Being hungry does help you lose weight.
However it's not healthy to be too hungry and not eating enough food and not consuming enough calories is also very unhealthy.
To keep healthy and avoid passing out you need to consume at least 1,200 calories and if you consume less than 1,200 calories per day you can become weak and pass out.
And also your body becomes unhealthy.
Yes it is bad for your health to only consume only 1000 calories per day when losing weight or at any other time.
You need to consume at least 1,200 calories per day minimum to stay health because not enough calories can make you unhealthy although you may lose more weight by eating less than 1,200 calories.
As long as you're consuming at least 1,200 to 1,800 calories per day you can still lose weight and still be healthy.
Just don't starve yourself when doing weight loss.
When working on weight loss you still need to eat some food because our bodies need energy and we get very unhealthy and weak when we don't eat.
Some people have passed out when they were losing weight and not eating enough calories or not eating at all.
Yes you can lose weight by not eating for a few days or by eating a tiny bit of food but you still should not do that because it's not healthy.
I've heard of people eating so little that they got really sick and died.