Is it permissible for a woman to have her fallopian tubes tied for birth control with the aim of losing weight?

It is not permissible to use treatment to prevent or stop pregnancy except in cases of extreme necessity, as determined by reputable doctors. For example, if childbirth causes exhaustion, exacerbates an illness, or if there is fear of death due to pregnancy, provided the husband agrees and the necessity is alleviated. Weight loss does not reach this level of necessity, and it may lead to the exposure of 'awrah (private parts). Therefore, it is advised to follow the guidance of the Prophet, peace be upon him, regarding moderation in eating: "Sufficient for the Son of Adam are a few mouthfuls to keep his back straight. But if he must eat more, then a third for his food, a third for his drink, and a third for his breath." It is also permissible to use permissible methods such as coitus interruptus during intercourse, as there is no harm in coitus interruptus without a specific reason.