I have a few questions for you to pose to yourself, from a viewpoint of support for you as a fellow member of this community that you are lovingly accepted into.
Do you think his behavior is respectful, loving, uplifting towards you?
You do know that you aren't his property and don't need his "consent" to prioritize yourself or your health?
Does he have a fetish for bigger women and is your losing weight a turnoff for him (physically and mentally)?
Is he genuinely a friend who sincerely supports you with other endeavors in your life, without needing to personally gain/benefit from you/it?
Does he encourage you to build your confidence and self esteem daily?
Does he encourage your individuality?
Does he support you having healthy outside relationships with your family, colleagues and etc.?
Do you feel comfortable discussing your individual dreams, goals, achievements and vision for your life/future independent of his benefit?
Do you feel uplifted after talking to him and like he's a positive light in your life?
These are a few things to ask yourself and be honest with yourself about how you are truly feeling. 5 years in a relationship doesn't mean that you are being loved, supported and respected by your mate. I know that we don't know the entire history of your relationship, but he sounds cruel and controlling. His punishment that he's imposing upon you and his request to not be contacted until you can explain yourself to him what he will benefit from you is not the behavior exhibited by a person who cares for someone. He sounds insecure, manipulative and insensitive to your need to get your health on track. He's right there in the dictionary under narcissist!!! His attitude towards you and yes your mother too is disrespectful and you are worthy of being respected, loved and supported. You should be celebrated by your partner for your accomplished weight loss thus far and please don't dream of sabotaging your success and trying to stop your journey. We will cheerlead, shout to the mountain tops and yell praises for you to win!!
You are worthy, beautiful and deserving of whatever your heart desires.
I wrote this with the intention of being a supporter of your journey and not to preach or judge. This is the judgment free zone, I just don't like bullies who rain on other people's happiness and blessings.