People weren't always over weight, but now they are. The reason isn't important. Really, it isn't. The solution is all that matters now. That solution consists of two principles: Simplicity and Consistency.
....the diet. Forget about it. Change it later, or don't. You need something that you can actually do, but more importantly, something you can do on a regular basis.
Exercise is your solution. If you are desperate and willing to go to any length to lose weight, then you will try the following because it worked for me, and that's more than what you got right now, right?
I think that there are a lot of ways to lose weight; it's a complex issue that doesn't have just one single approach. The most effective way I've seen is through a diet change. If you simply change your diet, you can be lean without even exercising. Ever see the same overweight guy at the gym on the treadmill year after year? He exercises, but refuses to change his diet, so he doesn't get the results he wants. But the reverse works, too - look at Michael Phelps: you can eat 6,000 calories a day of whatever food you want, if you don't mind exercising for 6 hours a day.
I remember reading that Men's Health said it takes 22,000 crunches to burn one pound of fat, which is a lot more effort than simply changing what you eat. But even if you don't want to change what you eat, you can still lose weight by managing the calories you take into your body - this guy made a whole documentary about losing weight while eating a diet of fast-food but keeping his daily intake to around 2,000 calories:
http://www.amazon.com/Fat-Head-Tom-N.../dp/B005KGPZZO
During the film, Naughton goes on an all-fast-food diet, mainly eating food from McDonald's. For his daily dietary intake, he aims to keep his calories to around 2,000 and his carbohydrates to around 100 grams per day, but he does not restrict fat at all. He ends up eating about 100 grams of fat per day, of which about 50 grams are saturated. He also decides to walk six nights a week, instead of his usual three. After a month eating that way, he loses 12 pounds and his total cholesterol goes down. His HDL does go down, often thought to be undesirable.
Personally, I think the secret to success is going to bed early. Exercising is easy...
when you feel good. Some people are naturally gifted with high energy & find consistency easy, but based on the number of overweight people in America, that isn't the case for most of us. Being consistent requires willpower. If your energy is high & you feel good, managing is willpower is easy because you can choose what you want to do - it puts you in the mood to do stuff!
The problem is, we all stay up late & are too tired the next day to enforce those decisions. So when you're tired, you don't have as much energy, which means your willpower is low - how many times have you eaten some junk food you know you really shouldn't have, or skipped exercise and said "I'm too tired to do this" or "I don't feel like it" instead of pushing through? Again, some people have naturally high energy & can just push through that fatigue barrier, but most of us say "tomorrow" because we're constantly too tired to deal with it today.
So from my experience, if you're struggling with being consistent at eating a good diet & exercising on a regular basis (meaning you're not naturally a high-energy person who can burn through things at will), you'll get better results by going to bed early & getting enough sleep so that you don't run into the "too tired, don't feel like it" wall. It's a difficult problem because we all have a little kid inside of us who doesn't want to go to bed early. Plus we have electric lights so we can stay up past dark, and there's all kinds of distractions like nightlife, Netflix, the Internet, etc. to keep us up all night. I think the energy formula goes something like this:
Early bedtime + sufficient hours of sleep = good mood (high energy + strong willpower from a solid night's sleep) = ability to have the power to enforce your decisions (instead of saying "I'm too tired" or "I don't feel like it")
I have yet to meet someone who struggles with exercising & eating right who doesn't stay up late. Start going to bed early & within a few days you'll be feeling good enough to feel like cooking & be able to be persistent at exercising. You have to decide if that sacrifice is worth it...a lot of fun stuff goes on at night, but at the same time, that means that you're going to have to fight yourself on everything you want to do that isn't easy because you'll be just tired enough that everything is a pain to follow through on.