What Sugar Does to Your Body

We have explored protein, low-carb vs. low-fat diets, and now it’s time to take a deep dive into carbohydrates - what they are, how they function, and their close relationship with sugar. Many people don’t realize that sugar is a type of carbohydrate. While some carbs are essential for energy, others, particularly refined sugars, can lead to serious health issues.

In this blog, we will focus specifically on sugar, how the body processes it, and why its overconsumption is a growing problem. By understanding how glucose and fructose work in the body, you can make informed choices about your diet.

Glucose vs. Fructose: Which is Worse?

Sugar, also known as sucrose, is made up of two smaller sugar molecules: glucose and fructose. These two components are handled very differently by the body.

What happens when you eat sugar?

• Glucose is the body’s main energy source. When consumed, it enters the bloodstream and triggers the pancreas to release insulin, which helps shuttle glucose into cells for energy.
• Fructose bypasses insulin regulation and goes directly to the liver. If the liver is already full of stored energy, it converts fructose into fat.

Does fructose cause fatty liver? Yes. Over time, excess fructose leads to fatty liver disease, contributing to insulin resistance and making it harder for the body to regulate blood sugar.

When we eat sugar-filled snacks, only half of the energy enters the body as glucose, while the other half-fructose-gets processed in the liver and often turns into fat. This is why excessive fructose consumption is linked to obesity and metabolic disorders.

How Our Diets Have Changed Over Time

Hundreds of years ago, humans consumed very little sugar. Natural sources, like honey and seasonal fruits, were rare and eaten in moderation. Today, sugar is everywhere. Processed foods, fast food, and sugary drinks have drastically increased our sugar consumption beyond what the body was designed to handle.

Animals in the wild consume sugar in ways that benefit survival. Bears gorge on berries before hibernation, storing fat for winter. Humans evolved in a way where sugar was a rare find, meaning our bodies store excess sugar as fat because they assume famine is coming - but in modern times, that famine never comes.

Lewis Cantley, an American cancer researcher, has highlighted how our modern sugar overload fuels disease. He warns that fructose is particularly harmful because it forces the liver into overdrive, creating long-term metabolic damage.

Is Fruit Juice as Bad as Soda?

A half-liter of cola contains the equivalent of 14 teaspoons of sugar. Unlike sugar in solid food, liquid sugar enters the bloodstream almost instantly, overwhelming the liver and forcing it to store fat. Studies show that drinking just one can of soda per day can significantly increase the risk of fatty liver disease.

Is fruit juice healthier than soda? No.

• The fiber in whole fruit slows sugar absorption, preventing blood sugar spikes.
• Juice removes this fiber, making it behave exactly like soda in the body.

Artificial Sweeteners: Are They Worse Than Sugar?

Many people turn to artificial sweeteners like aspartame, saccharin, and sucralose as an alternative to sugar. While they contain zero calories, they may be even more harmful than sugar itself.

A study from an Israeli research team, published in Nature, found that artificial sweeteners disrupt gut bacteria, altering metabolism and reducing the body’s ability to process glucose properly. Over time, this can lead to insulin resistance and diabetes.

What happens when you consume artificial sweeteners?

• They change the balance of gut bacteria, making it harder for the body to handle glucose, which disrupts insulin signaling and affects blood sugar regulation.
• They increase cravings for sweet foods, leading to overeating and potential insulin spikes.
• Some studies suggest they contribute to chronic inflammation, which worsens insulin resistance and increases the risk of metabolic disorders like diabetes.

Why Does Fructose Make the Liver Fat?

One of the most damaging effects of excessive sugar consumption is fatty liver disease. The liver is not designed to store fat, but when overwhelmed with high amounts of fructose, it has no choice but to convert it into fat deposits.

This fat buildup blocks insulin function, forcing the body to produce more insulin, creating a cycle of insulin resistance and higher blood sugar levels. Fatty liver disease was rare decades ago but has become a major health issue due to modern diets filled with added sugars.

How Sugar Accelerates Aging

Beyond metabolic damage, excess sugar accelerates aging. A Harvard University study found that sugar shortens telomeres, the protective caps on our DNA, which speeds up cell aging.

How much does sugar age you?

• Drinking just one sugary drink per day can age cells by nearly five years - similar to the effects of smoking.
• High sugar intake doesn’t just affect weight - it affects longevity.

How to Reduce Sugar’s Harmful Effects

Cutting sugar completely is unrealistic, but reducing added sugar and prioritizing natural sugars in whole foods is key to improving health. The best approach is to:

• Avoid sugary drinks - they are the fastest way to overload the liver with sugar.
• Choose whole fruit over fruit juice - fiber slows sugar absorption and prevents metabolic damage.
• Limit processed foods - many grocery store staples, like yogurt, granola, and fast food, contain hidden sugars.

Simply eliminating sugar-sweetened beverages is already half the battle. Since liquid sugar doesn’t need to be broken down, it enters the bloodstream rapidly, making it more harmful than sugar from solid food.

Source: The Diet Compass - Bas Kast

Next Blog: Smarter Carb Choices

Next, we will explore other carbohydrates, their effects on metabolism, and how to make smarter carb choices for better health. Understanding the balance between complex and refined carbs can help you create a sustainable, healthy diet.