Lose weight. Think better. Boost productivity. Live well.

How a High-Sugar Diet Affects Your Memory

Let's talk about how sugar affects the brain. If you're becoming forgetful, the culprit may not be your busy life, or your age, it may be your sweet tooth.

With documentaries like That Sugar Film causing a raucous in the documentary space, the nutrition world is currently ablaze with debate regarding sugar’s role in neurocognitive function and disease pathologies. This isn’t a new argument.  In fact, it was an argument about sugar that gave birth to the low-fat food industry back in the 1950s.

Fast forward 60 years and it would seem the low-fat diet craze has become synonymous with high-carb diet. Why? Because no distinction was made between good fats and bad fats, and no distinction was made between good carbs and bad carbs.

So, we have a real epidemic on our hands. I’m going to skip sounding the alarm about the high instances of overweight and obesity, and skip talking about how Type 2 Diabetes is becoming the norm, even for school-aged kids.


In part 1 of this piece (which you can read here), I focused on clarifying the different types of sugars and how you get them. I will lead this section with a reminder: The impact different foods have on your body is also affected by the bacteria in your gut.

Vera Novak, MD, PhD, an HMS associate professor of medicine at Beth Israel Deaconess Medical Center says long-term diabetes—either type 1 or type 2—has many consequences for the brain and for neurons in the brain, due to their tendency to induce high levels of blood glucose over long periods of time.

Some findings in the International Review Journal of Advances in Nutrition seemed to give weight to the negative neurocognitive effects of consuming too much sugar.

Human studies using an fMRI machine examine human responses to different types of sugar, including aspartame and maltodextrin.  When calories and sweetness were present, reward pathways within the brain were stimulated. This “eat sweets, get a reward” biochemistry is the foundation of the pervasive belief by many in the medical community that sugar is addictive.


“It is of vital importance to understand how the foods which are making us fat also act to impair cognition.” – An excerpt from an abstract of the publication, Diet-Induced Cognitive Deficits: The Role of Fat and Sugar, Potential Mechanisms and Nutritional Interventions (Beilharz, Maniam, and Morris)


The Hippocampus is part of the limbic system, that part of your brain responsible for regulating emotions, reactions, memory, and the autonomic nervous system.  Impairments to this part of the brain have been linked to problems with long-term memory, episodic memory (like remembering that you had a cheeseburger 90 minutes ago), and spatial relation (remembering the route to work).

According to an article published to the NIH’s Library of Medicine, diet-induced inflammation  that is the result of chronic high-calorie diet (in the article, they lovingly refer to it as a “high-energy diet”) can cause long-term low-grade inflammation. But diets that are high in fat AND high in sugar can bring on inflammation quickly and trigger cognitive deficits rapidly, without warning and without obesity. A study using rodent models indicated that 1 to 3 days was all it took to trigger inflammation, and that inflammation two, on average, two weeks to subside.

Diets high in fat and sugar also reduce brain plasticity (your brain’s ability to change) by reducing brain-derived neurotrophic factors (BDNF). BDNF is a protein that keeps the brain healthy by improving the function of neurons and strengthening them to protect them from deterioration.

Other findings suggest an association between high consumption of refined carbohydrates, or simple sugars, and cognition issues.  The risk of mild cognitive impairment or dementia in older persons goes up when people get too much of their energy from carbs.  The flip side is these risks drop dramatically when you get a higher percentage of your energy from [good] fat and protein.

Fix Diet-Induced Memory Loss by Changing Your Diet?

If you’ve been following the ketogenic diet for any amount of time, you may know that the diet actually began as a treatment to reduce the number of epileptic seizures occurring in children. At the beginning of the 20th century, scientists (doctors) like Bernard McFadden, Hugh Conklin, and Russell Wilder (the doctor who coined the term “ketogenic diet”) discovered that by severely restricting the intake of carbohydrates and forcing the body to rely largely on ketone bodies for fuel instead of glucose, you could curb epileptic seizures, altogether.

One hundred years later, and you can search Twitter for loads of stories from parents who transitioned their kids to an ultra low-carb diet to help increase focus, improve study skills, boost memory, and decrease the number of seizures. In each instance, the only recorded change is changing what their kids eat.

It’s also worth noting that eliminating sugars and boosting the intake of healthy fats and protein is also one of the ways doctors treat neurodegenerative diseases like Alzheimer’s Disease, Parkinson’s Disease, as well as epilepsy.

Science supports the fact that increasing the amount of omega-3 fatty acids and decreasing the amount of omega-6 fatty acids helps boost brain health. You want to keep the ratio of omega 6 to Omega 3 of 4:1. Taking the supplement curcumin (probably in your spice rack under the name turmeric) also helps reduce inflammation and reverse the effects of what I can only refer to as sugar damage.

The bottom line: There is a strong link between increased inflammation (caused by a high-sugar diet) and your brain’s ability to generate new neurons. Fructose is in just about everything we eat these days, and it is a major accelerator of cognitive deficits and insulin resistance. You can offset some of the effects of added sugars by boosting your intake of omega-3 fatty acids.


Comments are closed.