CHAPTER 3
Not all Fats are Equal
PART 1
Meet the Fats Family
The fats are big, sprawling clan, with lots of aunts, uncles, cousins, heroes and villains and a few that claim to be misunderstood. And yet, there are strong family ties and shared resemblances. A better understanding of all branches of the fats family tree can make a profound difference to the health of your own family.
Family Chemistry
What the members of the fats family have in common is a basic chemical structure: a chain of carbon atoms bonded to hydrogen atoms. (It may help to visualize something like a set of TinkerToys and then imagine simple chains of balls and sticks.) One basic way in which fats differ is the length of their carbon backbones. The major dietary fats begin at 8 carbon atoms long and go to up to 22 carbons in length. READ MORE
The other basic way in which fats differ is the number of hydrogen atoms that are bound to the carbon chain. A carbon chain that has only single bonds to other carbon atoms is one that is attached to as many hydrogen atoms as possible. These fat molecules are called saturated (the hydrogen saturates all the available carbon atoms). Fat molecules that have double bonds between one or more carbon atoms are called unsaturated (meaning they have less than the maximum possible attached hydrogen atoms). Unsaturated fats with one double bond are called mono-unsaturated fats. Unsaturated fats with two or more double bonds are called poly-unsaturated fats.
The significance of the chemistry is that the length of the carbon chains and the number of double bonds determine how the body is able to use these building blocks. Let’s go back to building materials. Think short i-beams, long i-beams, i-beams bent to the left, i-beams bent to the right, and so on.
So what we refer to as fat in our diet is actually a large group. The fat on a piece of steak, the butter on a roll and the oil in salad dressing are all related, but each has different chemical properties that translate into different roles and functions in the cells and tissues of our bodies. LESS
PART 2
Where’s the Fat At?
There is fat in virtually every food from bananas to bacon. It varies dramatically in amount and it also varies in type of fat. What’s more, in nearly all of the foods we eat, whether it is a burger, glass of milk, avocado, almond or sardine, we are eating a mixture of fats, both “good” and “bad.” READ MORE
A stick of butter, for example, contains 60% saturated fat, 25% mono-unsaturated fat, 5% poly-unsaturated fat. For beef fat the numbers are 39%, 44%, and 3% (both butter and beef fat contain naturally occurring trans fats). Olive oil has 13% saturated fat, 72% mono-unsaturated fat and 8% poly-unsaturated fat, while sunflower oil is 10%, 20% and 66%.
What counts most is which fats predominate in the food. So while you might be better off cooking with beef fat rather than with butter in terms of saturated fats, you wouldn’t choose either of them for their relatively small amounts of healthy poly-unsaturated fats. Instead you would pick a vegetable oil like olive or sunflower, with high levels of total unsaturated fats. LESS
PART 3
How Much Fat is Too Much?
All human diets contain fat. In some Asian countries fat can constitute as little as 10% of total calories consumed. Fat consumption in some European countries is as much as 45% of daily calories. In the U.S. the percentage of fat we consume is dropping, from more than 40% a few decades ago to 34% more recently. But many experts believe that statistic is a bit misleading, since over the same time period, total calories consumed by Americans have increased significantly. Total fat intake, measured in grams, has changed very little. READ MOREHow much fat do the experts think we should have? The Institute of Medicine has arrived at a range they refer to as the Acceptable Macronutrient Distribution Range (AMDR). And for fats, this is estimated to be 30-40% of total daily calories for children ages 1 through 3. For older kids and adults, it is 20-35% of total daily calories.
But how much of each fat should account for those percentages? That’s a trickier (and more important) question. Our bodies can make all the saturated fat we need all by ourselves! That would seem to suggest that we don’t need any dietary sources of those fats and that we should eliminate them all. Well, the experts don’t go that far. What many will recommend is that saturated fats not exceed 10% of total calories (some experts suggest 5% would be a healthier target).
To reduce saturated fats to 0% would be essentially impossible. As we saw in the above examples, even healthy oils contain low levels of saturated fat. And even trying to minimize saturated fats to less than 5% would make it extremely difficult for most people to maintain healthy levels of protein and micronutrients in their diet. LESS
PART 4
Striking a Balance
Yes, it can be maddening that fats in our diet seem so complicated. But as we will see, there are some basic guidelines for eating more of the good fats and less of the bad fats that are both simple and effective. READ MOREA big part of the dietary dilemma, says Dr. David Katz, is that people found it easy to believe that either fats were all bad or carbs were all bad. And that is simply not true. “Not all fats are created equal. And that goes for carbs too. An either/or approach to dietary macronutrients does not reflect our true knowledge of nutrition and the true capacity of using food to improve both health and weight.” We know that living on fat-free Snackwell cookies wasn’t the answer and we also know that neither is living on bacon cheeseburgers. “The latest diet news always seems a tempting morsel,” cautions Katz; “ingest at your own risk.” LESS