If you want to be more physically attractive you don't want to just "lose weight" but look fit and healthy. How to do this isn't obvious, as mainstream health advice doesn't achieve this for most people. You should expect to spend considerable time researching and learning about fitness and nutrition. Look to emulate methods that work, not ones well understood by science- it is a myth that nutritional science has advanced to the point where we can design effective diet and fitness programs entirely from basic biological knowledge.

This is a good article on physical traits women find attractive, and how to cultivate them:

Male Physical Attractiveness Part I or: You Shallow, Shallow Ladies

The website contains good information, but it's also clearly trying to sell a particular fitness program (The Hollywood Physique for Men). I did this program myself and it worked exactly as advertised, but it was very challenging and time consuming to follow. I ate 11 eggs/day for 6 months, went to the gym 8 times a week, and was totally socially isolated- and very fatigued at times.

Still, afterwards it was very surprising how differently people treat me in social situations. I am a serious health/biochemistry nerd and like to go on and on about these things… people used to roll their eyes but now that I look different they want to hear what I have to say.