Why Sugar Makes Us Fat

“Eat less sugar.” We all know this basic guideline, as sugar has become Public Enemy Number One in our nation’s health problems. And yet, while that sounds simple on paper, cutting sugar out of our diets is tough. When the low-fat craze hit in the 1980s, manufacturers simply replaced the fat products with sugar. As a direct result, we’ve been steadily gaining weight as a nation, and finding it harder and harder to avoid sugar. Unfortunately, the simple truth is that sugar makes you fat, and here’s why.

What is a Sugar?

Sugar is the simplest form of carbohydrate, a type of organic molecule occurring in many foods. There are three varieties—glucose, fructose, and lactose. Table sugar (“sucrose”) and high fructose corn syrup are both nearly 50-50 mixes of glucose and fructose. The sugar found in fruits is primarily fructose, and lactose is found in dairy.

Other simple forms of carbohydrates, like the white flour used in most processed foods, are very quickly broken down in your stomach into glucose. In terms of your body’s response, there is very little difference between a handful of pretzels and a spoonful of sugar.

Insulin Response

Whatever the source, all sugars are converted to glucose and enter your bloodstream in that form. Glucose is often cited as your body’s preferred energy source because it’s so readily available, and can convert quickly into energy. Your brain does require glucose to function, as do all the other cells in your body.

However, your immediate-use fuel tank is very limited, and any excess glucose floating around in your bloodstream after your immediate needs are filled are put into your long-term primary storage facility—also known as your fat.

Before you even swallow a bite of sugar or other simple carbs, your brain begins preparations to process the sugars you are consuming. Enzymes in your stomach break it down into pure glucose, and it is released into your bloodstream. When the amount of sugar in your blood rises, insulin is released.

Insulin’s job is complex, but one of its main functions is to take any sugar that your body can’t immediately use—which will be most of it—and put it into your fat storage. The higher the dose of sugar or other simple carbohydrates, the more insulin is released and the more energy will be stored into fat. As you continuously eat high-sugar foods, insulin is continually present in your blood and is continually adding to your fat storage.

After all the sugar is stored away, insulin still remains. The higher the sugar burst, the higher the insulin spike and the more insulin remains after processing. Insulin wants a job to do, so the lingering excess causes you to become hungry again within a very short time, usually craving more sugar, so the insulin can be put to use. This is why you often feel hungrier after you eat a high-carb meal or dessert.

What’s even worse is that insulin inhibits your body’s ability to release stored fat. This means that even if you’re limiting your calories, eating a diet high in carbohydrates will thwart your efforts to lose body fat. If insulin is present, you won’t burn fat.

Even worse than making you deal with stubborn body fat, continuously high levels of insulin in the body can lead to type 2 diabetes. Type 2 diabetes occurs when the cells become resistant to the insulin present. Therefore, the body needs to release even more insulin, and an even higher percentage of the blood sugar is stored into the fat.

To summarize: Eating sugar or simple carbs releases insulin proportional to how much you ate. Insulin puts the sugar into your fat storage, and makes sure no fat leaves storage. High levels of insulin over time can lead to type 2 diabetes.

Carbs and Weight Loss

The reason why low-carb diets work is that consuming fewer carbs allows your insulin levels to stay low. When insulin levels are low, your fat stores are not being built up, and you can even mobilize fat OUT of long-term storage. The added benefit is that when your blood sugar levels are kept even, you experience far less hunger and cravings, making it much easier to stick to your goals.

Certain extreme low-carb diets, such as Atkins, have left a dark stain on our collective understanding of “low carb”. The typical American diet is around 60% carbohydrate or more. Reducing that percentage can make a big difference in terms of weight loss.

But take note! As you reduce the percentage of carbohydrates, you will have a higher percentage of calories from fat. This is okay. Despite decades of being told fat is bad, current research has found unequivocally that consuming fats does not make you fat.

It may seem odd to replace the foods we typically think of as healthy, like whole grain breads and brown rice, with high-fat foods we’ve been taught to stay away from, like full-fat salad dressings and butter. But the only way to lose weight is to keep your carb intake low enough to keep your insulin low enough to allow the fat to be mobilized outward.

How low your carbohydrate consumption needs to be to allow that to happen depends on many factors, such as your current level of insulin resistance, weight, and genetic factors. Some people may be able to lose with only a minimal of carb cutting, others may need more severe cuts.

Good Carbs

As aforementioned, you brain and body does require glucose, and it is an important energy source. But you do not need to consume glucose to feed your brain; your body is highly skilled at creating the glucose it needs from more complex carbs, and even from fat. Sugar and processed grains are very small molecules, broken down into pure glucose nearly instantly.

This means that the sugar enters your bloodstream very quickly, and insulin spikes rapidly in response. However, carbohydrates are also present in fruits, vegetables, and dairy, in a much more complex form. This means the carbohydrate molecule is much larger and requires more time to break down and digest. Ultimately they do break all the way down to glucose, but this takes time and therefore the sugars enter your bloodstream much more slowly, meaning a much smaller dose of insulin will be released in response.

To use a metaphor, when you eat sugar and white flour, your insulin reacts like the scariest roller coaster at the amusement park: up fast, down hard, over and over. You get off feeling a bit dazed and shaky. Eating complex carbs is more like the little kiddie track rides, gently rolling along with a few little bumps. It’s an easy ride and you walk away feeling comfortable and stable.

If you’re trying to lose body fat, your best bet is to avoid sugar and simple carbs. If you need something less drastic, you can help even out the insulin response with food pairing. Fats, proteins and fiber digest very slowly.

Therefore, if you can’t give up your pasta, scale back on the amount of noodles and make sure to pair it with some good fats, protein, and fiber, like olive oil, chicken, and veggies. If pretzels and crackers are your go-to afternoon snack, scale back your portions of those and add in some hummus or guacamole to slow the digestion, increase fullness, and slow the release of insulin.

Our bodies are designed to love simple sugars. Thousands of years ago, when food was scarce, it was in our best interests to load up as much as possible on these things, which would be stored as fat to be used in lean times.

Unfortunately, now they are available at all times, and we never experience a famine period to use up that stored fat. Our sugar-loving bodies haven’t evolved much, but our understanding of how our bodies work has. Hopefully a little understanding of how sugar and other simple carbs affect you can help you chose to cut back, for the sake of your health.

Nourishing Thoughts is written by Julie Miller, an expert on nutrition and fitness instructor at the C.W. Avery Family YMCA.