BiotiQuest® Gut Health & Probiotics Blog with Martha Carlin

Lose Weight for a Better Brain

Martha Carlin | Jul 19, 2021 | 4 minutes read

This article was written by Ken Kubota and was originally posted on Medium.

You’re trying to lose weight because you want to be slimmer, more attractive, active, and healthy. But there is one more powerful motivation when thinking about reducing your waistline….. a better brain!

Research has revealed that significant brain atrophy and cognitive impairment is attributed to obesity and insulin resistance (source1, source 2).

Age adjusted values of normalized brain volume (NBV) plotted versus BMI scores. NBV is shown to decrease proportionally with increasing BMI (r = -0.232, p < 0.03). Source- Ward MA, Carlsson CM, Trivedi MA, Sager MA, Johnson SC. The effect of body mass index on global brain volume in middle-aged adults: a cross sectional study. BMC Neurol. 2005;5:23. Published 2005 Dec 2. doi:10.1186/1471–2377–5–23

Above are the results from The effect of body mass index on global brain volume in middle-aged adults: a cross sectional study (, where brain volumes were measured from MRI scans of 114 adults. BMI is a measurement of obesity called the body mass index — body weight divided by height. A BMI of 31 and greater is considered obese. (See here if you are not familiar with the body mass index (BMI).)

A study that compared 41 Type 2 diabetic patients with 47 normal healthy people, controls, of the same age and sex found differences in memory, cognition, and hippocampus, area of the brain responsible for memory etc. In comparison to controls, the Type 2 Diabetics did not perform as well on memory and cognition tests. Furthermore, Type 2 diabetics had smaller hippocampal volumes than controls. Modifiers of cognitive function and brain structure in middle-aged and elderly individuals with type 2 diabetes mellitus — PubMed (

Hippocampal volume (cc) decreases with increasing BMI (kg/m2). Source — Bruehl H, Wolf OT, Sweat V, Tirsi A, Richardson S, Convit A. Modifiers of cognitive function and brain structure in middle-aged and elderly individuals with type 2 diabetes mellitus. Brain Res. 2009 Jul 14;1280:186–94. doi: 10.1016/j.brainres.2009.05.032. Epub 2009 May 20. PMID: 19463794; PMCID: PMC2749480.

The graph above from the study plots the volume of the hippocampus versus BMI. The hippocampus is a part of the brain that plays a major role in learning and memory. Depression, stress, and even Alzheimer’s disease appear to be linked to a smaller-sized hippocampus. The size of the hippocampus can be used to diagnose the progress of Alzheimer’s disease.

What is interesting to note in the graph is that it seems that even the healthy cohort, the ones without Type 2 Diabetes, are not immune from structural changes in the brain with increasing BMI. The trend begins even at the healthy levels of BMI, 25 and under.

Speaking of the waistline, people with excess accumulation of fat in the abdominal area have nearly a 3-fold risk for dementia (source) with a 27% increase in the number of lesions, injuries, in the brain detected by MRI, called white matter hyperintensities (WMH) — associated with low blood flow.


Is there anything you can do aside from the obvious, reducing your weight?

The good news is that aerobic fitness can reduce brain tissue loss (source). Picking up an aerobic fitness regimen, such as walking, swimming, cycling, etc., can increase your brain function (source). Aerobic exercise can make a meaningful difference to brain structures and their function — it enhances learning and causes the neurons in the brain to grow! (source). What is also interesting is the fact that scientists have found that exercise can also change your gut microbiota for the better. (source) Which brings us to the benefits of taking probiotics.

There is trending evidence that taking probiotics can both enhance cognition, improve your mood, and help you shed those excess pounds! Stress increases your craving for carbohydrates (source) and slows your metabolism. (source) A recent study showed probiotics can reduce stress under challenging situations. (source) A 30 day clinical study with participants taking a probiotic formulation of Lactobacillus and Bifidobacterium longum decreased the incidences of depression and anxiety. (source) Another study with 41 students under examination stress revealed that the ones who were administered Lactobacillus plantarum had lower cortisol levels, a stress hormone, than controls. Finally, a systematic review of 15 randomized controlled studies on the effect of probiotic supplementation on body weight, BMI, fat mass, and body composition by H. Borgerass et al (source), concludes that probiotic supplementation resulted in reduced body weight, BMI, and fat percentage. Many of the studies included the strains Bifidobacterium longum, Bifidobacterium bifidum, and Lactobacillus plantarum, species that can be found in Sugar Shift.

You can check out my own experience with probiotics here.

The greater implications of all of these findings point to what is known as the gut-brain axis, the communication between the central and the enteric nervous system. (By the way, a really good book by Scott C. Anderson on the gut-brain connection can be found here.) However, more recently, a greater understanding of how microbes regulate the gut-brain axis, AKA microbiota-gut-brain axis, is gaining traction– a topic for another discussion.

Yet another reason to keep you motivated on your weight loss journey, a better brain!

With gratitude,

Martha Carlin photo Martha Carlin, is a “Citizen Scientist”, systems thinker, wife of Parkinson’s warrior, John Carlin, and founder of The BioCollective , a microbiome company expanding the reach of science and BiotiQuest, the first of it’s kind probiotic line. Since John’s diagnosis in 2002, Martha began learning the science of agriculture, nutrition, environment, infectious disease, Parkinson’s pathology and much more. In 2014, when the first research was published showing a connection between the gut bacteria and the two phenotypes of Parkinson’s, Martha quit her former career as a business turnaround expert and founded The BioCollective to accelerate the discovery of the impact of gut health on all human disease. Martha was a speaker at the White House 2016 Microbiome Initiative launch, challenging the scientific community to “think in a broader context”. Her systems thinking background and experience has led to collaborations across the scientific spectrum from neuroscience to engineering to infectious disease. She is a respected out of the box problem solver in the microbiome field and brings a unique perspective to helping others understand the connections from the soil to the food to our guts and our brains.

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