Ok, but if that many people are given an opportunity and refuse shouldn't we wonder about the underlining reason?
Roughly 35% of adults living in the US are obese - this comes to about 90 million obese adults. While I've not talked to all of them, I'd venture that a vast majority of them know of the negative affect their obesity has on their health and would prefer being a healthy weight. I'd further suggest that most of them have tried to lose the excess weight, likely multiple times, and have failed.
The equation to lose weight is quite simple - burn more calories than you take in. Live at a 500 kcal/day deficit and you lose one pound per week. There are complexities associated with this, but that's the basic equation.
Are these obese people lazy? No, not all of them. Many of them get out and work physical jobs every day that you or I likely couldn't, at least without some time to acclimate to the work load.
Is there something genetically wrong with them where it's not their choice? In some cases, yes, but a vast majority of obese people are overweight due to lifestyle choices - even if those choices were their parents' choices and they never knew any different.
The issue is that losing weight is difficult - it takes a long time and one has to be disciplined in multiple areas of their life if they wish to see long-term success. These people have every reason to lose this weight - none of them want to die in the mid-50s from heart failure, like many do, but it's hard to do the work daily and see little success, because losing weight is a long game and that doughnut tastes really good
RIGHT NOW!
It's no different from the poor, in my experience. It generally takes a lot of work and long time to climb out of poverty into the middle class. Many behaviors have to be changed, lifestyles almost always have to change, expectations have to change, and short-term goals must be ignored while working for the long term goal of rising above poverty.
Just as few have the self discipline to lose extra weight, few are willing to choose to do the long, hard work to improve their economic station in life. The avenues are there, as are resources, but it doesn't happen overnight, and that shiny car / big screen / latest iPhone is right there, within their grasp.
Being poor is really hard and very expensive - we've discussed that at length here before. But with tenacity and self-discipline virtually everyone can choose to climb out of it in the US. It's why people continue to climb walls and risk crossing dangerous deserts to try to get here.
(Let's please not turn this into an immigration or Trump discussion - this was added to highlight the reality that the US remains a land of opportunity...)