Unhealthy People Eat Meat

Once in a while a study will come along that suggests that meat consumption reduces lifespan and increases incidence of disease. These studies are usually performed by asking people what they eat periodically and then taking note of when/how they die.

"People who eat meat die more quickly." Let's unpack that. Does that mean eating meat causes you to die earlier? What about this statement: "People who watch reality television have higher credit card debt." Does this mean watching Survivor will affect your credit score? Perhaps, perhaps not. Perhaps, poorer populations are more likely to watch reality television, and poorer populations are also more likely to have credit card debt.

So what else could these studies mean? It could mean that people who have overall bad diets/habits both eat more meat and die earlier, even if eating meat and mortality are unrelated (or even positively related). People who are more conscious are more likely to eat more whole foods, in addition to less meat because the common knowledge is that meat is bad for you.

If at some point, correctly or not, people determine something is bad for you, the claim eventually will prove itself. People who follow nutritional advice and watch what they eat won't eat it, and will live longer. People who don't care about nutrition will still eat it, and they will die earlier. Both will occur whether the "bad" food is really bad or not.

This has two implications. First, observational studies (that is, studies where scientists simply observe how people act) on diet are completely unreliable and perfectly useless except perhaps as the precursor to a controlled study (a study where all possible confounding variables--like an overall healthy lifestyle--are controlled for). Secondly, it puts an enormous amount of weight on the decisions of nutritional experts. One bad call will echo for as long as you let it.