Ive become a victim of bullying at work because ive just lost 4 stone and i don't know what to do?

ive lost a lot of weight so that meant i needed new clothes, i love the new me but i haven't changed whatsoever i don't brag about it or anything, 2 women i work with are giving me a hard time, they have been trying to lose weight but haven't been able to, so now they are calling me behind my back and trying to get other work friends to turn against me, i got on with them ok before but was always wary because i knew they could be trouble if crossed, they hate anyone who has more than them or who looks better, they are quite bitter about the pretty younger women who work with us but im the same age as them ( 50s ) im starting to feel very uncomfortable if anyone compliments me on my new appearance where they are because you can see the resentment on their faces, they are the type of people to spread lies just to get at someone, how can i sort this out, any advice would be appreciated.