welcome to healthcare magic,
diet is a hormone based medication that you will be using to reduce your weight.
as your factor leiden b positive you have a higher chance of developing a clot, hormone based medication are a risk factor to throw a clot at any part of the body.
yes you have a higher chance of throwing a clot if you will be on hcg diet,
i would suggest choose another way of reducing weight, dont take risks.
would suggest visit your gynecologist for change of medication.
hope to have answered your query