Also, please note there is more to exercise than cardio.
However, excercise does have other effects, possibly including reducing cravings and changing hormone levels and maybe (over the long term) gene expression.
I can and have lost eight pounds (not water) in three days. I could do it right now. I call BS on whatever research.
A pound of fat is roughly 3500 calories. In order to lose eight pounds of fat in three days, you would have had to induce a caloric deficit of over 9000 calories per day.
A note to everyone: The most weight you can healthily lose is about two pounds per week. More than that and you're going to start losing a measurable amount of muscle mass. The exception is when you first start out exercising and eating properly, but that should only last for a couple of weeks.
I specifically said it was not water.
In other words, sorry if you don't believe me, but much of what you lost was water.
Of course proper diet does have a huge effect in weight loss though.
The problem with exercise, like many endeavors, is that the results are from long hard work. Many times as soon as the initial results slow to a crawl people will lose pretty much all motivation. Its the same as anything else really, burnout is not caused by the work but by the months of seeing no results.
I mainly exercise with weight training (5-6 days a week) and cardio maybe 2-3 times a week. I have been exercising regularly for probably about 8 years now. I don't do it for muscle or weight loss anymore (but of course I enjoy those effects) I do it to get away from everything. Its the time when I can really clear my mind and do something is mentally very easy (although many times physically difficult).
I think exercise is the best thing for people that spend many hours doing mentally challenging but physically non-challenging work like programmers or engineers.
On more than one occasion, I've made relatively mild cuts to my caloric intake (say, 250 Cal/day), and lost significant (>10 lbs) amounts of weight in 1-2 month time periods (and I've kept it off for years). Right now, I maintain my weight (6'2", 180lbs) by eating about 2,300 Calories per day. I don't count Calories anymore (I can estimate pretty well), but by weighing myself daily, I adjust what I eat to maintain.
People think that calorie restriction doesn't work, because they don't give it enough time, they aren't careful about it (i.e. sloppy record keeping), or they cheat. But if you're diligent, patient and honest, it's the most effective weight loss routine you can establish. I recommend using something like calorie-count.com to keep track of everything that you eat for a week or two, then cutting back on that number by a small amount (say, 250-500 Cal.) for a month. You'll be surprised at the results.
Just cut back on soda. Eat half a burrito instead of guzzling the whole thing. Eat proper meals instead of snacking on candy bars.
Just the basics.
I've never dieted, but I'm down at 177 pounds from 189, since I thought I was getting a bit heavy, just through using the techniques above.
I suspect the largest contribution is from not eating an entire Chipotle burrito every couple of days, but instead eating just half, which is still a pretty good meal.