Today’s anti-carb diet hype is really giving carbohydrates a bad name when, actually, the right type of carbs form the backbone of good nutrition.

Sadly, the average American eats way too much of the wrong type—those sugars and processed starches in snack foods, most bakery goods, beverages and desserts—and not enough of the high-nutrient carbohydrates we find in vegetables, dairy and whole grains, which provide most of our essential vitamins and minerals. But the current hype villainizes the good with the bad. This is why you need to know your macronutrients.

If you’re really curious about the diet industry’s latest creations, you can blow your money on the new no-carb, low-carb products. But if what you want is to eat better and maybe even lose a few pounds, a little understanding about macronutrients will serve you better.

Carb Structure and Function

Chemically, all carbs are made up of sugar units. Nearly all carbohydrates come from plant sources, but they also occur in dairy products, honey and some seafood.

They are typically classed as “complex” carbs, which include starches and fiber, and “simple” carbs, which include sugars and starches that have been commercially processed to the point that they’ve almost been broken down into sugars already.

Simple carbs contain just one or two sugar units and they taste sweet; they’re rapidly processed by your body and they provide energy (calories), but no nutrient value.

Complex carbs contain long chains of sugar units. They have a characteristically starchy taste, and unlike sugars, they are typically found in foods rich in vitamins, minerals and fiber—like vegetables, whole grains, dairy foods, and even some protein. Because of these additional nutrients, the body takes a longer time to digest them than it does simple carbs.

When you digest carbohydrates, they are all broken down into simple sugars, which are converted in the liver to one common denominator: glucose. Also known as blood sugar, glucose is the body’s basic fuel.

The main function of carbohydrate in the diet is to supply the body a ready source of fuel for glucose production. The trick is to determine how much is really needed for that “ready source,” based on how much energy you burn up, because excess glucose that is not immediately needed for energy is converted to glycogen or fat.

Glycogen, a starch made by your body, is stored in the liver and muscle for the body to draw on as a secondary quick energy source. An average 150-pound man can store about 1750 calories this way, but that’s about it.

When glycogen stores are full, any leftover glucose is then changed to fat, and unfortunately, there is no limit to the amount of fat that can be stored.

Simple Carb Complications

Recent research shows that some Americans get up to half of their calories today from simple carbohydrates.

But eaten alone—as in a breakfast of toast and juice, or a snack of pretzels and a soda—those simple carbs will cause the blood sugar to rise dramatically. This in turn causes a spike in the production of insulin, the hormone that carries glucose into the body’s cells.

Since the cells can only take so much glucose at once, insulin also aids the conversion of the excess glucose into fat, so it can be stored. Because of this, people who eat a lot of simple carbs have typically higher insulin levels, and produce and store fat more quickly and efficiently.

And there’s more bad news. Another side effect of that spike in blood sugar and insulin is the inevitable crash that follows. Once insulin is on the job, it makes quick work of cramming the glucose from simple carbs into your body’s cells.

But as that task is suddenly finished, you experience an abrupt drop in blood sugar that can be accompanied by shaking, dizziness and ravenous hunger—even though you’ve actually eaten quite recently.

And if you’re one of those people prone to eat simple carbs, you’ll probably grab for more of the same. See the vicious cycle developing there? You could be on that roller coaster all day, and indeed, many Americans are, without even knowing it.

For instance, your customary sourdough English muffin and glass of juice may be a quick breakfast, but it’s also a spike-and-crash recipe, because the white flour in that muffin is already so processed it’s nearly a sugar already.

The same is true for your fruit juice. While it may have the same nutrient value as the whole fruit in terms of vitamins, without the fiber, that juice is basically liquid sugar pouring into your blood stream.

Now, if you make that a whole-grain muffin and a solid piece of fruit, or couple it with a glass of skim milk, that’s another story. The extra nutrients and fiber slow down the digestion process, keep your body feeling satisfied for longer, and hold off that next wave of hunger for a while.

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