During Starvation mode the body will only first burn off your fat reserves after it exhausting the contents of the digestive tract (what you just ate), and then your glycogen reserves stored in your muscles and liver cells. Once those are gone, then it will actually start to burn your actual muscle tissue, the body would have used up its reserve of glycogen after about 6 hours.
The Starvation Mode usually activates in people who fast on a regular basis, including those who are sticking to a calorie restrictive diet..The brain requires about 120g of glucose per day to stay alive. Now, if you are in starvation mode, after about the 3rd day you will start to use what are know as ketone bodies in replacement of glucose. However, it needs about 30g of glucose per day even with the ketone bodies. Now, it will get about a two – thirds of this by the liver from glycerol. And then the remaining third from the bodies own proteins, your muscles.
You would think that in starvation mode that your body would actually use the fat reserves you have, it will, for the first few days, then your metabolism will become more efficient, and want the lean proteins from your body. So, you will stay fat, but start to lose muscle in the process. And guess what? Muscles are the key to your metabolism, the more muscle mass you actually have, the higher your metabolism is.
Now, there is away to prevent this starvation mode from happening. Most people eat only 3 meals a day, and maybe a snack in between. What you should actually do, is of course eat breakfast, and then 3 hours later, eat a nice healthy snack, like some fruit, or a protein bar. Then 3 hours later eat lunch, then again, 3 hours later a snack, then, again, 3 hours later dinner.
So, lets say you eat breakfast at 7am, then you would have a snack at 10am. Then lunch at 1pm , then another snack at 4pm, then lastly dinner at 7pm. What this will do is prevent your body from entering starvation mode, using up its reserves, and then slowing down your metabolism in the process, which is what happens, because your weight loss drops off, and plateaus.
Now, sure, the full fledge starvation mode will not happen for about 2 – 3 days, however, if you do not in properly, then it will happen. Meaning, you need to have a proper intake of calories, and the right foods at the right time, so that at the same time as staying out of starvation mode, you are keeping your metabolism up to speed, thus in return, you will either maintain your weight, if that is your goal, or lose it, if that is your goal.
Now, one last bit of advice about your bodies starvation mode, eating a low carbohydrate diet will actually trigger this in your body. Because, carbohydrates are your bodies main source of fuel, after that, its protein which means, your muscles. Yes, you could eat a high protein diet, however, the protein we take in, can not all be used by our body to refuel itself, it is usually used to maintain the body, by processing the proteins, and putting them where they are needed to build the body, like your muscles.
It is best to eat a well balanced diet, all depending on your goals, if you want to lose fat, maintain your weight, or, even to gain. It should be a well balanced with the right amount of carbohydrates, protein, and fats.