The body image debate have been around for several decades, but even if consensus is clear; you could be good enough the way you are, the issue remains. Why? The most common answers are body pressure from media/fashion or picky dates. And even if you will find media that suggest you should try to meet an ideal body, or dates that only find you attractive if you look a particular way, that is not the problem. In fact, there is no problem. This is the way it is suppose to work.
Can we blame media? Fashion magazines and Instagram-models is made by the viewer. If your publications show what the viewers want to see, they succeed, if not they fail. Viewers vote on the trend with their attention. There is also opposing ideals. Thin vs. fit and even fat-admirers. Naturals vs. synthetic. Hipsters, bikers, classic +++ I wouldn't even know them all.
Can we blame potential partners? We are all entitled to our own preferences. If you are attracted to someone with a preference you don't match, you could feel the need to adapt. But maybe you should question if this partner is a good choice instead. There will be other potential partners with broader, more fitting preferences.
What the body image issue comes down to is human nature and the battle for higher social status. The closer your looks is to the current perceived ideal, the more people will admire you and be attracted to you. Sounds awesome, where do I sign up? Obviously you sign up by striving to reach the ideal body. You use makeup, diets, exercise, fashion and cosmetic surgery, and you follow media and fashion to keep up with the current trend and to get advice. This may feel like an obligation, because the feedback of admiration fell so good, but it still is a choice.
This isn't new. Look at paintings of ancient kings and queens with jewelry, wigs, powdered faces and fancy cloths, you see those with the means to present higher social value, will do so. So, why does it seam like this have started in modern times? There are several reasons. The most important reason is more people have access to more resources. When your basic needs are meet, you can use the rest of your resources on your status. You buy nicer cloths, jewelry, makeup, flashy cars, bigger house or cosmetic surgery. You can change your diet, use more time on exercise, and then show of "the better you" to the world. The more people that are willing to use resources on status, the more conditions and details will be added, to differentiate between peoples status. Everyone can't be a ten.
The second reason is access to more products and technology. Cosmetic surgery are getting better, and more procedures are available. Makeup come in more colors and textures. There are more to pick from in cloth, accessories, cars, and any thing you can buy to improve your appearance or status.
This also relate to the third reason. The speed and accessibility of media. With faster and more accessible media, ideals is constantly visible, and trends can change fast. "How to", "where to" and "what to" guides is in your favorite fashion magazine or a few click away on internet.
There are trade-offs. First one being the sacrifice needed to reach the ideal. The diet, exercise and surgeries needed can be harmful to your body, and in some cases give a less ideal body. Examples being yo-yo dieting or cosmetic surgery gone wrong. There is also the economic and personal investment you need to put in.
Second trade-off is the brutality and cynicism of the status game. Even if every social active human have at least a vague understanding and interaction with the status game, it will be much more brutal on the top. Climbers want your spot, and will use any means to break you down. And admirers can leave fast.
The third trade-off is the result of the second one. If it is more brutal on the top, it follows that it more comfort and warmth lower on the ladder. The ones admiring you will look at less status driven qualities, friends will be there to enjoy your company rather then look for spillover status and fame, and the ones attracted to you, will accept more deviance from the ideal. They will obviously also lack high status traits themselves.
To end with some kind of conclusion: Should you strive for the ideal body and higher status? If you are happy with your dating-pool, your friends and your self. Why bother? If not, self improvement isn't necessary a bad thing. Watching what you eat and exerciser can improve your health in addition to improve your looks. Dressing better can be as simple as finding better fitting cloths. My suggestion is drawing the line, if you are sacrificing your health and economy. And do remember, it is not an obligation, it is a choice. If you feel forced to do things you don't want to, your source of advice is probably not a good one.