Wellness Wednesday: Understanding Sugars
When we talk about “sugar,” the conversation often gets reduced to “good” vs. “bad.” But in reality, sugars are a chemically diverse family of compounds with different origins, metabolic pathways, and impacts on health. As a dietitian, I often see confusion not just about how much sugar is “too much,” but also about what sugar even is. Breaking it down to the molecular level, and then zooming out to clinical data and everyday choices, helps clarify how sugars interact with the body, why they affect health outcomes, and how to navigate them wisely.
What Are Sugars, Really?
Sugars are carbohydrates that range from single-molecule monosaccharides to more complex disaccharides and beyond.
Glucose – the body’s primary energy currency. Rapidly absorbed, it drives blood sugar spikes and stimulates insulin release.
Fructose – found in fruit and honey, but also in high-fructose corn syrup. It’s metabolized primarily in the liver, where excessive intake can promote fat buildup through de novo lipogenesis.
Galactose – usually paired with glucose in lactose (milk sugar). Metabolized differently and less likely to cause large blood sugar spikes.
Sucrose – table sugar, a combination of glucose and fructose.
Lactose – the sugar in milk, composed of glucose and galactose.
Maltose – formed when starch is broken down; common in malted foods.
Beyond these simple sugars, we also have:
Oligosaccharides like raffinose and inulin, found in beans and vegetables. These act as prebiotics, feeding gut bacteria.
Polysaccharides like starch, which break down into glucose over time.
Each sugar has a distinct absorption pattern, hormonal response, and metabolic consequence.
How Sugars Work in the Body
Glucose is the most direct fuel, taken up by cells under the guidance of insulin. But not all sugars behave equally:
Glucose spikes blood sugar quickly, engaging insulin to shuttle it into cells.
Fructose bypasses insulin regulation. It heads straight to the liver, where excess is converted to triglycerides and stored as fat. This pathway helps explain why high fructose intake is linked to fatty liver disease and insulin resistance.
Galactose and lactose are digested more gradually, especially in people with intact lactase enzymes.
The way sugars are consumed matters, too. Liquid sugars (soda, juice) enter circulation rapidly and overwhelm regulatory pathways, while sugars bound in whole fruit come with fiber, slowing absorption and promoting satiety.
The Rise of Non-Nutritive Sweeteners
In the push to reduce added sugar, non-nutritive sweeteners (NNS) and sugar alcohols (polyols) have surged in popularity.
Artificial NNS – such as aspartame, sucralose, and saccharin. These provide intense sweetness without calories. Most are considered safe in regulated doses, though questions remain about long-term impacts on gut microbiota and glucose tolerance.
Naturally derived NNS – stevia and monk fruit extracts are plant-based, though still heavily processed.
Sugar alcohols – sorbitol, xylitol, erythritol, and others. They provide partial calories and often cause bloating or diarrhea at high doses because they are poorly absorbed in the small intestine. Recent research has even linked erythritol to possible cardiovascular risk, though findings are preliminary.
These alternatives reduce calorie and sugar intake, but they aren’t a free pass. Some studies suggest NNS may alter gut bacteria or disrupt appetite regulation in certain individuals.
Sugar, Health, and Disease
Decades of research connect excess added sugar intake to a range of chronic diseases:
Obesity and insulin resistance – High sugar intake contributes to excess calorie consumption and metabolic dysregulation. Over time, repeated insulin spikes can blunt insulin sensitivity, setting the stage for type 2 diabetes.
Type 2 diabetes – Observational studies consistently show a strong correlation between sugar-sweetened beverage intake and diabetes risk. Fructose, in particular, worsens insulin sensitivity when consumed in large amounts.
Cardiovascular disease – High added sugar intake increases triglycerides, lowers HDL cholesterol, and promotes visceral fat storage, all key drivers of cardiovascular risk.
Non-alcoholic fatty liver disease (NAFLD) – Fructose metabolism in the liver contributes to fat accumulation, inflammation, and eventual fibrosis in susceptible individuals.
Emerging research also suggests sugar intake may impact cognitive function, mood regulation, and even cancer risk, though these relationships remain under investigation.
Population Specific Considerations
Not all groups respond to sugar in the same way.
Children – High sugar intake shapes taste preferences early in life, fueling preference for hyper-sweet foods. The American Academy of Pediatrics recommends minimizing added sugar in children under 2 and limiting intake in older kids.
People with diabetes or prediabetes – Careful management of sugar intake is crucial. While natural sugars from fruit can be part of a balanced diet, added sugars and refined carbohydrates accelerate glucose excursions and worsen insulin resistance.
Gut health and the microbiome – Excess simple sugars promote dysbiosis, favoring bacteria linked to inflammation. Conversely, prebiotic fibers (a form of oligosaccharides) nourish beneficial gut microbes, supporting overall health.
Sugar and Satiety
Sugars differ in how they influence hunger and fullness. Liquid sugars bypass normal satiety cues, making it easy to consume large amounts without feeling full. Fructose, in particular, does not strongly trigger leptin (the “fullness” hormone) or suppress ghrelin (the “hunger” hormone) the way glucose does. This helps explain why sugary drinks are strongly tied to weight gain.
By contrast, sugars in whole foods, like fruit, come packaged with fiber, water, and micronutrients, which slow digestion, increase satiety, and reduce the likelihood of overconsumption.
Practical Guidance: A Dietitian’s Lens
Understanding the science is only useful if it translates into daily choices. A few practical strategies include:
Read labels carefully – Added sugars hide under dozens of names (cane syrup, agave nectar, maltodextrin, brown rice syrup). The “added sugars” line on Nutrition Facts is your best guide.
Prioritize whole foods – Opt for fruit instead of juice, whole grains instead of refined starches, and yogurt with minimal added sugar.
Increase prebiotic fibers – Beans, onions, garlic, and whole grains not only balance blood sugar but also support a healthy microbiome.
Hydrate with water first – Replace sugar-sweetened beverages with water, sparkling water, or unsweetened tea.
Taper gradually – If you sweeten coffee or tea, reduce sugar by small amounts over time to retrain your palate.
The Healthiest Path Forward
Sugar isn’t inherently toxic, but dose, form, and context matter. Glucose, fructose, and galactose each play different roles in metabolism. Added sugars, particularly in liquid form, are consistently linked to poor health outcomes when consumed in excess, while sugars bound in whole foods can be part of a balanced diet. Non-nutritive sweeteners and sugar alcohols offer alternatives, but they bring their own complexities and should be approached with balance.
For most people, the healthiest path forward isn’t total elimination but strategic reduction, label awareness, and a shift toward whole-food sources of sweetness. Pairing this with adequate fiber and hydration supports both short-term well-being and long-term health.
