Why are we fat when our ancestors were thin?

Dr. Mehmet Oz, MD
Cardiology (Cardiovascular Disease)
The most common question heard among overweight people isn't: "Can I have more sour cream?" It's: "Why can't I lose weight?" While you may think you know the answer (i.e. severe pancake addiction), the real reason is biological.

Our ancestors survived by gaining and storing weight to survive periodic famines. That has left our bodies to store fat and gain weight, tendencies that willpower alone can rarely overcome. To see how our bodies have morphed from rock-hard to sponge-soft, let's look inside the bodies of early man and woman. They looked like stereotypical superheroes—strong, lean, muscular, able to jump snorting mammals in a single bound.

They consumed their sugars through fruit, and they even splurged when they came across the Paleolithic Cinnabon—a honeycomb. The difference between their splurges and ours? They came across the sweet treats only rarely. Also, it was a lot of work to get food, so they naturally burned many of the calories they consumed through the physical activity of hunting and gathering.

Because salt and sugar were scarce elements, our ancestors mostly feasted on grains, vegetables, and meats—for good reason. The meat provided the protein, vitamins, minerals, and fatty acids that helped them grow taller and develop larger brains, while the other foods gave them nutrients such as glucose, found in fruit and the complex carbohydrates of plants, that they needed to grow and develop, and for energy to move. And, of course, food was always fresh, as there was no canning or refrigeration to store up food for Super Bowl parties, or sneak in an 11 p.m. bowl of sugar-coated reindeer oats.

Another difference was that the meat our ancestors ate wasn't like the meat we know today. Theirs was low in fat and high in protein; ours often comes in the form of corn-fed cows pumped up to make fattier, tastier cuts. Even today's buffalo burger is corn-fed. Truly wild game has about 4-percent fat, while now most commercially available beef has nine times that amount.

The result: Your tribal forefathers and foremothers could eat anytime they could harvest or catch something—and still not put on excess weight.

The lesson: Our ancestors never thought about a diet in the way we do—and their bodies had the approximate density of granite. Us? We obsess about diet more than red-carpet reporters obsess about designer dresses, and our bodies have the consistency of yogurt.
YOU: On A Diet Revised Edition: The Owner's Manual for Waist Management

More About this Book

YOU: On A Diet Revised Edition: The Owner's Manual for Waist Management

For the first time in our history, scientists are uncovering astounding medical evidence about dieting -- and why so many of us struggle with our weight and the size of our waists. Now researchers...

Continue Learning about Obesity

How to Outsmart Your Obesity Genes
How to Outsmart Your Obesity Genes
Not a lot of size 6's in your family? Well, then, here's the simple trick to outrunning your obesity genes: movement. In a study of people geneticall...
Read More
Can a person with obesity be considered healthy?
Dr. Mehmet Oz, MDDr. Mehmet Oz, MD
New research suggests that even if you feel like you’re perfectly healthy, obesity can be wreaking h...
More Answers
How is morbid obesity treated surgically?
Dr. Nicole A. Florence, MDDr. Nicole A. Florence, MD
When a person has a substantial amount of excess body weight, as well as complications from their ob...
More Answers
What Diseases Do You Worry About?
What Diseases Do You Worry About?

Important: This content reflects information from various individuals and organizations and may offer alternative or opposing points of view. It should not be used for medical advice, diagnosis or treatment. As always, you should consult with your healthcare provider about your specific health needs.