Sugary Drinks: Understanding Their Real Impact on Your Liver and Metabolism

# SUGARY DRINKS: WHAT SUGAR TRULY TRIGGERS IN YOUR LIVER, BLOOD, AND METABOLISM!

**Sodas, energy drinks, iced teas, sweetened coffees, juices, and sports beverages: research by Kimber Stanhope and Barry Popkin reveals why the problem goes far beyond calories and simple blood sugar levels.**

*By Laurent Glatz – for Athletic Carnivore*

You can consume sugar daily, maintain perfectly normal fasting blood glucose, yet still begin accumulating fat in your liver, alter your triglycerides, and gradually disrupt your insulin sensitivity.

This is precisely what makes sugary drinks so biologically intriguing.

Their impact isn’t limited to a temporary spike in blood sugar. Behind a simple can, multiple metabolic reactions can occur: intestinal absorption, fructose phosphorylation, changes in hepatic energy metabolism, lipid synthesis, and stimulation of uric acid production.

These phenomena don’t mean a drink automatically causes disease. But they explain why frequent and high consumption deserves close attention.

Two scientists help us understand this topic from complementary perspectives: Kimber L. Stanhope, who studies metabolic mechanisms in humans, and Barry M. Popkin, an expert on global shifts in dietary habits.

Their research leads to a fundamental question.

**What if you monitored your calorie intake without truly understanding what your drinks are doing to your metabolism?**

Kimber L. Stanhope: The Scientist Measuring Sugar’s Effects in the Body

**Kimber L. Stanhope, PhD**, is a researcher at the University of California, Davis (UC Davis), Department of Molecular Biosciences.

She earned a Bachelor of Science in 1978, a Master of Science in 1982, and a PhD in 2008—all from UC Davis—and is a registered dietitian in the United States.

Her research focuses on sugar metabolism, blood lipids, liver fat, insulin sensitivity, and cardiometabolic risk factors.

She participates in several National Institutes of Health (NIH)-funded research programs.

Her scientific specialty is directly studying physiological responses in participants given beverages of varying compositions, with biological measurements before and after intervention.

Her publications from 2009, 2015, and 2021 notably document the effects of drinks containing fructose, sucrose, or high-fructose corn syrup.

Barry M. Popkin: The Researcher Who Analyzed the Global Expansion of Sugary Drinks

**Barry M. Popkin, PhD**, is a distinguished professor of nutrition at the University of North Carolina at Chapel Hill, within the Gillings School of Global Public Health.

He holds a master’s degree in economics from the University of Wisconsin (1969) and a PhD in agricultural economics from Cornell University (1974). He has devoted decades to studying global dietary transformations.

Founder of his university’s epidemiological nutrition division, he also led an interdisciplinary obesity center funded by the NIH.

Author of over 600 scientific publications, he is known for the concept of *nutrition transition*, analyzing dietary changes accompanying economic and social shifts.

With Corinna Hawkes, he published a major 2016 study in *The Lancet Diabetes & Endocrinology* on the worldwide rise of sugary drinks.

**Stanhope analyzes biological reactions. Popkin studies how the food environment multiplies exposure to these drinks.**

This complementarity makes their work especially relevant.

The First Problem: Sugar Isn’t Just in Sodas

When sugary drinks are mentioned, many immediately think of Coca-Cola or other sodas.

But the dietary reality is much broader.

Classic energy drinks, carbohydrate-containing sports drinks, sweetened iced teas, flavored coffees with syrups, industrial milk chocolates, lemonades, fruit drinks, some flavored waters, and sweetened dairy preparations can all deliver significant sugar amounts.

Fruit juices are also implicated in the issue of free sugars, even when no sugar is added.

And the problem doesn’t vanish simply because a drink is labeled “natural,” “organic,” or “no added sugar.”

However, it’s important to distinguish product composition. A fruit juice, a sweetened dairy drink, and a soda don’t share exactly the same nutritional matrix nor necessarily the same metabolic effects.

The common mechanism we focus on here mainly concerns drinks delivering a rapid and significant amount of **glucose, fructose, or sucrose**.

Sucrose, or table sugar, consists of one glucose molecule linked to one fructose molecule.

Once digested, it provides roughly 50% glucose and 50% fructose.

High-fructose corn syrup (HFCS-55), used notably in many American sodas, contains about 55% fructose and 45% glucose.

The two formulations are metabolically similar despite industrial differences.

Comparative studies do not show HFCS to be systematically more harmful than sucrose at equivalent intake.

The real question isn’t just the sugar’s name.

**It’s the amount, the food form, consumption frequency, and the body’s capacity to handle it.**

First Biological Step: What Happens in Your Intestine When You Drink Sugar

A beverage containing sucrose enters the stomach, then the small intestine.

At the surface of enterocytes—the intestinal absorptive cells—an enzyme called sucrase hydrolyzes sucrose.

It releases glucose and fructose.

Glucose mainly crosses the intestinal apical membrane via the SGLT1 cotransporter, which uses the sodium gradient.

Fructose primarily uses a different transporter: **GLUT5**, encoded by the SLC2A5 gene.

Monosaccharides then enter the portal circulation, notably via GLUT2 on the basolateral side of enterocytes.

But an important discovery has changed our understanding of fructose.

The intestine is not just a passage organ; it metabolizes part of the absorbed fructose itself.

Enterocytes have enzymes to convert fructose into various metabolites, including glucose and lactate.

When intake exceeds intestinal processing capacity, a larger proportion of fructose reaches the liver via the portal vein.

The amount consumed and the rate of arrival influence how metabolism is divided between intestine and liver.

A liquid drink can be absorbed relatively quickly, especially when consumed alone. Actual speed depends on composition, concentration, gastric emptying, and meal context.

This first step already explains why rapidly drinking a large sugary beverage isn’t metabolically equivalent to consuming a similar sugar amount in a fiber-rich solid food.

Second Step: Glucose and Fructose Follow Different Metabolic Paths

Once absorbed, glucose raises blood sugar.

This elevation normally stimulates insulin secretion by pancreatic beta cells.

Insulin promotes glucose uptake by muscles and adipose tissue, supports glycogen synthesis, and regulates hepatic glucose production.

Fructose takes a different route.

In the liver, it is primarily processed by an enzyme called **ketohexokinase**, or fructokinase, especially its KHK-C isoform.

This enzyme rapidly phosphorylates fructose to fructose-1-phosphate.

The reaction consumes ATP (adenosine triphosphate), essential for cellular energy.

Fructose-1-phosphate is then broken down by aldolase B into two three-carbon molecules: dihydroxyacetone phosphate (DHAP) and glyceraldehyde.

Glyceraldehyde can be converted to glyceraldehyde-3-phosphate.

These compounds enter various energy metabolism pathways.

The key point is this.

In classic glycolysis, glucose passes through a regulatory step controlled by phosphofructokinase-1 (PFK-1).

**Fructose metabolized via the KHK–aldolase B pathway bypasses this regulatory step downstream.**

This bypass can, under high intake conditions, promote a large flux of three-carbon metabolites.

This doesn’t mean the liver can’t regulate fructose or that all ingested fructose immediately turns to fat.

Much can be converted to glucose, lactate, or stored as glycogen.

But this metabolic setup explains why high fructose intake can stimulate certain lipid synthesis pathways.

Third Step: How the Liver Can Produce Fat from Sugar

Here enters a fundamental mechanism: **de novo lipogenesis (DNL)**.

This is the production of new fatty acids from non-lipid substrates, notably carbohydrates.

When sugar metabolism intermediates sufficiently fuel energy pathways, they contribute to pyruvate formation, then acetyl-CoA.

Acetyl-CoA can then serve as a precursor for fatty acid synthesis.

In the cytosol, ATP-citrate lyase helps form acetyl-CoA from citrate.

Acetyl-CoA carboxylase (ACC) produces malonyl-CoA.

Fatty acid synthase (FASN) uses these substrates to synthesize new fatty acids, especially palmitate.

Simultaneously, triose metabolism provides glycerol-3-phosphate, necessary for assembling triglycerides.

Fructose can also stimulate transcription programs involved in lipogenesis, particularly via **ChREBP** (carbohydrate-responsive element-binding protein). Regulation of SREBP-1c may also play a role depending on metabolic context.

These factors alter expression of enzymes involved in lipid synthesis.

The result is significant.

The liver can increase triglyceride production without those triglycerides coming directly from dietary fat.

These triglycerides may be stored in hepatocytes or incorporated into very low-density lipoproteins (**VLDL**) destined to circulate in the blood.

High consumption of sugary drinks can thus contribute to two distinct phenomena: hepatic fat accumulation and increased circulating lipids.

Malonyl-CoA also regulates carnitine palmitoyltransferase 1 (CPT1), involved in transporting long-chain fatty acids into mitochondria.

When this pathway is inhibited, mitochondrial oxidation of some fatty acids may decrease.

The balance between lipid synthesis, oxidation, and export becomes critical.

**The biological problem isn’t just that sugar provides calories. It’s that it can alter how the liver produces, stores, and distributes fat.**

Fourth Step: Why Blood Triglycerides Can Increase

VLDL particles produced by the liver transport triglycerides to peripheral tissues.

These particles contain apolipoprotein B100, essential for their structure.

Increased hepatic triglyceride production can promote their export as VLDL.

At the same time, changes in apolipoprotein metabolism can affect their clearance.

Apolipoprotein C-III (apoC-III) is particularly notable: it slows degradation and clearance of triglyceride-rich lipoproteins.

Increased apoC-III activity can thus help maintain higher triglyceride levels in circulation.

This is one parameter studied by Kimber Stanhope’s team.

In their 2015 study, researchers observed a dose-dependent increase in several lipid factors after two weeks of consuming HFCS-containing drinks.

The average postprandial triglyceride increase reached about **37 mg/dL in the group receiving 25% of energy needs from HFCS**, versus near-zero change in the control group.

This variation was observed in a specific experimental protocol, not a prediction for every consumer.

But it shows biological changes can become measurable very quickly.

Fifth Step: Hepatic Fat Accumulation Can Disrupt Insulin Signaling

Triglyceride presence in the liver doesn’t automatically mean insulin resistance.

We must distinguish lipid storage from cellular mechanisms that truly impair insulin signaling.

When hepatic lipid metabolism becomes unbalanced, certain lipid intermediates—especially diacylglycerols (DAG)—can accumulate in specific cellular compartments.

These molecules can activate protein kinases like **PKCε**.

PKCε activation is implicated in models of hepatic insulin resistance, notably by affecting insulin receptor signaling.

Normally, insulin suppresses hepatic glucose production.

When this response weakens, the liver may continue producing excess glucose despite insulin presence.

The pancreas may then increase insulin secretion to maintain acceptable blood sugar.

This explains how someone can have normal fasting glucose yet develop insulin sensitivity abnormalities.

This doesn’t mean all fructose intake directly activates PKCε or inevitably leads to diabetes.

Insulin resistance has multiple causes, and the exact role of hepatic lipids depends on individual context.

But this mechanism clarifies why relying solely on blood glucose can miss part of the problem.

**Normal blood sugar alone doesn’t prove perfectly healthy hepatic metabolism.**

Sixth Step: How Fructose-Rich Drinks Can Raise Uric Acid

Here’s another fascinating mechanism, directly linked to our previous article on Dr. Richard J. Johnson’s work on fructose and gout.

Fructokinase phosphorylation of fructose consumes ATP.

When fructose flux is high, rapid ATP consumption can transiently lower intracellular energy reserves.

ATP breakdown increases ADP and AMP availability.

Some AMP is directed toward purine nucleotide degradation.

AMP deaminase converts AMP to inosine monophosphate (IMP).

Subsequent reactions produce hypoxanthine, then xanthine, before uric acid is formed by xanthine oxidoreductase.

In other words, **fructose can increase uric acid production without providing dietary purines itself.**

Xanthine oxidoreductase can also generate reactive oxygen species involved in oxidative stress mechanisms.

Experimental research suggests these phenomena may contribute to various metabolic disturbances, though their exact role in human disease remains context-dependent and not fully established.

In 2015, Kimber Stanhope’s team also observed a dose-dependent increase in average 24-hour uric acid levels.

In the highest HFCS dose group, the increase reached about **0.59 mg/dL** compared to baseline.

This doesn’t mean sugary drinks inevitably cause gout attacks.

But it demonstrates that the uric acid production pathway linked to sugar metabolism has measurable effects in humans.

Seventh Step: Why Drinking Calories Differs from Eating Them

The challenge with sugary drinks isn’t limited to the liver.

It also involves appetite regulation.

Satiety results from multiple signals: gastric distension, digestive nerve activity, intestinal hormones, energy availability, and integration by the central nervous system.

Chewing, texture, and ingestion speed also influence the eating experience.

A drink can deliver tens of grams of sugar in minutes without the fibrous structure or chewing associated with many solid foods.

Energy compensation is often incomplete: the body doesn’t always reduce subsequent meal intake proportionally to calories consumed in drinks.

This can promote caloric surplus.

Pure fructose causes a weaker acute blood sugar and insulin response than glucose, but this initial response shouldn’t be confused with its full metabolic effects.

Common drinks containing sucrose or HFCS generally provide both sugars.

Effects on ghrelin, leptin, GLP-1, and satiety vary by drink composition and experimental conditions.

It would be excessive to claim all sugary drinks systematically disrupt hunger hormones or cause addiction.

The best-established problem is more concrete: **it’s relatively easy to consume extra liquid energy without proportionally reducing other food intake.**

What Kimber Stanhope Has Truly Demonstrated

Three publications highlight the importance of her work.

In **2009**, a study with 32 overweight or obese adults compared 10 weeks of glucose-rich versus fructose-rich drinks, providing 25% of energy needs.

Both groups gained weight.

But only the fructose group showed significant visceral fat increase, unfavorable lipid changes, and reduced insulin sensitivity.

In **2015**, the team compared 85 young adults consuming HFCS drinks at 0%, 10%, 17.5%, or 25% of energy needs.

Within two weeks, several lipid markers and uric acid changed dose-dependently. The study had limitations, including short duration and lack of randomization between some groups.

In **2021**, a publication led by Desiree Sigala, with Kimber Stanhope as coauthor, provided new data on increased liver lipids and decreased insulin sensitivity after sucrose or HFCS drink consumption.

These studies don’t prove occasional consumption automatically causes disease.

But they show that high, repeated sugary drink intake can alter multiple metabolic parameters beyond what sweet taste or a single blood sugar reading might suggest.

What Barry Popkin Adds to This Biological Demonstration

Stanhope’s described mechanisms become especially interesting when placed in the context of dietary evolution.

Barry Popkin has precisely studied this transformation.

In his 2016 publication with Corinna Hawkes, he describes the growing importance of sugary drinks in many populations’ diets.

He analyzes differences between countries, product availability trends, and policy strategies aimed at modifying consumption.

His work shows that dietary habits aren’t just personal choices.

Availability, price, packaging formats, social habits, and marketing all influence consumption frequency.

A product once consumed occasionally can become a daily drink, sometimes multiple times a day.

And it’s this repetition that changes the scale of metabolic exposure.

**Stanhope shows what can happen inside the body. Popkin explains how part of our food environment encourages repeated exposure.**

Are All Sugary Drinks Biologically Equivalent?

No. And this distinction is essential.

A sucrose soda, an HFCS soda, pure fruit juice, chocolate milk, and a glucose sports drink don’t have identical compositions.

A drink mainly sweetened with glucose doesn’t stimulate fructolysis the same way as a fructose-rich drink.

A dairy drink also contains proteins, lactose, and sometimes fats that can alter digestion and metabolic response.

A fruit juice may provide vitamins, potassium, and plant compounds not found in soda.

Controlled research shows fructose-containing sugars’ effects depend heavily on their food source and energy context.

Some meta-analyses find particularly clear adverse effects for sugary drinks when they add energy to the diet, but not always when an equivalent intake replaces another nutrient.

A whole fruit is therefore not metabolically interchangeable with an industrial sugary drink.

Similarly, a “zero sugar” drink doesn’t trigger the fructose–fructokinase–uric acid cascade if it contains no fructose. Its other ingredients and potential effects are a separate question.

Scientific precision requires distinguishing products rather than condemning all by commercial name alone.

The Real Danger: Long-Lasting Invisible Biological Changes

This is probably the most important point.

You can regularly consume sugary drinks without noticeable symptoms.

Yet several phenomena may progress before obvious clinical abnormalities appear.

The liver can increase lipid synthesis.

Postprandial triglycerides can rise.

Insulin sensitivity can change.

Uric acid levels can increase.

These changes don’t necessarily occur together, nor are they exclusive to fructose.

But they explain why absence of symptoms alone doesn’t characterize metabolic health.

A single blood glucose test doesn’t directly reveal liver fat content, VLDL production, or post-meal insulin response.

Conversely, a disturbed biological marker alone can’t attribute cause solely to sugary drinks.

That’s why serious interpretation must relate multiple data: usual diet, body composition, metabolic history, physical activity, and relevant biological parameters.

What If You Changed Your Diet Without Identifying What Really Disrupts Your Metabolism?

Maybe you reduced dietary fats because your triglycerides were high.

Perhaps you cut certain solid foods, started counting calories, or increased fasting periods.

But have you examined the real role of sugary drinks in your daily habits?

And above all, do you know which mechanisms operate in your own body?

A carnivore or low-carb diet can greatly reduce added sugar exposure and improve some metabolic parameters. But it’s no universal guarantee against fatty liver, insulin resistance, or hyperuricemia.

The answer depends on initial status and other health determinants.

The work of Kimber Stanhope and Barry Popkin reminds us of two complementary realities: what we drink influences our physiology, and our food environment can make this consumption almost automatic.

At Athletic Carnivore, understanding your metabolic terrain means going beyond dietary slogans to identify what’s relevant in a specific situation.

Because removing a random food, watching only calories, or interpreting a single blood test can lead to correcting the wrong parameter.

**Before changing your diet again, the question may no longer be which diet to follow, but understanding what your body truly does with the foods and drinks you provide it.**

**Understand My Metabolic Terrain — [Athletic Carnivore](https://athleticcarnivore.fr/en)**

**And you, do you only watch what you eat, or have you truly understood what your drinks do to your liver, triglycerides, and insulin sensitivity?**

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Scientific Studies and References

**1. Stanhope K. L. et al. (2009)**

*Consuming fructose-sweetened, not glucose-sweetened, beverages increases visceral adiposity and lipids and decreases insulin sensitivity in overweight/obese humans.*

Journal of Clinical Investigation, 119(5), 1322–1334.

Clinical study on fructose vs. glucose beverage consumption over ten weeks and effects on visceral fat, lipids, and insulin sensitivity.

DOI: [10.1172/JCI37385](https://doi.org/10.1172/JCI37385)

**2. Stanhope K. L. et al. (2015)**

*A dose-response study of consuming high-fructose corn syrup–sweetened beverages on lipid/lipoprotein risk factors for cardiovascular disease in young adults.*

American Journal of Clinical Nutrition, 101(6), 1144–1154.

Study of dose-dependent effects of HFCS drinks on triglycerides, LDL cholesterol, apolipoproteins, and uric acid.

DOI: [10.3945/ajcn.114.100461](https://doi.org/10.3945/ajcn.114.100461)

**3. Sigala D. M. et al., including Kimber Stanhope (2021)**

*Consuming Sucrose- or HFCS-sweetened Beverages Increases Hepatic Lipid and Decreases Insulin Sensitivity in Adults.*

Journal of Clinical Endocrinology & Metabolism, 106(11), 3248–3264.

Trial examining liver lipid accumulation and insulin sensitivity changes after sugary drink consumption.

DOI: [10.1210/clinem/dgab508](https://doi.org/10.1210/clinem/dgab508)

**4. Popkin B. M. and Hawkes C. (2016)**

*Sweetening of the global diet, particularly beverages: patterns, trends, and policy responses.*

The Lancet Diabetes & Endocrinology, 4(2), 174–186.

Analysis of international sugary drink growth and their role in dietary transitions.

DOI: [10.1016/S2213-8587(15)00419-2](https://doi.org/10.1016/S2213-8587(15)00419-2)

**5. Stanhope K. L. et al. (2008)**

*Twenty-four-hour endocrine and metabolic profiles following consumption of high-fructose corn syrup-, sucrose-, fructose-, and glucose-sweetened beverages with meals.*

American Journal of Clinical Nutrition, 87(5), 1194–1203.

Study comparing glucose, fructose, sucrose, and HFCS effects on 24-hour metabolic and hormonal responses.

DOI: [10.1093/ajcn/87.5.1194](https://doi.org/10.1093/ajcn/87.5.1194)

**6. Jung S. et al. (2022)**

*Dietary Fructose and Fructose-Induced Pathologies.*

Annual Review of Nutrition, 42, 45–66.

Scientific review on fructose metabolism, enzymatic pathways, and effects on intestine, liver, and metabolic diseases.

DOI: [10.1146/annurev-nutr-062220-025831](https://doi.org/10.1146/annurev-nutr-062220-025831)

**7. Sievenpiper et al. — Systematic Review (2018)**

*Food sources of fructose-containing sugars and glycaemic control: systematic review and meta-analysis of controlled intervention studies.*

British Medical Journal, 363, k4644.

Analysis of 155 controlled trials examining effects of fructose-containing sugar sources on glycemic control.

DOI: [10.1136/bmj.k4644](https://doi.org/10.1136/bmj.k4644)

**8. Systematic Review and Meta-Analysis (2021)**

*Different Food Sources of Fructose-Containing Sugars and Fasting Blood Uric Acid Levels: A Systematic Review and Meta-Analysis of Controlled Feeding Trials.*

The Journal of Nutrition.

Analysis of 47 controlled trials studying relationships between sugar sources, energy balance, and uric acid levels.

[Scientific Publication](https://www.sciencedirect.com/science/article/pii/S0022316622003030)

**9. Popkin B. M. — Academic Biography**

University of North Carolina, Gillings School of Global Public Health.

[Academic Profile and Research](https://sph.unc.edu/adv_profile/barry-m-popkin-phd/)

**10. Stanhope K. L. — Academic Biography**

University of California, Davis, School of Veterinary Medicine.

[Academic Profile and Research](https://www.vetmed.ucdavis.edu/node/31826)

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