Don't worry, once the stressful event has passed, your hair thickness will usually return to normal within a few months. — Freepik
If you lose a lot of weight, there is always the possibility of hair loss. This hair loss is temporary.
People can lose a lot of weight through dieting or after surgery, especially if you have bariatric surgery, the kind that restricts your stomach’s capacity and makes you feel full more quickly. At the same time, this weight loss causes stress on your body and makes you nutrient deficient, pretty much like starvation.