerobic metabolism takes over once glucose stores in the body are depleted; for instance, on a long walk or run, or to provide energy to maintain homothermic regulation of core body temperature. (Despite popular misconception, subcutaneous fat on humans provides little in the way of insulation; humans, having been evolved to live in the African equatorial and sub-equatorial savannahs, are not naturally well-suited to cold climes, necessitating the removal of insulated integument from other creatures by means of violence.)
In a “normal” diet you require an intake of a certain amount of carbohydrates along with proteins and fats–somewhere in the ratio of 50:30:20–in order to properly utilize incoming or deposited fat. The carbs provide the “fuel” to break down fats and synthesize or build required protein chains from the essentially proteins and fatty acids. You can synthesize glucose via gluconeogenesis from fatty deposits, but this is seriously inefficient, strains the liver and kidneys, and produces toxic byproducts that have to be excreted so that blood acid levels don’t rise to harmful levels. An obese person who isn’t taking in any carbohydrates or proteins will lose muscle mass and and suffer the toxic effects of ketosis. A long term lack of external glucose sources can result in diabetic ketoacidosis, where a lack of insulin production upsets the citric acid cycle and causes or exacerbates a number of deleterious effects, including muscle wastage, decalcification of bones, acidification of blood and tissues, et cetera.
And while most “micronutrients” (i.e. vitamins and minerals) are fat soluable, Vitamin C is not; the progression of scurvy is variable, but I’d guess that a couple of months without any source of Vitamin C would result in serious healthy effects. Even more concerning is potassium, sodium, and niacin balance: the first two are vital for neurological function and regulation of cellular membrane permiablility, and the latter for excretion of toxic products; all would be used much faster by a person in a starvation regime, and unless replenished could cause death long before fat reserves are used up.
High protein/low carbohydrate diets which have become popular in recent years were developed to treat people who are dangerously obese, because it essentially “burns off” fats without going through the normal gyrations of the citric acid cycle; however, they’re supposed to be closely regulated and monitored to maintain marginally safe insulin levels, and still often result in some harmful effects, but are less harmful than continued obesity. This should not be considered in any way a “normal” human diet, and indeed, even most informed promoters of these diets acknowledge that carbohydrate balance is important and emphasize the need for complex carbohydrates found in vegetables and pulses.
So no, an obese person couldn’t just simply live off of fat reseves and water. Given access to a moderate amount of carbohydrates, a source of Vitamin C, and proper hydration, however, they would probably live significantly longer than someone with minimal fat reserves.
Stranger
An interesting veterinary perspective-
Certain obese cats, when starvation occurs, will store some of the product of fat breakdown in their livers, resulting in a pathologic condition called hepatic lipidosis. Now, hepatic lipidosis causes (among other things) inappetance.
So, lets say you leave on vacation and leave plenty of food and water for the cat. For some reason (the wind blows a door shut) the cat no longer has access to the food for a few days. You return home, offer food, yet the cat still will not eat. By the time I see the cat, often the only way to reverse the situation is to place a feeding tube and force feed the cat.
The feeding tube typically needs to remain in place for 10 to 30 days, which can get expensive.
So, if you have a “fat cat” be careful forcing weight loss.
Umm ok. Note that I am not claiming we’ve evolved to be obese. I’m claiming that we’ve evolved a method of having some body fat regardless if it’s for short term or long term use.
True. I agree. Do you contend that once glucose stores in the body are depleted in the short term, your organ tissues are broken down simultaneously with the short term fat deposits to provide fuel, thereby causing some, if minor, organ damage? If not, then what mechanism do you propose for this switchover to occur when these reserves are being used for longer than necessary. Remember, we’re talking only about things like lung tissues being used for energy when fat stores are available, and I’m going to reputable need a cite before I believe that.
Cite? Scientists agree that 50:30:20 is definitely survivable and generally good enough. It is certainly not required within a scope of a few months or years, as proven by experience. You can always dig up studies showing that children who spent a long time on ketogenic diets for treatment of epilepsy or some such have a higher rate of kidney or heart disease, but then there’s just as many studies showing diabetes and obesity in children who didn’t. This question is still open, and no matter how much you want your 50:30:20 to be a scientific fact, wishing doesn’t make it so. Why not 10:40:50 or 25:35:40? Or hell, 5:30:65? Are you saying you can’t survive on those? Worse health?
That is grossly misleading. Ketoacidosis is a toxic effect of ketosis the same way hyperglycemia or diabetic coma are toxic effects of glycolysis. Ketosis is a normal metabolic process, and is not, in itself, dangerous or toxic, just different.
I would agree with the statement that an obese person couldn’t simply live off of fat reserves and water without access to certain micronutrients. They’d still, however, last a lot longer than a person in the same situation who was not obese to begin with. If you contend given access to water and micronutrients obese people will die of organ failure due to lack of macronutrients, or as you contend, just carbohydrates before their body fat drops below what is considered medically excessive, you’re going to need to prove it.
Give us our tools, and we’ll whup any other darned thing on this planet! 
I remember seeing a thing in News of the Weird recently about “Breatharians”, who, while claiming to be able to live solely on clear liquids and/or air, have famously been exposed primarily as frauds. I was thinking, “gosh, anybody who’s watched Survivor knows this can’t possibly be real! You need to eat at *least[/i ]one bowl of maggots per week to sustain yourself!
As an interesting aside, I thought I’d link in some good reading from The Master himself: Traditionally Eskimos ate only meat and fish. Why didn’t they get scurvy? For some reason, this subject seems to come up about once every three or four months.
Bottom line, skinny people taste bad (too stringy and tough) and will get hungry enough to consider cannabelism long before the fat ones realize whats up. :eek: