When I learned that Nina Teicholz had written a book entitled The Big Fat Surprise: Why Butter, Meat & Cheese Belong in a Healthy Diet, I knew I had to read it immediately. I’m only partway through it, but it has already changed the way I look at the world of nutrition science.

A central idea in the book is that the nutrition science and medical communities accepted, without sufficient evidence, the premise that dietary cholesterol and saturated fat are the cause of heart disease in people. This occurred largely due to one particularly charismatic (some might consider him to be more of a bully than a charismatic thought leader) nutritionist who cherry-picked data.

So, in the 1980s and 1990s especially — until Robert Atkins came along and shook things up with his diet — cholesterol and saturated fat were considered enemies of the human race. Consumption of red meat and eggs dropped. Grocery store items proudly proclaimed to be cholesterol free. People adopted low fat or ultra low-fat diets.

And, during the 1980s and 1990s (and continuing on through today) obesity was an ever-growing problem. With skyrocketing obesity rates came epidemics of diabetes and other significant human morbidities. Heart disease remained (and remains) the No. 1 cause of death for Americans.

I’m looking forward to the conclusion of the book. Will Teicholz jump on the Atkins bandwagon and claim that carbohydrates are the bad guys? Or will she come to the conclusion that a balanced diet, such as was recommended before the anti-cholesterol and anti-saturated fat crusades, is the way to go? And what does this have to do with dogs?

Ms. Teicholz’s final conclusions, in my opinion, will be largely irrelevant. I will take them with several grains of salt. My takeaway message from the book is that the human body is magnificently complex. Science has so far only scratched the surface with its understanding of physiology and biochemistry, and these two fields are the basis of nutrition. There are nuances that we simply don’t yet understand. Nutrition science is a nascent field with a long way to go. In other words: Nobody knows what is the ideal diet for a human.

And here’s what this has to do with dogs: They, like us, are advanced mammals. Their physiology and biochemistry is no less complex than ours. And that means that, at this time, nobody knows what is the ideal diet for a dog.

That doesn’t mean there aren’t plenty of people who think they know what is ideal. And goodness knows some of them like to make noise on the Internet. Some of these folks espouse theories that seem logical and sensible. But they’re not yet proven.

Let’s take the major pet food manufacturers, for example. A major complaint against them is that their diets are loaded with carbohydrates. The pet food manufacturers point out a basic fact of physiology: The body can convert fats, carbohydrates, and proteins into each other. Once those carbs are in the body, they can be converted to protein or to fat, as needed. There are certain vital nutrients that cannot be synthesized by the body; these must be present in the diet. There is, in theory, a great deal of flexibility with the rest of the ingredients.

Some of the major pet food manufacturers have research facilities where they have fed dogs nothing but their brand of commercial food for many generations. These groups of dogs are alive, well, and healthy with no nutritional deficits. This is taken to mean that the diets are complete and balanced.

And indeed, from a scientific standpoint, it is hard to refute the claim that a diet fed exclusively to many generations of dogs must be complete and balanced. But that doesn’t mean it’s ideal. There almost certainly could be some way to make the diets better.

How about the folks who advocate grain-free or raw diets? They often claim that such diets are more species appropriate, since wild canids usually limit their grain intake to that which is found in the gastrointestinal tracts of their prey. In theory, this makes sense. But the theory’s not proven, and it also neglects the fact that dogs are no longer wild canids. They co-evolved with humans, and as we started eating grain, no doubt so did they. (Developing countries currently offer a pretty good idea of what the canine ancestral environment looked like, and in those places dogs eat human leftovers and refuse. In those places, dogs eat what humans eat.)

When I was a young man in the 1990s, I thoroughly bought into the mantra that humans should eat diets low in fat and cholesterol. I studiously avoided red meat and eggs. I ordered sandwiches without mayonnaise, and I ate my toast without butter. I was in great health.

Since that time I have relaxed my diet substantially. I love steak, and I eat it. I love bacon and eggs, and my breakfast habits reflect that fact. I order sandwiches with extra mayo. I remain in great health.

Here’s the point: I came to no harm from following the low fat fad of the ’90s. I missed out on a lot of good meals, but I came to no bodily harm. Now that the nutritional pendulum has swung in the other direction, I’m still in great health. And I won’t be surprised if the pendulum swings back, or if it changes course altogether.

My body, like all human bodies, can thrive on a diversity of diets. I have no idea what the ideal diet is, but so far in my life, as long as I have consumed food in moderation and engaged in plenty of exercise, I have not suffered from any nutritionally mediated problems.

Canine bodies are equally versatile. I know an awful lot of healthy dogs. I know dogs who are thriving and in perfect health on commercial diets. I know dogs who are thriving and in perfect health on grain-free or raw diets. I know dogs who are thriving and in perfect health on homemade diets.

Is one of these diets the ideal one? Is there even such a thing as an ideal diet? Despite all of the hype and the noise, nobody knows. Nothing is proven.

However, in the next 15 years or so we may learn a great deal about this subject. The currently running, massive lifetime Golden Retriever study will be monitoring the health of a huge group of dogs fed different diets. By the end of the study we may know which diet is ideal, or we may learn that there is no such thing as an ideal diet. Or, let’s face it, we may simply learn that we don’t know much at all.

What do you feed your dog? Tell us in the comments!

Read more on what to feed your dog:

• Let’s Talk: Do You Insist on Feeding Your Dog “Premium” Dog Food?
• Ask a Vet: How Much Should I Feed My Dog?
• How to Choose a Healthy Dog Food
• Wet or Dry Dog Food?
• 5 Reasons to Throw Away Your Dog’s Food Bowl
• Let’s Talk: What Is the Strangest Food Your Dog Likes to Eat?
• Eight Ways to Deal with a Finicky Eater
• The Importance of Dog Nutrition
• My Dog Eats Too Fast. Here’s How I Slow Her Down

Learn more about dogs with Dogster:

• Why Do Dogs Lick People?
• 6 Ways to Thwart an Off-Leash Dog Rushing You and Your Dog
• I Worked at a Large Commercial Pet Store, And What they Do to Puppies Will Shock You

Got a question for Dr. Barchas? Ask our vet in the comments below and you might be featured in an upcoming column. (Note that if you have an emergency situation, please see your own vet immediately!)