What exactly is happening when your body enters “starvation mode” ?


If the body needs calories to survive, how can it go into starvation mode and slow down the metabolism? I hear of people trying to lose weight who can’t because they aren’t eating enough calories. Does your body shut down certain systems? If there is a base minimum, how can “starvation mode” change that on a biological level?

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To clarify, by starvation mode you’re asking about a person who has maintained a caloric deficit for a sustained period of many days or weeks, not someone who hasn’t eaten in 6 hours?

Short version: The body’s metabolism slows down. This results in a loss of energy and general lethargy. Slow thinking, slowed reactions, general malaise and lack of energy. Tired all the time.

The body begins to consume fat stores. Once those are gone, it begins to consume muscle tissues. The body begins to shut down nonessential functions. You begin to have serious issues with your kidneys and liver as they weren’t designed for this.

Your eyesight begins to go. You’re sleeping all the time. You eventually get reduced to skin and bones. You suffer brain damage. At this point, any kind of physical trauma can result in shock and then death. If you survive to this point, you’ll go to sleep soon and everything shuts down and you die.

This is how my doctor explained it. When you dont eat for as long as 12 hours your red blood cells starving for energy send distress signals to your liver. Your liver responds by releasing whatever reserves it had. After that? Your body will literally cannibalize itself! What ever fat stores your have it will use that as an energy source. If you have a pot belly you’ll see it go in a matter of days because fat is being used to feed the starving red blood cells. When that runs out? You die! Because your body will consume anything to feed itself, cannibalization. Organs will shut down and the brain will begin to die.

Another note to add onto what others said is that your body will divert blood from areas in the brain to the body which is why people who don’t eat for multiple days become disillusioned and start to break from reality. Body will send blood to the stomach lining to provide what minimal sustenance it can abs things like the eyes, smell and taste will start to go.