The diet advice you should never follow

As you enjoy your Thanksgiving left-overs, let’s continue with the saturated fat story that I began to tell you about in yesterday’s Dispatch

We now know that eating some saturated fat actually protects you against cardiovascular disease. And avoiding it may do more harm than good.

Sure, fat does have a high energy content per gram–about 9 kcals per gram. Carbs and protein, on the other hand, have about 4 kcals per gram. This means that it takes more energy to burn off fat compared to carbs or protein. But burning calories in a test tube does not equate to human metabolism. And the body metabolizes fat very differently than carbs. Or even protein.

In fact, for many years, the biochemist Richard Feinman and nuclear physicist Eugene Fine have researched thermodynamics and metabolism. Their research demonstrates that the body metabolizes different macronutrients in different ways. That is, it treats fats differently from carbs metabolically.

Back in 1956, one of the earliest studies on obesity turned up some interesting evidence about fat metabolism. In this study, researchers compared patients who consumed three different types of diets. The first group followed diets that consisted of 90 percent fat. The second group consumed diets with 90 percent protein. And the third consumed 90 percent carbohydrates.

The researchers found that the high-fat group experienced the greatest weight loss. They concluded that the macronutrient composition of the patients’ overall diet outweighed, so-to-speak, the intake of calories.

A much more recent study published in the Journal of the American Medical Association found that a low-fat diet results in the greatest decrease  in burning calories. In other words, following a low-fat diet slows down your calorie-burning engine. Limiting fat also results in unhealthy blood lipid patterns and increases in insulin resistance, compared to a low-carb diet.

Of course, low-carb diet gurus claimed to suddenly “discover” these facts in the 1980s and 1990s. But the science actually dates back to the 1950s. And some of the most practical, helpful medical advice dates back to the turn of the century.

Yet despite these diet gurus’ advice, Americans today eat less fat than ever. In fact, overall dietary consumption of fat has dropped from 40 percent of calories to just 30 percent over the past decade. Yet over this same period, obesity has skyrocketed to become the latest sanctioned “disease.”

Despite these facts, the mainstream medical establishment just can’t seem accept the idea that we need fat to survive. And it’s not just about keeping the weight off. As I explained yesterday, eating some saturated fat gives us valuable nutrients.

Of course, as an anthropologist, I take the long view of human eating patterns. And for millions of years, eating fats helped humans survive and evolve. So, today the taste and texture of fats appeals to us. In other words, we always needed fats to survive, so they taste good to us!

Of course, sugar tastes good too. So, when the government began to demonize saturated fat, the food industry cleverly learned to replace it with sugar. And for decades, the government and health experts alike told us that sugar is safe, except for its contribution of excess calories.

Now we know better.

Like fat, sugar is hard to find in Nature. But experts now recognize sugar as an independent risk factor for metabolic syndrome, high blood pressure, high blood sugar, high triglycerides, low HDL cholesterol, and increased waist circumference. And it’s not just about the calories.

So this holiday season, keep it simple. Enjoy the dark meat. And a little butter on your yams. But avoid the bread. And skip the extra trips to the dessert table. Moderation is the key.


1. “Calorie intake in relation to body-weight changes in the obese,” Lancet, July 28, 1956

2. “Effects of dietary composition on energy expenditure during weight-loss maintenance,” JAMA 2012;307(24):2627-34