There's no reason to hate your body.
Here are some reasons why:
1. Realize that God created you just the way He wanted you to be. I don't know anyone who looks at the trees in the fall when they're all orange and yellow and gorgeous and just absolutely hates the way they look. It's hard to hate something that God created. The same goes for your body. You ARE fearfully and wonderfully made and it looks so good on you.
2. Think of yourself as a child. Would you go up to your five year old self and say, "Wow, I hate the way that your legs look in those jeans? You should lose weight." Of course not. That's the same thing you're doing to the body that you look at in the mirror every day.
3. Don't say harsh things about yourself around others. If you're going around and constantly expressing your hate for your body. You are going to just tear yourself down even more and you will also tear down others. If you express that you think you're fat around your friends, one of them is bound to think, "Well, I'm bigger than her... What does she think of me? Am I huge to her?" It happens so often. Don't spark that in other people and don't continue to tell yourself hurtful things.
4. Be healthy. I'm not saying never eat ice cream or macaroni and cheese and work out seven days a week. I'm just saying, go for a jog, do Zumba or yoga, or go for a hike. Get outside (or in a gym) and do something that you truly enjoy that benefits your body. It will release endorphin and you'll feel much better. Also, try to work in a healthy breakfast to fuel your body throughout the day so that you feels more energized and ready to go.
5. Think about all of the wonderful things that your body can do. We forget that our body has a use other than being looked at. Think about all the places your body has taken you today. My legs have walked miles today. My fingers are typing this post. My lips have kissed someone that means the world to me. My arms have hugged people I love. My eyes have read the words off of a book that has changed my life. One day, my body will wake me up, my hands will fix my children breakfast. One day, my legs will go on walks with someone I love. And one day, my eyes will shut and they won't open again. Enjoy the body that the Lord gave you and enjoy it while you have the chance.