Do Fatty Foods Make You Fat?

In a study published last year, a team of Boston-area researchers studied the eating habits of more than 18,000 women to better understand the relationship between high-fat diets and obesity.

The study, published in The American Journal of Clinical Nutrition, compared women who ate high-fat dairy with those who consumed dairy with reduced fat.

If you guessed that the high-fat consumers were more overweight you’re mistaken. In fact, women who ate higher fat dairy were less likely to put on weight than those who ate lower fat.

But this is just one study. So let’s also look at a survey of research study published in 2012. It surveyed 16 studies and came to the same conclusion. In 11 of those studies, people who ate less whole-fat dairy were more likely to be overweight.

The evidence that we need to be less worried about fat has been laid out in excellent reporting in books by Gary Taubes (Good Calories, Bad Calories) and Nina Teicholz (The Big Fat Surprise). These authors point out that the rise in North American obesity rates coincided with a shift in eating habits away from diets high in proteins and fats (think bacon and eggs) towards diets high in carbohydrates (think sugary, processed breakfast cereal).

The evidence is compelling that we need to be less worried about reducing fats in our diets and more focused on reducing sugars and processed carbohydrates.

But most of us don’t believe it, as evidenced by our shopping habits. Most of us will choose a low-fat, high-sugar yogurt over a high-fat, low-sugar variety.

Why? Partly because we use the same word — fat — for a micro-nutrient in food and for a roundly-shaped human body.Β And then there’s the well-established fact that a gram of fat contains more calories than a gram of protein or a gram of carbohydrate.

But that doesn’t mean we process the calories in the same way.

In her excellent 2013 blog post, Margaret Floyd explains why fat does not trigger the hormones that create fat storage the way sugar and carbs do.

When you eat something sweet, your blood sugar levels increase too quickly, and your pancreas secretes the hormone insulin to take the excess sugar out of your blood. Insulin is a fat storage hormone. It stores that extra sugar first as glycogen, and then as triglycerides (fat) once glycogen stores are full.

Consuming fat with sugar actually slows down the sugar spike, Floyd writes, which explains why you can pack on more pounds from lower-fat desserts.

Not only that, but fats satiate you in a way sugars never will.

…[E]ating fat makes you fuller sooner and longer. Eating sugar leads to a sugar crash which makes you hungrier sooner and in a position to crave more sugar. A vicious cycle indeed.

The bottom line, Floyd notes, is that eating fat doesn’t make you fat. Eating sugar makes you fat.

So does this mean it’s okay to gorge on Ben and Jerry’s and double-creme brie? No — eating right is all about moderation.

Instead, it means you need to pay less attention to the fat content and more to the sugar and carbohydrate content in your foods. And it means that the low-fat, high-sugar chocolate milk they sell in your kid’s school cafeteria is probably worse for them than whole-fat unsweetened milk they refuse to sell.

How do you think of fat in your diet? Good, bad, or indifferent?



  1. Popped over from the Community Pool to say Hi. Looks like you’ve got some really interesting articles here. Last year I had chemo-therapy for chronic leukemia (CLL) so I feel like I have a new lease on life, too. Now, if only I had the energy to go with it. πŸ™‚

    I see one problem here: No “Follow this blog” button. πŸ™ Since you have all those tech smarts I won’t explain how to install one — but you should definitely have one. Right now I’m not sure how a reader could follow your blog if he/she wanted to.

    Anyway, happy blogging.

    • Thanks so much Christine! I have added back the follow this blog button. I didn’t realize I lost it when I changed my template. I will also get better at categories and tags, as you suggested on my other blog.

  2. This is such an important message everyone should hear. Sugar messes up our entire body and it is shocking how much we find of it most processed food. Loved your referencing as well, great read!

    • I don’t think I’m capable of cutting sugar out of my diet altogether, but definitely trying to think of it more of a treat than a regular food group.

  3. I have heard more and more evidence coming out about this recently; I even heard one expert say “believing that eating fat makes you fat is like believing that eating green foods makes you green” but the message isn’t widespread enough yet. This is a great easy-to-read and informative summary that will hopefully make some people look more carefully at their views on nutrition.

    • Thanks for this. You’re comment about green foods inspired today’s blog post!

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