You might want to mention that you are "active" and maybe list some of your activities. If you don't currently have any physical activities but would like to do things with someone you might say something like "I really would like to find a partner to get out and do physical things with such as hiking, working out, etc.
That way that give them the idea that even if you are overweight you are not a couch potato.

Don't mention how you want to lose weight (maybe in the first conversation or two but not on the profile) because while 'pathetic' might not be the correct word but I am sure there are plenty of people who are "gonna lose the weight" that never do so it may not be believable.

How many of us have bought or kept a too small article of clothing because we are "gonna lose weight"?

I totally understand where you are coming from because I was married to someone who was very sedentary and never wanted to do anything with me so I became that way myself (I take accountability for it too).
Now I have also had a lot of first or second dates and it seems to be dinner so often and not physical activities so I was still not active. I wasn't progressing to the point of doing physical stuff with the guys yet.

So, while I like going out to dinner I was still feeling very sedentary so I one, have joined a gym (still sporadic at attending it) but also joined some local hiking groups. So I now have been out on several hikes, gotten some great exercise and met new friends too! Check out Meetup. com. I don't know what they have to offer in your area but it is great for social groups too.

Another issue I have is that I tend to prefer men on the slimmer side even though I am not so that limits me somewhat and yes, a lot of slim people think that heavier people are not active or don't want to be and that can be very far from the truth.

Hope this helps. Good luck to you.

P.S. You might want to move this post to "Ask a Guy". You will probably get more responses.