I know that I am not extremely over weight I mean I could lose about 25 to 30 pounds. I gained weight fast because of the stereotypical college lifestyle. I don't think that I am ugly but underneath my clothes I am so self conscious of my ugly stretch marks. When a guys sees them will he be turned off right away?
Not if he is the right guy for you. Not to be an ass but to let you know how men are which is what you asked, yes a select few will be turned off by your stretch marks but that doesn't mean all men will be. If you are talking about a one night stand or just some fling, then yes the guy may be turned off a little but that won't stop him from sleeping with you. However if you are talking about a man who loves and likes you for who you are as a person, he won't even notice. I know what it like to be insecure about certain cosmetic faults of my own. It sucks because somethings we just can't change and we are worried how others will perceive us. As long as you do what you can to work on the things you can control and have respect for yourself you will be just fine.
Guys like naked girls. Hey will probably be more interested in your boobs and your happy place and won't pay attention to your stretch marks, certainly not the first few times you are together. If you are that worried about it, turn off the lights and light some candles or use a light dimmer or small table lamp. This will totally decrease the lighting contrast in the room so your stretch marks will hardly be noticeable or even disappear altogether.
These guys are right. Girls are SO much harder on themselves than we are. Guys are attracted to your femenimity, and when your clothes come off, we will far busier with your butt, boobs, vagina, legs, hair, and lips than any stretch marks. We don't care, we are busy kissing, and feeling, becoming intoxicated with the smell of your hair. The fact that your clothes are off is more than enough for us.
I think even girls a little over weight, like yourself perhaps, really overestimate how we react to the female body. Generally, guys are more sexually aroused by slightly overweight than slightly underweight.