Metabolism Question- Starvation mode

Maybe everyone should be a little more understanding before automatically judging Julia when you don't know her history. Just sayin...

The body uses glucose as its main metabolic fuel if it is available. About 20% of the total energy consumption occurs in the brain. The rest of the glucose consumption fuels muscle tissue and red blood cells.
Glucose can be obtained directly from dietary sugars and carbohydrates. In the absence of dietary sugars and carbohydrates, it is obtained from the breakdown of glycogen. Glycogen is a readily-accessible storage form of glucose, stored in small quantities in the liver and muscles. The body's glycogen reserve can provide glucose for about 6 hours.
After the glycogen reserve is used up, glucose can be obtained from the breakdown of fats. Fats from adipose tissue are broken down into glycerol and free fatty acids. Glycerol can then be used by the liver as a substrate for gluconeogenesis, to produce glucose.
Fatty acids can be used directly as an energy source by most tissues in the body, except the brain, since fatty acids are unable to cross the blood-brain barrier. After the exhaustion of the glycogen reserve, and for the next 2-3 days, fatty acids are the principal metabolic fuel. At first, the brain continues to use glucose, because, if a non-brain tissue is using fatty acids as its metabolic fuel, the use of glucose in the same tissue is switched off. Thus, when fatty acids are being broken down for energy, all of the remaining glucose is made available for use by the brain.
However, the brain requires about 120 g of glucose per day (equivalent to the sugar in 3 cans of soda), and at this rate the brain will quickly use up the body's remaining carbohydrate stores. However, the body has a "backup plan," which involves molecules known as ketone bodies. Ketone bodies are short-chain derivatives of fatty acids. These shorter molecules can cross the blood-brain barrier and can be used by the brain as an alternative metabolic fuel.
After 2 or 3 days of fasting, the liver begins to synthesize ketone bodies from precursors obtained from fatty acid breakdown. The brain uses these ketone bodies as fuel, thus cutting its requirement for glucose. After fasting for 3 days, the brain gets 30% of its energy from ketone bodies. After 4 days, this goes up to 70%.
Thus, the production of ketone bodies cuts the brain's glucose requirement from 120 g per day to about 30 g per day. Of the remaining 30 g requirement, 20 g per day can be produced by the liver from glycerol (itself a product of fat breakdown). But this still leaves a deficit of about 10 g of glucose per day that must be supplied from some other source. This other source will be the body's own proteins.
After several days of fasting, all cells in the body begin to break down protein. This releases amino acids into the bloodstream, which can be converted into glucose by the liver. Since much of our muscle mass is protein, this phenomenon is responsible for the wasting away of muscle mass seen in starvation.
However, the body is able to selectively decide which cells will break down protein and which will not. About 2–3 g of protein has to be broken down to synthesise 1 g of glucose; about 20–30 g of protein is broken down each day to make 10 g of glucose to keep the brain alive. However, this number may decrease the longer the fasting period is continued in order to conserve protein.
Starvation ensues when the fat reserves are completely exhausted and protein is the only fuel source available to the body. Thus, after periods of starvation, the loss of body protein affects the function of important organs, and death results, even if there are still fat reserves left unused. (In a leaner person, the fat reserves are depleted earlier, the protein depletion occurs sooner, and therefore death occurs sooner.)
The ultimate cause of death is, in general, cardiac arrhythmia or cardiac arrest brought on by tissue degradation and electrolyte imbalances.

Interesting... I read the article and it said you can enter this state at 1,200 to 2,000 calories per day. This puts me at risk since I am at 1,630 net calories per day. I am only running a deficit of 750 per day though. I thought I was pretty safe.

The scale is getting a little stubborn and I was thinking of bumping up to a 1,000 calorie deficit but maybe I should do the opposide, reduce to a 500 calorie deficit...

Just a little tidbit about MFP that I've found... once you've entered your personal stats (weight, age, goals, etc), then daily input your food diary & exercise journal... when you submit that day's diary, if you are at risk, a warning will appear on the screen that says something to the effect of "you are not eating enough calories, and are at risk of your body going into starvation mode"... or something like that. I saw it a few times, and it really made me pay attention to how many calories I actually take in!

I was marathon training for months, on about 1200 calories a day... I didn't lose an ounce, and actually gained a couple of pounds. I'm not too beat up about it... I'm little by little, learning more about my body & how it works.

Interesting... I read the article and it said you can enter this state at 1,200 to 2,000 calories per day. This puts me at risk since I am at 1,630 net calories per day. I am only running a deficit of 750 per day though. I thought I was pretty safe.

The scale is getting a little stubborn and I was thinking of bumping up to a 1,000 calorie deficit but maybe I should do the opposide, reduce to a 500 calorie deficit...

Just a little tidbit about MFP that I've found... once you've entered your personal stats (weight, age, goals, etc), then daily input your food diary & exercise journal... when you submit that day's diary, if you are at risk, a warning will appear on the screen that says something to the effect of "you are not eating enough calories, and are at risk of your body going into starvation mode"... or something like that. I saw it a few times, and it really made me pay attention to how many calories I actually take in!

I was marathon training for months, on about 1200 calories a day... I didn't lose an ounce, and actually gained a couple of pounds. I'm not too beat up about it... I'm little by little, learning more about my body & how it works.

:flowerforyou:
Just a note on the MFP "starvation warning": it ONLY shows when your daily intake is under 1200, thats not 1200 NET calories, its just straight up 1200.... WE need to be sure the NET is making it to 1200~!!! I wish Mike would change the warning to 1200 NET calories, but until that happens, we need to be aware of this loophole and not accidentally overlook it and fall into thinking "i didnt get the starvation message so i must be ok" mindset! :noway:

Just a note on the MFP "starvation warning": it ONLY shows when your daily intake is under 1200, thats not 1200 NET calories, its just straight up 1200.... WE need to be sure the NET is making it to 1200~!!! I wish Mike would change the warning to 1200 NET calories

I know right!! If we should be staying about 1200 net we need to be warned. Often I am under that w/ exercise but didn't really intend to be it's b/c I didn't notice. I'll notice nutrients that are over or under and when I'm at 1150 cals and add more food in to get to 1200 but with 60min of walking a day and 35 min on the elliptical I shouldn’t go bellow 1500+ but my regular day is about 1350 so I am guilty of under eating for sure and would like a little MFP automatic warning tough love

Maybe everyone should be a little more understanding before automatically judging Julia when you don't know her history. Just sayin...

I absolutely agree. As I read through, I felt so bad for Julia. Not for her battle, but because it seemed like she was being judged (and a bit attacked!). She seems really nice...and honest. Alot more than most of us can say! I am sure we have all done some things to lose weight that were not very smart...weather it be from emotional issues or lack of knowledge. Either way, we are ALL learning and overcoming our issues...be it UNDEReating OR OVEReating.

But anywho, seems like alot of different answers/opinions on this. I consume at least 1290 calories a day. Some days I go over, but try to stay under 1400...but those are not my NET (though I rarely exercise :embarassed: ). I didn't realize that i need to keep my NET at a minumum of 1200.

'Starvation mode' as most people know it, is a complete myth.

To achieve a reduction in metabolism, a healthy individual would have to severely cut their daily required calories for a prolonged period of time. In 1950 a study was performed where 36 men were deprived of their daily caloric needs (as low as 50% below their daily need) for 6 months. The result was major weight loss, and 40% reduction in their RMR (resting metabolic rate). However the men CONTINUED to lose fat until the end of the study, or until they reached 5% body fat.

A reduction in RMR due to severe calorie restriction will not counter-act the resulting calorie deficit.

http://caloriecount.about.com/truth-starvation-mode-ft28742-1

Humans have evolved to handle starvation very well. Our bodies make great use of our stored fat.
http://en.wikipedia.org/wiki/Starvation_response (cited sources at the bottom of the page, for those Wiki haters)

This only studied 36 men, and should not be used as a generality. The point is, your body needs fuel to fuel your workouts, if you don't get enough you will a much higher % of muscle vs fat than if you were getting enough fuel.

The point is, your body needs fuel to fuel your workouts, if you don't get enough you will a much higher % of muscle vs fat than if you were getting enough fuel.

This really depends on your body composition. If you are lean and healthy, it is more likely that you will experience muscle catabolism when significantly reducing your caloric intake. However, for anyone that has a high percentage of body fat (such as individuals who are overweight, obese, or super-obese) this is not exactly the case.

In any situation -- as you lower your caloric intake, special attention should be given to what kind/what amount of macronutrients you are getting when trying to stay within your calorie limit.

The OP has less than 20lbs to go, so I am guessing he is either slightly overweight, or at the higher end of the healthy BMI range, and most likely has a moderate BF%.