Some people's weight issues aren't easily solved. When you're younger weight can be manageable if one takes steps to do so, but as one gets older its harder to lose weight consistently. Like it or not, weight problems can be genetic. One can eat healthy, exercise and still not meet the target weight for one's age/height.
However if one chooses to ignore one's health, does nothing to at least mitigate it, then one must accept the consequences. Consequences being overweight and unhealthy. No one should be shamed into losing weight, but a healthy dose of reality checks and constructive criticism is not wrong.
It all depends on the person, but if that person's diet is junk food then you are what you eat.
I've no respect though for people who blame society for their weight problems. No one is forcing fast food down one's throat, that is a choice. We all have choices to make in life, and learning everything one can about one's own metabolic rate, proper diet and self-control is the best choice one can make to be healthy.
Beyond any of those points, it is up to the person to get help for their problems. I have a friend who would complain about his weight all the time, how he can never get a girlfriend because of it, then he would go and order enough food to feed 3 people and eat it all in one sitting. After the first time I saw him do that, I told him straight up if he ever bitched about his weight to me again I'd smack him upside the head because he was just being stupid. He did nothing to change his habits, just wallowed in self-pity. I've no time for people who complain about the hand dealt to them instead of doing something about it. As I say, we all have a choice. Making the wrong ones then acting shocked over the consequences of said choices is the wrong attitude to have.
I'm bipolar, while that isn't a weight issue its still an issue. I don't use my illness as a crutch to be an asshole to people, I do everything I can to mitigate it and own up to when it gets the better of me.
Advice for overweight people, going off the same model I use for my illness:
1. Get a support group. Not necessarily joining something like overeaters anonymous, but people who care about you and who's opinions you respect. People who aren't afraid to call you out on your bullshit when you're lapsing into old habits. Having others you trust to be your sounding board is immensely helpful as being human we tend to ignore things about ourselves.
2. Set small goals for the present and near future that add up to one larger goal. Do not set unreasonable expectations on yourself, thats just setting you up for failure.
3. Keep a journal about urges or bad feelings that may cause you to relapse, then contact your support group if those feelings/urges become overwhelming.
4. Change everything you do, eliminating as many bad influences as you can. Whether its people you hang around that contribute to your poor habits, or just the route you take to work or school that passes by temptations to relapse. By making small changes like those mentioned, you may find your life is already changing. Also check your kitchen for food that is high in fat and sugar content. Don't drink diet soda, that does not help at all. Instead find a healthy alternative, like fruit juice (real not the "fruit" juice that is mostly sugar, flavoring, water and dye). Also carry healthy snacks with you to cut down on eating urges, again fruit is a great substitute and it is a "good" sugar type.
5. Accept that you may never be thin, and that is ok. But you still can lose weight and be healthy without being thin.
6. When deciding to exercise, it would be a good idea to set aside the money one would normally spend on junk food, fast food, etc. for a visit to a professional nutritionist. Not one of these "I'll make you thin" charlatans, someone who knows how to tailor your diet per body/blood type.
----6a. Blood type diets may not help you lose weight, but they can help mitigate cholesterol buildup in the body. There are various resources out there to help you figure out what foods are best for your blood type. You may also find you feel better once you're used to the diet.
7. Unless you're in absolute medical need, do not get any elective surgeries to "cheat" your way thin. This can lead to complications down the line and it also doesn't change your overall habits. There's no fast fix for anything health related, especially weight.
8. You don't need fad diets either, nor specialized foods to help you lose weight. Anything you can buy at your local market can work, but be proactive and read the nutritional values printed on pretty much every food item out there. Stay away from frozen foods unless its meats that you're sure won't cause heavy weight gain.
My examples: I do have weight issues, but not obesity. I was underweight for years, possibly anorexic (wasn't diagnosed, not a doctor) but I was disgusted with myself when I was in middle school because I was chubby, so I would starve myself to the point of sickly thin (think Christian Bale in the Machinist). Incidentally its how I found out I have an extra pair of ribs, but I digress. When I woke up and realized how dangerously thin I was, I found a diet to match my blood type (O+). It consists of mostly lean, white meats (chicken, fish, pork with little to no extra fat) veggies (I love me some good veggies in hollandaise sauce) and light grains, beans and dairy (I love butter but I take it easy on that). As it stands now I'm 165 (fluctuating up and down) but its the healthy weight for my height and muscle mass. I feel a lot better, but I admit I cheat... I love bacon and eggs, so not healthy but I also don't eat them all the time (though bacon would be my all time favorite meat).
I don't expect my experiences will change people's perspectives but if I can help one person, then I am happy.
Ending note: If any of you feel you have weight issues and need someone objective to talk to who won't put up with self-shaming and excuse-making (stinkin' thinkin') I don't mind lending an ear and giving advice if asked. PM me if you feel you need a friendly "ear" to talk to. I'll do my best to help, and be warned; while I won't shame you for your weight, I will call you out on bullshit. So if you're too sensitive to someone giving constructive criticisms, and sometimes kicking you in the metaphoric ass, then it may be best to find someone else. However beware of enablers, they aren't helping you. Feeling sorry for someone and standing idly by as they destroy themselves is almost as bad as if you'd done it yourself.
EDIT: Also go through your wardrobe and find clothing that makes you feel good about yourself, don't concern yourself with fashion statements (but if you can pull it off, by all means do so). A good self-image goes a long way to recovery.