Let’s face it. People feel the fat-antifat kerfuffle is a struggle between good and evil. Gluttony is bad! It’s not gluttony. It’s a disease! It’s not a disease. It’s genetics. It’s okay. It is not okay. And so on and on.

Folks, we’re talking about biology. It could be all of the above and then some. “Then some” is actually my preferred answer and I’ll discuss it in a bit. But in the meantime, it’s worth remembering that none of the above are mutually exclusive. The answers vary from person to person and there is no single thing that is true for everyone, or even for one person all the time. As they say on Facebook, it’s complicated. In that spirit, it’s well worth looking at research that tells us about parts of the answer.

Gary Taubes writes about a study in the Journal of the American Medical Association (Ebbeling et al., 2012) on What Really Makes Us Fat:

[T]he study tells us that the nutrient composition of the diet can trigger the predisposition to get fat, independent of the calories consumed. The fewer carbohydrates we eat, the more easily we remain lean. The more carbohydrates, the more difficult. In other words, carbohydrates are fattening, and obesity is a fat-storage defect. What matters, then, is the quantity and quality of carbohydrates we consume and their effect on insulin.

Chalk one up for the Atkins Diet, but don’t therefore assume the American Heart Association is “wrong” when it tells you to eat a low-fat diet of whole grains, fruits and veggies. The AHA is trying to help your heart. Their advice is perfectly good for your heart. The Atkins Diet is trying to help you lose weight. This research says it does. It says nothing about your cholesterol or the kidney-damaging effects of long term excess protein, especially in people with borderline kidney disease they may be unaware of.

The research shows an interesting piece of the obesity puzzle, but unless fat storage regulation is the biggest reason for obesity, it’s not actually going to deal with the epidemic. And the biggest causes can’t be fat storage regulation gone awry. Human physiology hasn’t changed in the last few decades. We have the same fat-storage hormones we’ve always had. Likewise, people have always wanted to eat too much. Nor have our genetics changed a whole hell of a lot in the last few dozen years. And yet obesity (as medically defined and meaning more than mere overweight) has gone from being a rather rare issue to being a problem for a third of all US adults.

The thing that’s missing in too many current discussions of the obesity epidemic is environmental effects. This is not a comment on the research, because that wasn’t its topic. But every single discussion for the general public needs to beat that drum until we all get it. Environmental factors are the only ones that have changed recently. Plus, that explains why we have an epidemic. Epidemics are public health issues, and they’re all embedded in the environment.

The reason it’s so important for everyone to understand the biggest causes is because obesity really is an epidemic, and it really is destroying the health of millions. It’s causing and will continue to cause horrible suffering in people who go blind or need amputations due to diabetic complications, or who become paralyzed after strokes. This stuff is no joke. Nor is it just a conspiracy by the fashion industry (although it’s that too). To the extent that obesity damages health, it’s vital — literally — to understand and fix the real causes and not to waste time on sacrificial food offerings to gods who don’t care.

I think two environmental factors stand out like sore thumbs.

• Advertising for fat-making food and drink
• Endocrine disruptor environmental pollution

You may not think of ads as an environmental factor, but what I mean by that is it’s out there, in your environment, and not something you control. You can’t simply ignore ads, no matter how many people blithely tell you to. Ads have their effect whether or not you pay attention. Your only real choice is to turn them off. An individual can choose to eschew most media, but on a population level, that’s not going to happen.

So we’re in an environment saturated with unavoidable messages to have fun with food. At the population level, some proportion of people some of the time will find themselves wanting that food, wanting that cola, and taking it. At the population level, some proportion of people get more calories than they otherwise would. And some proportion of them get fat.

It’s important to remember that getting fat, being a biological process, is not a simple matter of balancing calories in and calories used. Nothing in biology is simple. Calories in is a factor, certainly. If it wasn’t, you’d see fat people among famine sufferers.

But how the body stores fat stands right between the two halves of the equation. That is a complicated, hormonally controlled process we’re only beginning to understand. Insulin is one of those hormones, but only one. Sex hormones are also among the messengers that carry out the regulation. The starkest example of fat storage gone crazy is rare genetic conditions where the body’s hormones that promote fat storage are so active, they don’t leave enough glucose circulating in the blood for metabolic needs. Everything goes into fat, there’s too little left over for the business of staying alive, and the person is literally starving while putting on weight.

A big contribution of Ebbeling’s and her colleagues’ research is demonstrating the subtle effect of fat storage regulation that’s within the normal range. And since hormones are part of that process, hormone disruption can be expected to have a huge effect on fat deposition.

Which brings me to the second big environmental factor: a whole group of chemicals. They’re called hormone disruptors and they come from some plastics, pesticides, hormonal medicines, and so on. Those break down into hormone analogues and get into the environment. As I said in an earlier post on the Obesity Epidemic, if hormones help regulate energy balance, and if we’ve flooded the environment with bad substitutes for hormones, is it any wonder that people are having trouble regulating energy balance?

So, you may be asking, what does it all mean? What are we supposed to do about it? I’ve said it before so I’ll just say it again:

Like all public health issues, nothing less than a population-level approach will work. Dysentery, cholera, and typhoid are never wiped out by drinking boiled water. They’re wiped out by building municipal sewers. Smallpox wasn’t eradicated by avoiding smallpox patients. It was eradicated by universal vaccination. The individual actions aren’t useless. They just don’t change the widespread causes of the widespread problem.

Modern health problems like cancer and obesity aren’t going to be wiped out by eating fresh vegetables. Eating veggies is good, but it doesn’t address the basic problem. That’s going to take nothing less than a change to clean sustainable industry.

It’s almost enough to make you wish a mere diet really was all that’s needed.