Starvation Mode

Yes, it will go into starvation mode, if you don't eat more than your basal metabolic rate for a long time (and your bmr might be even higher than what mfp suggests). I think it will not go into starvation mode immediately. If you have a day with less and feel satisfied, you can just try to eat more the next day oder the day after. Just don't stay under your requirement for too long. If you already did so, maybe you're already into it and therefore you ffeel satisfied with that little?

If you can't reach your calories, try eating nuts in the evening. They have a lot of (healthy) protein and a lot of calories in small amounts (hazelnut: 600 kcal, walnut 650 kcal and peanut 550 kcal per 100 g)

Yes, it will go into starvation mode, if you don't eat more than your basal metabolic rate for a long time (and your bmr might be even higher than what mfp suggests). I think it will not go into starvation mode immediately. If you have a day with less and feel satisfied, you can just try to eat more the next day oder the day after. Just don't stay under your requirement for too long. If you already did so, maybe you're already into it and therefore you ffeel satisfied with that little?

If you can't reach your calories, try eating nuts in the evening. They have a lot of (healthy) protein and a lot of calories in small amounts (hazelnut: 600 kcal, walnut 650 kcal and peanut 550 kcal per 100 g)

NO...not this...

Starvation happens when you are eating vlcd for a long period of time and you lose weight, hair, get sunken eyes..starvation mode as understood by most is a myth.

So Yesterday MFP told me I'm eating too few of calories... but I'm feeling full so I stop eating. Is it still to few of calories if I'm feeling satisfied and will my body still go into starvation mode?

If MFP told you that you were eating too little eat more food...or eat full fat items (if you are going low fat) or have some ice cream, or poptarts..but get those calories in...oh and "hunger" isn't always a good indication that you are fueling your body enough.

There is no such thing as "starvation mode". That being said, if you ate very little for long periods of time you will slow your metabolism. But to do it by any significant amount that would be noticeable you would need to ate very little for long periods of time. A few days or even a week of starving completely, at zero calories, may not even do this. So you don't have to worry about it.

There are just so many BS horror stories online about starvation mode. You will not burn any noticeable amount of muscle if you fast for couple days. You will not stop losing fat if you fast for couple of days without food. You will not damage your metabolism completely if you fast for couple of days without food. And especially not if you ate some food, which you did, not fast completely.

Neither it is unhealthy for you to ate extremely low amount of calories. It isn't. As far as you get all the vitamins and important nutrients for your health you might as well ate 800 cals a day. Only reason why it is said to be unhealthy is because it is extremely hard to ate enough vitamins to be healthy. And of course you will not be able to maintain enough muscle mass and fat to keep it in healthy range, at least most people will not. But what I'm really telling you... "starvation mode" is and exaggerated BS. Just ate healthy most of the time and don't worry about being too low one day once in a while.