Aspartame: Could it be increasing your anxiety and waistline? 


Today’s “Ask the Nutrition Consultant” post addresses some concerns that clients, friends and family have asked me regarding aspartame (Nutrasweet™ or Equal™) – an artificial or zero-calorie sweetener. I touched on some safety concerns in relationship to metabolism and cancers with aspartame in my “Are Artificial Sweeteners and Sugar Substitutes Safe?” post from 11/30/2022. Today I’ll be focusing on the metabolic and neurological concerns of aspartame usage.

Many of the women who seek my help have two major concerns they want to uncover the root cause of:
1. Unwanted weight gain and/or an inability to lose excess body fat.
2. Anxiety, depression and other neurological and mood concerns that zap them of joy and energy.

There are multiple nutritional and lifestyle factors that can impact our weight and moods. What I have noticed with some of my clients who are hit particularly hard by anxiety and a struggle to lose weight is that they regularly consume diet soft drinks sweetened with aspartame. While I am not saying that the aspartame sweetened soft drinks are THE cause of these issues, studies do show us that aspartame (and other sugar substitutes) do affect our metabolism and neurotransmitters. They can be part of the problem and it’s an area to look at and address if someone is dealing with these concerns.

First let’s look at metabolism and weight gain. Even though aspartame does not raise insulin levels, it does affect our metabolism and can cause the same metabolic disorders as real sugar. Aspartame (and other sugar substitutes) change the gut microbiome in ways that favor dysbiosis (an imbalance in gut microbes), blood sugar imbalances, and an overall unhealthy metabolism (Perlmutter & Loberg, 2015). Our gut microbiome is important because it contributes enzymes that are not encoded by the human genome. For example, gut bacteria produce enzymes that breakdown polysaccharides, polyphenols and help synthesize some vitamins (Rowland et. al., 2018). Our gut bacteria also produces neurotransmitters that affect our moods such as serotonin, dopamine, and noradrenaline. In fact approximately 95% of total body serotonin is made in the gut! Aspartame’s affects on our gut microbiome can affect not only our metabolism but our moods. 

Now let’s look at how aspartame is linked to behavioral and cognitive concerns such as learning problems, headache, seizure, migraines, irritable moods, anxiety, depression and insomnia. Aspartame (α-aspartyl-l-phenylalanine-o-methyl ester) can elevate levels of phenylalanine and aspartic acid in the brain. These compounds can inhibit the synthesis and release of the “happy” neurotransmitters dopamine, noradrenaline, and serotonin (Choudhary & Lee, 2018). Aspartame can also elevate cortisol levels and cause an increase in harmful free radicals which can increase the brain’s vulnerability to oxidative stress. Excessive oxidative stress can cause cell loss or even brain damage and can render the brain more prone to depression (Naidoo, 2020). Aspartame has also been implicated in triggering migraines in susceptible individuals (Newman & Lipton, 2001). 

We’re continually learning more and more about how the body works and how our diet and lifestyle choices affect our health and wellbeing. So far the research is showing us that aspartame is not health promoting and can even be harming us. It is our daily choices and habits that we repeat the most often that have the biggest impact on our health. Will the occasional diet soda (say 1 to 2 servings per month) disrupt our microbiome, brain, and metabolism that much? Likely not. But if beverages with aspartame (or other artificial sweeteners) are part of our daily or weekly intake then we will likely have issues. 

If you are dealing with stubborn body fat, anxiety or depression, or fatigue and feel like you are doing “all the things” and not seeing results I can help you. Together we will take a look at your diet, sleep, stress, environment and toxic load to uncover the root cause(s) and devise a plan to take you from surviving to thriving. Call or e-mail me to schedule a complimentary Nourish to Flourish Strategy Session with me to discuss your concerns and get started. 


Aoun, A., Darwish, F., & Hamod, N. (2020). The Influence of the Gut Microbiome on Obesity in Adults and the Role of Probiotics, Prebiotics, and Synbiotics for Weight Loss. Preventive nutrition and food science, 25(2), 113–123.

Choudhary, A. K., & Lee, Y. Y. (2018). Neurophysiological symptoms and aspartame: What is the connection?. Nutritional neuroscience, 21(5), 306–316.

Humphries, P., Pretorius, E., & Naudé, H. (2008). Direct and indirect cellular effects of aspartame on the brain. European journal of clinical nutrition, 62(4), 451–462.

Naidoo, U. (2020). This is your brain on food. New York, NY: Little, Brown Spark.

Newman, L. C., & Lipton, R. B. (2001). Migraine MLT-down: an unusual presentation of migraine in patients with aspartame-triggered headaches. Headache, 41(9), 899–901.

Perlmutter, D., & Loberg, K. (2015). Brain maker: the power of gut microbes to heal and protect your brain–for life. Large print edition, First edition. New York, NY, Little, Brown and Company.

Rowland, I., Gibson, G., Heinken, A., Scott, K., Swann, J., Thiele, I., & Tuohy, K. (2018). Gut microbiota functions: metabolism of nutrients and other food components. European journal of nutrition, 57(1), 1–24.

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