Just going back to the starvation mode bit for a minute, would it not depend on how overweight you are in the 1st place? If you are fairly lean with just a bid of padding and not far off your ideal BMI, I could accept that easier than say if your BMI put you in the obese category and your body had an abundance of fat to burn and enjoy life with.
So my question is, if you are obese and went on a very calorie controlled diet (say 500 to 800 calories a day for a male) why would the body go into starvation mode when there is fat to burn and use up? Serious question, not being a smart ass...
It's true, the amount of body fat you have will dictate how large your deficit can be. But that does not mean you cannot be obese and still enter starvation mode. Consider a few other factors involved:
-Starvation mode is a hormonal response that changes how our body prioritizes energy utilization and storage
-When someone is in starvation mode, the body will reduce energy output as much as possible and increase lipid storage (fat storage)
-Starvation mode usually doesn't occur until someone has been under eating for at least 3 days. Why 3 days? Because that's about how long (minimum) it takes for your body to burn up glycogen stores, it can take longer (and usually does) if the amount being pulled form glycogen stores is small, but it almost never is shorter (this has been tested numerous times in research).
-The very basic calculation for whether someone is going to enter starvation mode is this:
Starvation mode is when the body cannot sustain energetic homeostasis. That means if the calories you consume PLUS the stored energy release rate in the body is less than the calorie needs of the body. Stored energy release rate is classified as how much energy the body can convert from fat the body can mobilize and use at any one time PLUS energy derived from glycogen PLUS energy derived from the conversion of amino acids into ketones. You add stored energy output to the output of calorie intake, look at the concurrency (how much energy is delivered at any one time) and if they don't equal the body's need for energy then you're looking at starvation mode.
Starvation mode will change the way the body releases hormones, which will trigger changes in many body functions (fat storage, energy use, organ output...etc.)
If you think this was complicated, try reading the actual explanation, it's killer, I was a chemistry major in college and it still took me 6 months to figure this stuff out.