Myth vs. science: do carbs lead to weight gain?

“If I eat carbs, I’ll gain weight.”

“Carbs are bad for me.”

Sounds familiar? You’ve probably heard this more than you can count. But here’s the truth: carbs don’t magically cause weight gain the second they hit your digestive system. Let’s unpack the science behind this all-too-common myth.

What are carbs, really?

Carbohydrates are one of the three macronutrients (alongside protein and fat) that make up the food we eat. They’re also your body’s go-to fuel, keeping your brain switched on, your msucles moving and your cells running smoothly.

You’ll find them in everyday foods like fruit, veggies, grains, beans, potatoes, pulses, dairy, and even sweeteners. Once eaten, your body breaks them down into simple sugars (mostly glucose). Some get used immediately for energy and the rest are tucked away as glycogen in your muscles and liver for later use. And because life doesn’t come with an “eat every 20 minutes” rule, that stored glycogen is key: it’s what keeps your energy (and brainpower) steady between meals.

So… why do carbs get such a bad reputation?

The “anti-carb” story usually goes something like this: high-carb foods spike blood sugar, which spikes insulin, which leads to fat storage. Sounds scary, right? Here’s the reality check:

• Storing fat is a normal, necessary process. Your body is constantly storing and releasing energy. It’s not a one-way trap

• A large number of studies show that you don’t need carbs to store fat. Overeating any nutrient (carbs, protein, or fat) can result in weight gain

• Several studies over the years have shown no consistent difference in long-term weight loss between low-carb and balanced diets

In other words, it’s not carbs themselves that lead to weight gain but eating more calories than your body burns over time that drives weight gain.

The “quick weight loss” illusion

Ever notice that when people cut carbs, the scale drops fast? That’s not fat melting away, it’s water. Here’s why: glycogen (what your carbs are stored as) clings to water. For every gram of glycogen, your body stores about three grams of water. Cut carbs, glycogen stores empty, water leaves and the scale dips. Bring carbs back in, and so does water.

Not all carbs are equal

This is where the nuance lies. Carbs come in three main types:

1. Sugars: short-chain carbs like table sugar, honey, and fruit sugars. They provide quick energy and a sweet taste

2. Starches: long chains of sugar molecules found in bread, pasta, rice, potatoes, cereals

3. Dietary fibre: technically a carb, but indigestible. It supports gut health, promotes satiety, and helps maintain steady energy

For practical purposes, we often talk about simple vs. complex carbs. Simple carbs (e.g., sweets, soda, pastries, refined grains) are digested quickly and can lead to sharp spikes (and crashes) in blood sugar. On the other hand, complex carbs (e.g., whole grains, legumes, fruits, vegetables) come packaged with fibre, vitamins, minerals, and antioxidants. They digest slowly, keep you fuller longer, and support overall health. Carbs aren’t inherently “good” or “bad”. What matters is understanding how different types of foods affect your body and energy.

Why balance matters

Pairing carbs with protein, fibre, and healthy fats slows digestion, stabilises blood sugar, and helps you stay fuller for longer. A hearty bowl of lentil soup with whole-grain bread will carry you much further than a can of soda, even if the calories were the same.

And yes, high in fat, sugar and salt carb-food like chips, cookies, cakes are hyper-palatable and easy to overeat. But whole-food carb sources like fruit, veggies, beans, oats, quinoa, deliver steady energy and nutrients that support heart health, hormone balance, energy and help prevent the development of several chronic diseases.

The bottom line

Carbs aren’t the villain they’ve been made out to be. They’re actually your body’s main energy source, especially for your brain and muscles! They also provide important fibre, vitamins and minerals that keep you healthy.

Instead of cutting carbs, focus on choosing the right kinds in the right amounts. Whole, fibre-rich carbs should be a cornerstone of your plate. Can we finally break-up with the “carbs are bad” myth? Trust me: your brain (and the rest of you) will be much happier for it!