In the article, Study: Watching Calories Takes Commitment, there's no mention of the various letters challenging the study findings as they relate to humans. In fact, a read of the article will leave you with the impression that the author's concluded that calorie restriction will extend your life span. In their published studies, they didn't reach that conclusion - in fact, they reported their findings as relevant to primate species and were careful not to extend their findings to homo sapien.
More troubling though is the Washington Post article statement that "Losing that extra weight is one thing. Keeping it off requires a lifetime of counting calories," followed two sentences later with "Genetic differences allow some primates to remain thin and others to grow fat when fed an identical diet over the years, the study found."
So, which is - did the thin monkeys have to restrict calories or not to remain thin? Apparently not - some grew heavier with an IDENTICAL diet as their thinner counterparts. Somehow that's totally lost in the article and we're told instead that only a lifetime of counting calories is going to keep us slim. On identical calories some grew fatter than others. The researchers chalked that up to genetic differences. The author of the article decided that calorie restriction solves that problem.
Discussion of the metabolic changes that were going on in those monkeys that grew heavier on the same diet - loss of insulin sensitivity, rising blood sugars, rising insulin levels, diabetes. In fact, insulin sensitivity, or lack thereof, was the leading predictor of death in the monkeys. As the study abstract states, "Hyperinsulinemia led to a 3.7-fold increased risk of death (p = less than 0.05);"
That's not specifically genetic - that's a specific metabolic process going awry.
Might genetics play a role in such declines in metabolic function? Absolutely.
Might it be something else, like the burden of long-term diet that may be inappropriate? Absolutely.
Might it be something else, like a combination of factors aligning to create a metabolic nightmare like the Perfect Storm? Absolutely.
We just don't know all the answers at this point in time.
We certainly have clues - and when it comes to humans, we know how deadly high blood sugars, hyperinsulinemia and metabolic syndrome are. Reversing these conditions can be as simple as changing your diet to limit carbohydrate consumption to limit the insulin response to high blood sugars and thus increase insulin sensitivity. Often, the result of carbohydrate restriction is a spontaneous reduction in calorie intake - that is, it happens without effort to restrict calories. That often leads to weight loss, increased insulin sensitivity and overall improvements to risk factors.
Yet, this fairly simple approach is not the standard of care - instead we insist one must eat a low-fat, carbohydrate rich diet to avoid that nasty fat, use an assortment of pharmaceutical interventions to "treat" the symptoms and manage insulin levels, and watch helplessly as the inevitable happens - decline and degradation of the body.
Calorie restriction may alleviate some of the symptoms, but it's not reversing the condition, it's not addressing the root problem - high blood sugars. To fully tackle that issue in the metabolism, only one thing effectively works without drugs - restricting carbohydrate!