Back to Fitness: How Sugar Is Making Us Fat


One of the main reasons we adults exercise is to keep trim or lose weight. It seems the natural progression of life is for it to be easier and easier to gain fat as we get older! With the ever-increasing busyness of life, how can we find time for exercise?

The truth is, exercise has nothing to do with your weight. It’s all about your diet. Okay, exercise is of course helpful. However, go to any marathon or even ultramarathon and you will clearly see that exercise alone is not a recipe for weight loss.

If you want to lose weight, whether a little or a lot, you’ve got to cut sugar and simple carbohydrates out of your diet. One more time: If you want to lose weight, you’ve got to cut sugar and simple carbohydrates out of your diet.

A long time ago, we all thought fat is bad. The fats we eat would naturally turn into fat in our belly, right? Meanwhile, sugar snuck under the radar as nothing more than a harmless sweetener.

Fortunately, smart doctors and researchers out there are always questioning formerly held truths. And good research over the past decade shows us one very important fact: sugar makes us fat.

That’s right: fat doesn’t make us fat, sugar makes us fat.

What happens when we eat sugar? Note that when we talk about sugar, we’re talking about all forms of sugar as well as simple carbohydrates such as breads, pasta, and potatoes. Once these foods are broken down in our gut they are presented to our body the same as simple sugar.

When we eat a meal with sugar, our blood sugar starts to rise, which causes our pancreas to release a large amount of insulin. Insulin’s main job is to control blood sugar levels, to bring them back down to normal. So where does all that blood sugar go? When you’re active, it goes to the muscles and tissues that need some energy, but with a sugary meal or a high-carbohydrate meal, much of that blood sugar goes right into fat storage! That’s right, insulin causes the sugar we eat to go right into fat storage, increasing our waistline. But that’s not all insulin does.

Insulin also blocks our body’s tendency to burn fat for energy—a double whammy.

And new research has demonstrated one of the most important findings in obesity research: insulin blocks a hormone called leptin. Leptin is a hormone produced from our fat cells that tells our brains “I’m full.” So with that sugary/carb-rich meal, not only has a lot of that sugar turned into belly fat, but now it’s causing us to feel more hungry, all the while having less energy as our blood sugar levels drop back down.

Thus begins the vicious cycle that is not genetically driven, but rather hormonally driven. We eat sugar, so we gain fat, so we feel hungrier, so we eat more sugar, so we gain more fat, and on and on.

Sugar consumption is also associated with higher levels of inflammation in our bodies, which increases our risk for a slew of diseases including heart disease.

Unfortunately, sugar and simple carbs are everywhere. Most of the processed foods (anything in a box or package) you purchase have sugar added to them. And to make things more complex, most of the “health” foods and “weight loss” foods are loaded with sugar! These “fake healthy” foods advertise things like “high protein,” “high fiber,” “fat free,” and “whole grain,” when in reality they are sweetened with sugar, leaving your waistline bigger.

If you’re looking for a “diet” to follow, don’t make it complicated by following one that you have to read a book to understand. Just avoid sugar and simple carbohydrates. Here are some practical tips:

• Never drink soda, juice, sweet tea, or even diet sodas. Ever. Just stop today. Purchase a nice Nalgene water bottle, decorate it with some stickers and start drinking water. Of course it’s not as delicious as a soda, but after a week, you’ll wonder how you ever drank those before.

• Eat whole foods! Eat vegetables, salad, sweet potatoes, nuts, beans, and fruits! Yes, there’s sugar in fruit, but not a lot and it’s loaded with fiber and other nutrients to help slow insulin release.

• Avoid/limit breads and cereals. Even whole wheat breads are a big culprit of insulin spikes. For weight loss, you are better off eating eggs and bacon for breakfast than a bowl of whole grain cereal. When you do eat simple carbs, be sure to also eat a lot of fruits and vegetables at the same meal so their fiber can help slow insulin release.

• Avoid “fat-free” and “low-fat” foods. They are usually loaded with sugar. Dietary fat intake is not associated with body fat content.

• Try a two-week “sugar detox.” Zero sugars for two weeks. Check all labels. You’ll be amazed what a difference it makes and how much better you’ll eat if you simply avoid foods with sugar in the ingredient list!

For some people, cutting out sugar seems impossible or even sacreligious, especially around the holidays. But folks, you’ve only got one life to live, and it’s this one. Why not get the most of it? Don’t settle for moderation, go for excellence!

To understand sugar’s effects better, I strongly encourage you to watch “The skinny on obesity” video series on YouTube with Dr. Robert Lustig from the University of California-San Francisco. It is eye opening and incredibly informative on the above topic. Some helpful books are Pure, White, and Deadly: Why Sugar Is Killing Us and What We Can Do to Stop It by John Yudkin, Wheat Belly by Dr. William Davis, and Fat Chance by Dr. Robert Lustig.


  1. I would LOVE to share this article with my patients! It pulls together many of the pieces I discuss in our visits. Do I need official permission to photocopy all or parts of this article?

    • Hi Erin,
      Feel free to share copies, just be sure to include the author and source! Thanks for asking.

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