10-20% of your body weight, while your body suffers and develops various symptoms due to insufficient calorie intake. And once you resume your diet, your body will aggressively absorb every bit of calories, meaning that the rebound is extremely fast. Because the body thinks you've had a serious environmental disaster, once the diet is resumed, the body will be working at its full potential to absorb food.

But you mentioned three meals, eating all the apples you still eat, and exercising. It's a much better approach than skipping breakfast and going on a hunger strike in comparison!

I suggest you, on top of that, eat vegetables and porridge for lunch, and porridge in the evening as well, and apples as usual. This way there are very few calories, and to ensure that the body will not be harmed.