Is Sugar Really 'Poison'?

During an April 22, 2025, press conference, U.S. Health and Human Services Secretary Robert F. Kennedy Jr. stated, “Sugar is poison, and Americans need to know that it is poisoning us.” Normally, when experts refer to “poison” dramatically, we mean drugs like fentanyl that kill you immediately. Or arsenic, which kills you slowly (as when a person unknowingly receives arsenic from a malevolent source). Kennedy was using dramatic license to make a major point.

RFK, Jr. was invoking the first thing you learn in medical toxicology, the Renaissance German scientist Paracelsus’ principle: “The dose makes the poison.” Acknowledging the challenges in eliminating sugar from the food supply, Kennedy advocated better labeling and public education. He also mentioned the upcoming Dietary Guidelines for Americans recommending zero added sugar consumption.

He also highlighted the alarming rise in diabetes, noting that a typical pediatrician might have encountered just one case decades ago, but now one in three children are affected. He cited a National Institutes of Health (NIH) study indicating that 38 percent of American teens are diabetic or pre-diabetic, as is half the adult population. Kennedy, Jr. warned that national spending on conditions like diabetes rivals our military budget, posing an existential threat to the country’s future.

The Sugar Industry’s Perspective: Sugar Is Not So Bad

Courtney Gaine, Ph.D., president and CEO of The Sugar Association, responded, “Secretary Kennedy has promised gold-standard scientific reviews to support healthy diets, which we are confident will again reaffirm that real sugar in moderation plays an important part in balanced diets and that demonizing added sugars alone is counterproductive.” Gaine emphasized that sugar has been consumed for millennia, and current U.S. consumption levels are at a 40-year low, even as obesity rates continue to rise.

Some clinical health professionals express concern that alarmist language could exacerbate conditions like orthorexia nervosa, an unhealthy obsession with food purity.

Looking Back

Kelly Brownell, Nora Volkow, and I started the conversation about sugar, food, and obesity at the Yale Historic Conference on Food in 2007. We stated that “Overeating and obesity are candidates for addictive disease, and such a hypothesis is both testable in humans and can produce novel approaches and treatments for a major public health problem.”

I talked about sugar compared with fermented sugar (alcohol), observing that highly palatable food can produce the same effects as drugs of abuse. “It is common for people to eat more than they intend despite dire consequences,” like diabetes and liver disease, I said then. And also, “Failed diets and attempts to control overeating, preoccupation with food and eating, shame, anger, and guilt look like traditional addictions.”

Habitual Sugar Overconsumption and Addiction

Here’s how sugar might be framed as “poison.” Habitual overconsumption (especially of added sugars and refined carbohydrates) is strongly linked to type-2 diabetes, non-alcoholic fatty liver disease, obesity, and cardiovascular conditions. These disorders lead to millions of premature deaths, slowly over time.

A high intake of fructose (high-fructose corn syrup, a common ingredient in ultraprocessed foods and sweetened beverages) bypasses insulin regulation, overloading the liver and leading to fat creation, insulin resistance, and liver inflammation. Ashley Gearhardt and I also compared consuming hyperpalatable foods with sugar’s rapid effects on dopamine and insulin systems, promoting loss of control and eating with addiction-like behaviors, especially in children.

Comparing the Toxic Effects of Excess Alcohol wth Sugar Overconsumption

Alcohol is more convincingly a true poison than sugar in acute and chronic settings. The key difference between sugar and alcohol is that alcohol is a fast-acting, visible toxin—its harms are immediate, and its dangers are widely recognized. In contrast, sugar's harms unfold over years and are embedded in the food supply, often without consumer awareness.

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A high enough dose of alcohol (e.g., blood alcohol concentration greater than 0.4 percent) can kill in a single sitting by suppressing respiration. Even in moderate doses, alcohol causes oxidative stress, fatty liver, gut permeability, and neurotoxicity. Alcohol has a well-established addiction profile, hijacking the brain’s reward circuitry.

Alcohol contributes to 140,000-plus deaths per year in the U.S., including accidents, liver failure, and cancer. Alcohol is also a cause of violence and economic loss. Unlike alcohol, which is highly labeled and regulated, sugar is often hidden in food products, making unintentional overconsumption more likely.

What Experts Say

Dr. Nicole Avena, author of Why Diets Fail, and known for proving sugar addiction in rodent models, has said, “Our studies show that sugar bingeing leads to changes in dopamine receptors, tolerance, and withdrawal—hallmarks of addiction.” She also says, “Sugar is as addictive as cocaine.”

Dr. Ashley Gearhardt, a psychologist at the University of Michigan and developer of the Yale Food Addiction Scale, reports, “When we scan the brains of people who compulsively overeat sugar-laden foods, we see the same reward circuitry activation patterns that we see in drug addiction.” Dr. Gearhardt argues that certain modern foods meet criteria for substance use disorders, particularly those high in sugar and low in fiber or protein.

Dr. Robert Lustig, author of Fat Chance and a central figure in the sugar-as-poison anti-sugar movement, has said, “Sugar is not just empty calories; it’s toxic calories... the definition of toxicity is: the degree to which a substance can damage an organism. Poisons can be low-dose or high-dose, and acute or chronic. So sugar is a high-dose chronic toxin. It’s still a toxin. "

Dr. Brownell (former dean of Duke Sanford School of Public Policy), one of the first scholars to link the food environment to obesity, has said, “Sugar-sweetened beverages are the single biggest contributor to the obesity epidemic.”

Most recently, Dr. Dana Small, currently the Canada Excellence Research Chair in Metabolism at McGill University, conducted pioneering research on how modern diets—particularly rich in sugar and fat—alter brain function and behavior. In a 2023 study published in Cell Metabolism, Dr. Small and colleagues demonstrated that habitual consumption of high-fat and high-sugar foods changes the brain’s pleasure processing. The brain rejects low-fat foods and desires highly palatable foods due to enhanced brain responses to fatty and sugary food cues, suggesting that Western diets may rewire neural circuits related to reward and motivation.

Summary

Are you endangering your life by eating a sugar-laden diet? Not immediately, but perhaps over time. Secretary Kennedy’s description of sugar as “poison” put the spotlight on sugar’s long-term effects, including loss of control and heavy overconsumption of sugary products by American children and adults.

It was about time for those of us who organized and spoke at the Yale Historic Conference on Food and Addiction in 2007! I think excessive consumption of sugar is a real problem that I hope Secretary Kennedy, healthcare professionals, and parents can resolve.