This study fits in with a large array of similar research on other species of mammals. Many of them have found that calorie restriction is associated with a significant extension of lifespan in the model species being used.
There's also some theoretical underpinnings that render the idea plausible. Free radicals are the cause of a number of processes that we collectively refer to as 'aging'. Since free radicals are a product of metabolizing, the reasoning goes that if you eat less you might produce less free radical in the first place, which in turn might lead to less aging.
If this study is accurate, then it suggests that the aging process in primates may not work quite the same way it does in rodents. And who knows where further research into something like that might go; at the very least learning more about primate biochemistry is a good way to figure out potential new treatments for human diseases.
It's not a big surprise that finding an equilibrium in this relatively new food and mobility environment is difficult for our species.
Evolution tuned us to survive in a world where food is scarce and periods of starvation are frequent. In the rare occasion that you have excess food, you eat it and build up fat reserves. The saved up fat will help you survive the period of starvation that undoubtedly follows.
I wonder if there are any studies correlating obesity levels with reproductive success, and success of the offspring produced. That is what should end up controlling the genes and behaviour behind all this.
We didn't have processed cane sugar and refined vegetable oils during all those years of evolution.
The danger here is calorie-dense fatty foods. Things like almonds and cashews are ridiculously easy to overeat, because they take up relatively little space and have a very tiny effect on blood sugar levels.
edit: wow, why the downvotes?
I wouldn't say that's the danger. How many overweight people got that way because they eat too many cashews vs. guzzling liters of soda?
In any case, more people get fat off guzzling soda because soda is significantly cheaper, and are served in virtually every restaurant.
No, it is not. Satiety is a complex process mediated and regulated by a certain number of hormones. Leptin controls satiety, whilst the release of ghrelin induces the feeling of hunger. There is no difference between eating pure sugar and potatoes, as the latter breaks down mostly into glucose, anyway. Eating both will give a blood sugar spike but won't stop you from gorging on both unless your body promptly starts releasing leptin.
When we talk about longevity these days, we're not talking about living long enough to raise children — we're talking about living way past the point where we serve any clear evolutionary purpose. Thus, evolution might not be the best guide.
TL;DR version: eating the right things can help you stopping when you're full...
If this is right then your advice will work for a significant proportion of the population (maybe even a majority) but that it won't work for everybody.