I've been posting fitness content on my Instagram for while now and although overall I have made mostly new amazing friendships with like minded people, it has come along with some negative and judgemental comments from people in real life who do not understand my passion for fitness.
The most important thing to do is to understand that it does mostly come from a place of not understanding, people are very set in their ways and with that comes a negative view point for anything that is different! Fitness being one of them. It is supposedly 'normal' to hate exercise, love eating unhealthy food all the time and love being lazy and therefore if you love exercise and actually enjoy eating healthily, you're a weirdo! These people who believe that just do not understand our lifestyles and perhaps are even jealous that they are not fit and healthy and actually working towards their goals!
The second thing you can do is cut them out of your life! If they are really judgemental and bitchy, is it really worth keeping them around? Obviously if it's a family member you probably can't completely cut them out but at least try to cut out the comments, for example, try not to bring up the topic of health and fitness around them. This avoids the situation where they could potentially say anything that could annoy/upset you and makes being around them much more bearable! Find like minded people online who understand you to talk about this sort of thing with, and if you need one of those, you can always message me!!
Another thing you can do is just ignore them! They don't know what they are talking about! As long as you are happy with your lifestyle and life choices, why does it matter what other people say or think! You're living and enjoying your life and working towards your goals, that's the most important thing! As that saying goes, you do you girl! (Or boy!)