Should You Be Worried About Carbs? The Science Behind Carbs and Your Health

Erika Rawes
Jun 11
4 min read

Carbs Aren’t the Enemy—But Not All Carbs Are Created Equally

Carbs have been blamed for everything from weight gain to brain fog. That's part of the reason why you see low-carb diets everywhere--Keto, Atkins, Carnivore, and more. The idea that “bread is bad” has practically become gospel.

But let’s cut the noise and look at the facts: Your body needs carbs--carbs are energy--you just need to be smart about which ones.

This post breaks down the difference between refined and complex carbs, how they affect your energy, health, and blood sugar, and how to include the right ones without guilt.

What Are Carbohydrates, Exactly?

Carbohydrates are one of the three main macronutrients (alongside protein and fat).

They include:

• Sugars (glucose, fructose, sucrose)

• Starches (in bread, pasta, grains, potatoes)

• Fiber (non-digestible plant matter that supports digestion)

When you eat carbs, your body breaks them down into glucose (blood sugar), which fuels your cells.

Glucose is the brain’s preferred energy source—especially during mental activity. According to a Harvard Medical School publication, "because the brain is so rich in nerve cells, or neurons, it is the most energy-demanding organ, using one-half of all the sugar energy in the body."

Carbs Aren’t “Bad”—But Processed Ones Can Be

The issue isn’t carbs—it’s highly refined carbs that spike your blood sugar and leave you crashing soon after.

Examples of Refined Carbs:

• White bread

• Pastries

• Chips

• Soda

• Sweetened cereals

**These are stripped of fiber and nutrients. They hit your bloodstream fast, cause energy crashes, and contribute to weight gain. Why? Because of processing. Processing takes foods and removes some of the natural fiber, vitamins, and minerals to produce a tastier and more shelf-stable product. That tasty product is often not as healthy for you though.

Example of Complex Carbs:

• Whole grains (quinoa, brown rice, oats)

• Fruits and vegetables

• Legumes (beans, lentils)

• Sweet potatoes

These digest more slowly, stabilize blood sugar, and keep you full longer.

**Harvard research shows that higher fiber, whole-food carb intake is associated with a lower risk of chronic disease. Complex carbs are considered the "good" kind.

The Science Behind Carbs--What Happens to Them in Your Body?

Each time you eat carbs, here's the science behind what happens with those carbs inside your body:

You eat a carb-rich food.
Your body breaks it down into glucose.
Insulin (a hormone) helps move that glucose into your cells for energy.
If there’s too much glucose (or if insulin doesn’t work as well as it should), it gets stored as fat.

That’s why the quality and amount of carbs matter—not because carbs are evil, but because your blood sugar and insulin response are real biological processes.

The CDC notes that choosing high-fiber, low-added-sugar carbs is key to blood sugar balance and long-term health.

Low-Carb vs. Balanced Carb: What Works Better?

Low-carb diets can lead to short-term weight loss, mainly because they reduce:

• Processed food intake

• Overall calories

• Water weight (stored carbs = stored water)

But they’re not magic. And, they’re hard to sustain. The science behind carbs, and eating them properly, is more complex than just avoiding them altogether.

A better approach for most people? Eat balanced carbs from real food. Enough to fuel your brain, workouts, and recovery—without crashing or overdoing it.

A 2022 study in The Lancet found that moderate-carb diets rich in plant-based foods were associated with the longest lifespan and lowest disease risk.

How Much Carbohydrates Do You Actually Need?

There’s no one-size-fits-all, but most dietary guidelines suggest:

• 45–65% of total calories should come from carbohydrates

• That’s about 225–325g/day on a 2,000-calorie diet

• But your needs may be higher or lower depending on activity level, goals, and metabolism

If you’re aiming for fat loss, you can go lower—but don’t ever eliminate carbs completely unless you're medically advised to do so.

Real-Life Smart Carb Swaps

You don’t have to give up carbs. Just upgrade them. Here are a few swaps you can use:

White bread	100% whole wheat or sprouted grain bread
Instant oatmeal packet	Rolled oats + cinnamon + berries
Sugar-loaded granola bar	Nuts + fruit or plain protein bar
White rice	Brown rice, quinoa, or farro
Juice	Whole fruit + water or tea

What About Fruit?

Fruit contains natural sugar, yes—but it also comes with fiber, water, vitamins, and antioxidants.

Fruit:

• Does not cause blood sugar spikes like refined carbs

• Many fruits are linked to lower risk of diabetes, not higher

• Can be part of nearly every healthy eating plan

The USDA and Harvard both recommend eating fruit each day as part of a balanced diet. MyPlate says your daily fruit serving amount depends on age, sex, height, weight, and physical activity, but eating some fruit every day is ideal.

Carb Myths—Busted

Myth 1: “Carbs make you fat.”

Truth: Eating too many calories of any kind makes you gain fat. Carbs are just easier to overeat when they’re ultra-processed. Plus, eating too many refined carbs makes you more likely to gain fat around the midsection.

Myth 2: “You don’t need carbs.”

Truth: Your body can technically survive without carbs—but it won’t thrive. Especially for brain function, hormones, and performance.

Myth 3: “Fruit is bad because it has sugar.”

Truth: Natural sugar isn’t the same as added sugar. Fruit is packed with benefits, as it contains fiber, water, vitamins, and minerals.