A lot of your friends and family will interpret beneficial growth/change/evolution on your part as a threat to their status quo.
This one is deep so I'll kick the bobo for a mo:
Everything in life is relational, meaning you're tall compared to someone small etc.. its how we create our mind map and why they say no man is an island. If you decide to better yourself - by losing weight, getting a new skill, improving your mind etc.. - people may initially support you as they feel its the right thing to do but once they see you're for real they'll clown, guilt trip and discourage you in a million subtle and not so ways.
Why?
Reason being is your change upsets their inner equilibrium - the famous discomfort zone most call home - as it moves a piece of their mind map in unpredictable ways which in turn alters their perception of self. In so many ways its got very little to do with you but all about them this is why if you ever plan on doing something big - never tell a soul, let the results speak for themselves.