Bacon, burgers and butter are delicious but unhealthy. At least, that's the conventional wisdom.
Saturated fat has been linked to higher levels of blood cholesterol and an increased risk for heart disease and stroke.
That thinking "has been the centerpiece of our dietary wisdom for over 50 years … and it really goes back to some very weak science that was done in the 1950s and onward," Teicholz said. "But it really- when you go back and look into the science, it really has been shown not to be true."
Current guidelines from the U.S. Department of Agriculture show a recommended daily "food budget" split between grains, vegetables, fruits and proteins, with limited dairy consumption and allowances for so-called healthy, unsaturated fat.
Teicholz disputes the common belief about saturated fat.
"It's not unhealthy," she said. "Also it's a solid fat you can see … it's not an oil. And that means that it's far more stable."
But some nutritionists - including Rachel Beller, a nutritionist and the author of "Eat to Lose, Eat to Win" - aren't convinced.
"I think having too much saturated fat could potentially raise numerous risk factors for our health," she said.
Teicholz says the real culprit behind heart disease and weight gain is the nation's addiction to carbohydrates and sugar.
Teicholz described her typical day's diet.
"So I start my day with bacon," she said, adding that she usually snacks on nuts, cheese and salami for lunch.
"I tried so hard when I was a vegetarian … And I used to obsess about food. But now I just don't. And I barely exercise," she said. "I found that I lost 10 pounds … And my cholesterol levels were fine."