Random thought about cals+starvation mode

Hey,

    So my mom is going ona  diet (I went on one several years ago) and we were having a discussion about "starvation mode"....why is it that your body goes into a starvation mode at a specific calorie level below your normal intake? Like why won't your body go into starvation mode at like 1200/1500 (which are averages for losing weight for men and women) even though those may be well below what you normally consume? According to starvation mode, won't your body ultimately go into this regardless of your calorie deficit and ensure your weight gain once you stop dieting? Just something I am wondering

Nope.  Do your research and you'll find that "starvation mode" is highly overused and a complete myth at those calorie levels.

When you restrict your calorie intake at any level - 1200, 1500, 1800 - your body will compensate by burning less calories and becoming more efficient. There is no magic number. The more you restrict, the more efficient your body becomes.

The body definitely does become more efficient the more FIT you become (not neccessarily the less calories you consume).  And that is a good thing.  We WANT to have a more efficient body, and have it require less fuel.  People don't like to look at it that way, but that is truly part of being healthy and fit. 

Yeah, unless you're not eating enough to fuel your basic needs.  Then you're just asking for heart problems.

so basically everyone who diets goes into a type of "starvation LIKE mode" except the level where you "stop" at is what is important (i.e. enough to keep you healthy and be practical to live by)?...or am I way off base

I like to think of it more as "conservation mode" or "famine mode."  We evolved under conditions in which food was not always plentiful.  The ability to store fat is an adaptation that allows us to get through the leaner times until enough food is available and we can replenish our fat stores again.  It stands to reason that someone who was able to make their fat stores last longer through hard times was more likely to survive those hard times.

Our bodies are meant to burn fat when faced with an energy deficit.  BUT, when we contiually undereat, we are essentially telling our bodies that there isn't enough food around and there might not be for awhile, so it conserves energy where it can (I believe this is what sybil878 meant by our bodies becoming more efficient).  There are a number of different ways our bodies conserve energy.  Burning muscle is one example, since muscle consumes more energy than fat does.  Making our organs function with less energy is another example.  If the body believes, for instance, that decreasing liver function a bit temporarily will give it the ability to survive a little longer until there's more food, then it will do that (obviously, our bodies aren't actually thinking, and this is all due to a complex web of hormonal signals, but anthropomorphizing helps me).

There is no magic number.  There is no number of calories you must eat to prevent "starvation mode."  However, the lower you go, the more the body tries to conserve energy.  The amount of energy you burn is dependent on the amount of energy you consume, and there is no equation to predict this.  Everyone is different.  You have to find what works for you.

I was scared at this thought, too, wondering why such a mode would happen to completely stunt my weight loss when biologically we store fat to burn it later when our body deems we need it.

Honestly, don't worry about it. Really. If you're eating as much as your doctor, or any healthy site recommends, you'll lose. My own doctor said weight loss is as simple as burning more than you take in. Since February 2nd to July 23rd, I've lost a total of 101 pounds (323lbs to 222 lbs), and all I did was eat less and go to the gym 6 times a week for an hour of cardio and 15 minutes of weights.

Just do what your doctor recommends and let your body take care of itself. :)