I do believe that sometimes sincerity can hurt as much if not more than a lie to you and to others included.
But for example i try to be as open and sincere as possible with close people, if my girlfriend would ask me if shes fat and she was, i would say, yes you are fat, but with different words and different approach, we cant always be blunty sincere, but i dont think it would be a good thing to for example lie to that person and say, nah you are not, i would probably say something, "well maybe you gained some weight, but no worries we can start to go to gym or exercise together, that would be fun i feel like i got very lazy myself, maybe lets try to cook and eat clean fro a couple of months, just to see where this could bring us? SOmething like that".

This sentence would include some white lies about myself, just to make other person feel better. Aka "i want to try eat healthy, i want to exercise and so on". Thus i dont think that all lies are bad, you cant be 100% sincere all the time, mostly because other people have feelings and different approaches to different things. Of course there is a really thin line between those "white" lies and the evil ones..