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6 Mental Health Effects of Eating Too Much Sugar

September 4, 2023

Although sugar makes everything taste sweeter, eating too much sugar can adversely affect our health. For starters, it’s linked to diabetes, obesity, unhealthy blood triglyceride levels, and even cardiovascular disease. And this is just the physical effects on the body — eating too much sugar can also negatively impact our mental health.

Before we get into it, Melanie Murphy Richter, MS, RDN, a registered dietitian nutritionist and instructor of Nutrition Physiology at the University of California Irvine, explains that it’s important to clarify that not all sugar is considered unhealthy for the body.

“For instance, natural sugars from whole fruits, complex carbohydrates, and starchy vegetables provide many important nutrients to the body,” she says. “Natural sugars are not typically a source of negative mental health effects.”

Murphy Richter points out that, typically, it’s the excessive consumption of added sugar that is the bigger issue. “Added sugar is one of the biggest and most problematic nutrition-related issues that we are faced with today,” she says. Murphy Richter explains that it’s one of the “main drivers and causes” of some of the top chronic illnesses the population faces, including diabetes, heart disease, cancer, and obesity. “It’s also associated with depressive symptoms, anxiety, and cognitive decline,” she adds.

Ahead, we take a closer look at the mental health effects of eating too much sugar.

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1. Mood swings

Eating too much sugar can cause fluctuations in blood sugar levels. “When your blood sugar spikes, you might experience a temporary boost in mood and energy,” says Dr. Benson Munyan, PhD, a board-certified psychologist, professor of psychology at the University of Central Florida, and the director of Neurocove Behavioral Health in Orlando, FL. “However, once your blood sugar crashes, you may feel irritable, fatigued, or even anxious.” Munyan points out that these frequent shifts in mood can hurt your overall mental well-being.

Murphy Richter echoes this sentiment. “People who eat too much sugar often experience extreme glucose spikes throughout the day that are accompanied by extreme glucose crashes,” she says. She explains that when our body goes through this “rollercoaster of glucose regulation,” mood swings, irritability, and anxiety are not uncommon.

“Over time, this can lead to the development of depression,” she continues. “High sugar diets have shown to decrease the production of necessary neurotransmitters like serotonin, which plays an important role in mood regulation and mental well-being.”

2. Impaired cognitive function

Munyan also shares that eating too much sugar can harm cognitive abilities, including memory and learning. “Studies have shown that excessive sugar consumption can impair synaptic activity,” Munyan explains. “This can lead to difficulties in concentration, focus, and overall cognitive performance.”

3. Increased anxiety

Munyan also points out that eating too much sugar can worsen feelings of stress and anxiety, as mentioned in a 2019 review in the Neuroscience & Biobehavioral Reviews. “When we consume sugary foods, our body releases a surge of insulin to help regulate blood sugar levels,” Munyan shares.

“This insulin release is often followed by a drop in blood sugar, triggering a stress response in the body.” Munyan goes on to explain that this physiological reaction can exacerbate feelings of anxiety.

4. Negatively affects the ability to sleep

You may not realize it, but eating too much sugar can also wreak havoc on your sleep. “Too much sugar, especially consumed later in the day, can interfere with proper circadian function and impair our ability to fall and stay asleep,” Murphy Richter mentions.

She also points out that when we don’t sleep properly, we risk additional internal inflammation, which can interfere with our body’s ability to heal itself. “This can worsen existing health conditions, too,” Murphy Richter adds.

5. Impairs memory and learning abilities

If you think eating too much sugar doesn’t affect memory or learning functioning, think again. “Too much sugar intake can affect our short-term memory and make it more difficult for us to learn and process information,” Murphy Richter says.

6. Reduces ability to manage stress 

Murphy Richter says that eating excess sugar can dampen our hypothalamic-pituitary-adrenal (HPA) axis, reducing the ability to manage stress. “Our HPA axis is an important component of the body’s stress response system,” Murphy Richter explains. “When our HPA axis is out of balance and dysregulated, it can lead to various stress-related disorders like anxiety and depression.” She says it can also result in mismanaged stress and may even make us perceive it as more threatening and harder to handle.

7. Higher risk of certain neurodegenerative diseases

Lastly, Murphy Richter shares that eating too much sugar can raise levels of internal inflammation, therefore upping the risk of developing certain neurodegenerative diseases.

“Excess sugar consumption can lead to chronic inflammation in the body, which is a direct contributing factor in the development of various neurodegenerative conditions, including Alzheimer’s disease and dementia,” she says.

Read next: I Reduced My Sugar Intake and Drastically Changed My Heart Health. Here’s How.

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