Hi! My name is Caley!
A bit about me: I am a PhD student studying Neurobiology at Duke. I am really excited to join Body Banter because I am incredibly passionate about the topics of body image, self-confidence, and mental/physical wellbeing. As a graduate student studying the brain, I am very interested in the biological bases of body image, eating disorders, and other mental health challenges. I’m also fascinated by how diet and exercise affect brain health. I can’t wait to share what I’ve learned and nerd out with you about all of these exciting neuro topics on my column!
Have questions or things you want to learn more about? Feel free to reach out- I’d love to hear from you!
When you think of someone getting stronger, what do you envision?
Bigger muscles (hypertrophy)? Being able to lift heavier weights? Better muscle endurance?
If you’re anything like me, you’re thinking almost exclusively about muscles themselves. But recently, I’ve begun to appreciate that that’s just one part of the story. Every muscle in your body is connected to nerves that control when and how much your muscle contracts or relaxes. When you do a tough workout, you are challenging not only your muscles, but also the nerves that wire to, or innervate, those muscles. It’s these nerves that are responsible for how many muscle fibers contract at the same time when you lift a weight, as well as how efficient those contractions are.
How do nerves change with strength training?
A recent study from researchers at the University of Nebraska-Lincoln began to address this question1. They recruited men in their mid-20s to complete a strength-training regimen. Throughout the study, the men would train their quads on a leg extension machine while the researchers measured lots of different variables. At the start of the study, they recorded each participant’s one-rep max (1RM, the absolute heaviest weight he could successfully lift on the leg extension machine).
The participants were then randomly assigned to complete one of two training programs 3 days a week for 6 weeks:
1. Complete as many leg extensions at 30% of their 1RM as possible, until failure.
2. Complete as many leg extensions at 80% of their 1RM as possible, until failure.
For instance, let’s pretend your 1RM was 100 pounds. If you were in the 30% group, you’d complete as many 30-pound leg extensions as possible, until you physically couldn’t complete any more repetitions. If you were in the 80% group, you’d do the same thing, except with 80 pounds. At the end of the 6-week programs, the researchers wanted to know which group had bigger quad muscles, which men’s legs had gotten stronger, and whether the neural activity in their legs had changed.
Personally, I love to lift heavy weights. As a woman, I’ve always found that feeling that comes from heavy lifting to be both emotionally empowering and physically rewarding (more on that in another post!). Needless to say, my bias while reading this study was that the “Heavy Lifters” were going to be way stronger and have bigger muscles than the “Light Lifters”. Not the case! At least, not the case if you only look at muscle hypertrophy. The quad muscles of both groups grew the same amount, regardless of whether the participant lifted heavy or light. As long as both groups were working until their muscles were fully fatigued at the end of each set, their muscles grew.
Both groups were also able to lift more total weight at the end of the 6 weeks than they could at baseline. However, the Heavy Lifters had bigger gains in their max strength (aka their new 1RM) than the Light Lifters.
If this couldn’t be explained by muscle size increase alone, what could cause this difference?
Intriguingly, the answer seems to lie in the adaptations made by the nervous system! At the end of the 6-week period, the Heavy Lifters’ leg nerves were more active during their maximum output, but less active during sub-maximal efforts. In other words, there was more potential for nerve activity when it was required (like during max-effort lifts), but the activity was also more efficient (during sub-maximal lifts).
This study blew my mind for several reasons. First, I think a lot about what happens to the brain when you exercise, but I’d honestly never thought much about what happens to your nerves themselves. It fascinates me that our nerves can adapt and improve their efficiency in just a few short weeks. I also think it’s super cool that particular types of training stimuli (light vs. heavy lifting) elicit difference changes to the nervous system. This study is just the tip of the iceberg for understanding how nerves change with exercise. For example, this type of study would need to be repeated with women, as well as older and younger individuals, to see whether these neural changes occur in the same way across different populations.
Regardless, it did make me appreciate just how hard our bodies work to adapt to the challenges we place on them. It’s also a great reminder of the importance of good rest and recovery after tough workouts- our bodies are doing A LOT on those rest days to adapt to the stimuli we’ve provided!
Learn more here:
1. Jenkins, N., Miramonit, A., Hill, E., Smith, C., Cochrane-Snyman, K., Housh, T., & Cramer, J. (2017). Greater neural adaptations following high vs. low-load resistance training. Frontiers in Physiology, 8:331.
A couple of months ago, I wrote a post about some of the different ways exercise can be beneficial to your health and wellbeing, independent of the old “calories in, calories out” adage (you can read it here, under the post titled “Feel the Burn”). Exercise is so much more than a way to burn fuel. As a brief recap, exercise can:
Facilitate growth of your musculoskeletal and cardiovascular systems
Improve cognition, attention and memory
Improve symptoms of anxiety, depression, and other conditions
People have known for millennia that exercise is good for you, but only relatively recently have the specific mechanisms of physical activity’s benefits to the body begun to be studied in a rigorous and controlled scientific manner. Earlier this year, an exciting study was published showing that exercise changes more than just the composition of your muscles and bones- it can actually change the composition of the gut microbiota (1). The “gut microbiome” is simply a fancy term to describe the hodge-podge of bacterial critters residing in your digestive system. And if you think there are only a few of these little bacteria inside you, think again. We now know that there are 10 times more of these microbiome bacteria than there are human cells in your own body! In other words, if counting cells is the only parameter to consider, then you are more bacterial than you are human- weird!
In this study, 34 sedentary adult volunteers participated in an endurance-based exercise training program for 6 weeks, without changing their diets or any other lifestyle factors1. The researchers took samples from the participants before and after the exercise program to analyze the composition of the gut microbiome. Amazingly, they found that just 6 short weeks of exercise significantly changed the levels of different microbes in the participants’ guts. However, after stopping the exercise program for 6 weeks and returning to a sedentary lifestyle pattern, the gut microbial composition of the participants went back to baseline, suggesting that exercise itself may have been causing the microbial changes.
You may be asking, “So what?” What does it mean for the composition of the gut microbe to change, and why should we care?
Although there are many aspects yet to be discovered, one of the reasons is that some of the microbes that increased with exercise are thought to have an anti-inflammatory effect in the gastrointestinal system. Managing inflammation is important for treating disease as well as promoting overall wellness, as excessive inflammation has been associated with impaired mood, digestive troubles, general malaise, and other problems.
Of course, this human study doesn’t prove that exercise reduces inflammation via its effect on the gut microbiome. To investigate this topic more deeply, the researchers turned to a mouse model so that they could experimentally manipulate both the exercise conditions as well as the microbiomes. And that’s just what they did in a follow-up study published this year (2). First, the researchers allowed one cohort of mice to run on a running wheel for 6 weeks (simulating endurance-based exercise for humans) but kept the other cohort of mice sedentary. Next, the researchers isolated the gut microbes from both of these mouse cohorts and implanted the microbes from these “donor mice” into “recipient mice” who did not have gut microbiomes of their own (learn more about these “germ-free” mice here: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4814450/) Finally, they induced intestinal inflammation by exposing the recipient mice who had received the “microbiome transplants” from either the Runner Mice or the Sedentary Mice to a chemical known to cause colon inflammation (aka acute colitis). Surprisingly, they found that the “Runner microbiome transplant” mice had reduced colon inflammation compared to the mice that had received the “Sedentary microbiome transplant”! This provided them strong evidence that exercise’s effects on the microbiome can have a direct effect on the way the body responds to inflammation-causing stimuli, and microbiota from Runner Mice seemed to have a more beneficial effect on reducing inflammation than microbiota from Sedentary Mice.
Although more research needs to be done, what we know so far from these two studies is:
Exercise can change the composition of the gut microbiome in humans.
Exercise promotes changes in the microbiome that are correlated with reduced inflammation.
For me, this was impressive motivation to stay consistent with my exercise routine, since I want to keep my gut microbes happy and healthy! These studies also made me feel empowered, because they reminded me that we have so many tools up our sleeves to improve our health and wellness. Exercise is just one of those many tools, and we now know that it may help to reduce inflammation throughout the body by changing your microbiome.
Next time you work out, think about your billions upon billions of gut critters and how you are doing something to help them help you!
Learn more here:
Allen J., Mailing, L., Niemero, G. et al. Exercise alters gut microbiota composition and function in lean and obese humans. Med Sci Sports Exerc. 2018 (50:4). https://www.ncbi.nlm.nih.gov/pubmed/29166320
Allen J., Mailing, L., Cohrs, J. et al. Exercise training-induced modification of the gut microbiota persists after microbiota colonization and attenuates the response to chemically-induced colitis in gnotobiotic mice. Gut Microbes 2018 (9:2). https://www.ncbi.nlm.nih.gov/pubmed/28862530
As a PhD student, I spend a lot of time thinking about the concepts of diagnostics related to mental health conditions. Google defines diagnostics as “the identification of the nature of a problem by examination of symptoms.” For example, imagine you bump your leg against a table. A few minutes later you look down and there’s a purple splotch on your leg where you bumped it. Diagnosis? You have a bruise.
Not everything is as simple to diagnose as a bruise, but the same model generally applies even to the far more complicated things. Take the diagnostic criteria for Major Depressive Disorder (MDD), for example. In order to be “officially” diagnosed with MDD, you must have a combination of at least 5 of 9 possible symptoms, which include loss of interest in things, depressed mood, changes in sleep or appetite, etc1. Of those 5 symptoms, at least one must be either loss of interest or depressed mood. You can have all 9 symptoms, or you can have just 5 or 6. To me, this diagnostic criterion sounds just like a word problem or logic puzzle my teacher would have given us in a high school math class: “How many different combinations of symptoms can patients have and still be diagnosed with the same disease?” (Bonus points if you actually solve that problem. Hint: It’s a big number!)
Now throw in the added complication that most of these symptoms are not directly “measurable” and are mostly based on an individual’s subjective take on his or her experiences. There’s no blood test to see if you’re depressed, or having intrusive body image thoughts, etc. Obviously, diagnostics in the realm of mental/emotional health has a long way to go, and there are a ton of really smart, passionate scientists and doctors working hard to figure out better ways to diagnose these conditions so that people can get the best care possible. But, while I do believe that even the diagnostics we have now can be powerful and helpful, both to doctors and their patients, I think there is plenty of space for individuals struggling with eating or body image concerns to move toward a more holistic view of mental health and wellness. In part, this involves seeing diagnostics for what it is: one of many tools doctors can use to help people get the care and support they need. With that in mind, here are a few examples of how we could take thoughts we may have had before, and transform them into something more beneficial/empowering:
So next time you are thinking about where you currently stand on your personal wellness spectra, remember:
Diagnoses are just tools. They are not value judgments on whether you “deserve” help or extra support.
You know your brain and body better than anyone- it’s totally okay (and empowering even!) to advocate for your own health and wellness. There is NO SHAME in asking for help (whether from medical professionals or family/friends) if you feel you are struggling with body image, less-than-ideal eating habits, etc.
Stick it where the sun don't shine
Our bodies and bathing suits
It’s summer, which means it’s bathing suit season. It seems like there are memes EVERYWHERE about people dreading wearing bathing suits. Pinterest is teeming with those dangerous and misleading “how to lose X pounds and get bikini-ready in 3 days!” posts. Social media in general is overflowing with images (many of which are photoshopped) of people in itty bitty bikinis. For me, summer can be a particularly triggering season for my body image/eating struggles. There are bodies on display all over the place, and it can be very hard not to compare my body’s aesthetic to someone else’s. It’s so easy to create a mental fantasy about how wonderful your summer, and your life, would be if you could just have the “perfect bikini body”.
I hate to admit it, but sometimes I have let my feelings of discomfort/dissatisfaction with my body dictate whether or not I participate in events, especially those that involve wearing bathing suits. This past weekend, I was given the opportunity to help supervise a children’s swimming class for an organization that I volunteer with. The organization needed volunteers to help ensure that all of the kids were safe and having a good time, which sounded like the perfect way to spend my Sunday afternoon. Until…I had to put on my bathing suit. I pulled out the only one-piece suit that I own, slipped it on, and looked in the mirror. Without a moment’s hesitation, my inner critic unleashed a massive tornado of negative self-talk and began to chastise every single inch of my body. I could literally feel myself withdraw inward, as though trying to hide from the mirror and from my mean, irrational inner voice. I started to take the suit off and conjure up fake excuses for why I couldn’t go to the pool to volunteer. “I’m not feeling well, I think I’m coming down with something and don’t want to get anyone else sick.” “Something came up at work and I have to go in unexpectedly.” “My family really needs me for something urgently.” Let’s be honest for a minute, we’ve all used these. I’ve used them more times than I care to admit on days when I’m having a particularly “bad body image day” to avoid work, activities with friends, dates, even time with my family. Today, I just had to pick one out of the proverbial excuse bag and it would be over. No harm, no foul, right?
But a moment later, seemingly out of nowhere, another “voice” began to pipe in and challenge my inner critic. Timidly, it said, “Wait a minute, just think about all of the experiences you’ll be missing! Think of all those adorable kids wanting to play with you. Think of how you can make them smile and laugh. Maybe, just this once, don’t listen to your inner critic. Tell her to stick it where the sun don’t shine and show up for those kids!”
And so I did! I packed up my towel, got in my car, and drove to the pool where I proceeded to have an absolute blast swimming and splashing around with a bunch of awesome kiddos. It’s not that my inner critic ever went completely silent– in fact, she kept up her nasty diatribe for most of the time I was there. But what was more important to me was that I showed up anyway. This time, I refused to let that inner critical voice keep me from an opportunity that was valuable to me and made me smile. I know that my inner critic will probably keep bugging me about bathing suits and beach days and pool parties, but that’s okay, because I get to choose when I want to show her who’s boss!
I wish I could go back and experience all the things I avoided because of body image-related reasons. But since time travel is not yet available (darn!), I will instead make a commitment to not deprive myself of any more experiences just because of the way I am feeling about my body. I will not hide or withdraw. I will tell my inner critic to stick it where the sun don’t shine and will show up, even when it’s hard or uncomfortable. And most importantly, I will always keep trying!
What experiences have you had where you told your inner critic to “stick it where the sun don’t shine” and went on living your best life?
What commitment can you make to yourself to not let your inner critic’s judgment of your body or appearance stop you from partaking in experiences that are meaningful/enjoyable for you?
Feel the burn!
For decades, exercise has been sold to women by the media as a way to burn calories and get slim. Basically, it’s been all about maximizing energy expenditure and achieving some particular physique goal. Take a moment and think about how the media portrays female fitness. What comes to mind? A group of neon leotard-wearing women doing hundreds of boring leg lifts on a VCR from the 80s? A Pinterest ad promising that you’ll “torch 1,000 calories in 1 hour” with some hot new at-home workout? A young woman running for miles to “burn off” the dessert she had with lunch?
I have a huge issue with this outdated portrayal of female fitness, from both a personal perspective and a scientific one. Personally, I find this representation to be both objectifying and belittling. However, the scientist in me cringes for other reasons. Portraying fitness as just a tool for burning calories short-sides all of the other incredible benefits of exercise.
Exercise does so much more for your body than burn fuel (aka calories). You probably already know that physical activity is good for improving strength and endurance, building healthy bones and connective tissue, and warding off many chronic conditions such as heart disease and diabetes. But have you ever thought about the ways working out benefits your brain? Here are just a few examples from recent neuroscience research about how awesome exercise is for your brain:
Aerobic exercise improves cognition, attention, and memory (who doesn’t want better attention and memory come test day, right?!) (1)
Exercise can reduce inflammation in the brain (2).
Exercise can help your brain make new neurons as well as connections between neurons, called synapses (1,3).
In many cases, regular exercise can be just as effective as prescription medicines for treating anxiety and depression (4) (Yep, you read that correctly!)
Yes, exercise does require your body to expend energy. But exercising just to burn calories is like driving your dream car around town just to use up gasoline. If you don’t think of cruising around with your windows cranked down and music cranked up as just a way to burn fuel, then why should you think of exercise as just a way to use up calories?
The ability to use and move your body is both an amazing feat of biology and an incredible privilege. When you work out in ways that you enjoy, whether you’re hitting up an intense Zumba class or setting a PR for bench press, you are not only improving the general wellbeing of your body, but you’re also making your brain stronger, healthier, and more resilient. So next time you lace up your running shoes or load up your barbell, I hope you feel the burn. Feel the burn as you torch stress and anxiety, fire up some new neurons and synapses, and light up your cognition and memory. And as a hot added bonus (yes, all puns intended), you’ll be burning down stereotypes about female fitness every time you work out to do more than just burn calories.
Learn more here!
Dietrich, K., Bastl, A., Wersching, H. et al. (2017). Effects of different exercise strategies and intensities on memory performance and neurogenesis. Frontiers in Behavioral Neuroscience, 11.
Cotman, C., Berchtold, N., & Christie, L. (2007). Exercise builds brain health: key roles for growth factor cascades and inflammation. Trends in Neurosciences, 30(9), 464-472.
Voss, M., Vivar, C., Kramer, A., & van Praag, H. (2013). Bridging animal and human models of exercise-induced brain plasticity. Trends in Cognitive Sciences, 17(10), 525-544.
Herring, M., O’Connor, P., & Dishman, R. (2010) The effect of exercise training on anxiety symptoms among patients- a systematic review. JAMA Internal Medicine, 170(4), 321-331.
You're so vain...not!
A common stereotype about individuals with anorexia nervosa (AN) and other eating disorders (EDs) is that they have more vanity than the average person. We tend to think that people with AN are only driven by a deep desire to craft an extremely thin physique, but this is just not true. AN is far more than a desire for a particular appearance. In fact, many people with AN actually have differences in the way their brains process body size, even at an unconscious level!
To think about this, consider the act of walking through a doorway. If the doorway is much wider than you, you just glide through without giving it another thought. What about a doorway that’s a little smaller? Before you go through, your brain does a calculation to compare what it perceives as the door’s size to what it perceives as your body’s size, and makes sure you’ll fit. If it thinks you will fit, you once again walk right through. But what if the doorway is too narrow, like a door to an attic or tiny closet? This time, you’d turn your shoulders and torso sideways to make yourself narrower so that you could fit. But of all the wide or narrow doorways you’ve walked through so far this week, how many did you consciously think to yourself, “If my body is this big, and the door frame is this wide, then I have a 100% chance of fitting through the door without the need to turn my shoulders.”? If you’re like me, that thought probably popped into your head a whopping zero times. This means that our brain makes this “me vs. door” size comparison unconsciously, making it a really creative tool for studying how our unconscious brain perceives our body’s size.
Scientists thought about this and asked in a research study how people with AN handle this so-called Doorway Dilemma (Keizer et al.). They had participants walk through a doorway, which the researchers changed the width of between trials without the participants’ knowledge. They found that women with AN started to rotate their shoulders to “fit” through much larger doorways than the women without AN. This means that the women with AN viewed their bodies as larger than they really are, even subconsciously!
So, what can we learn from this really interesting research?
Many people with AN have differences in the ways their subconscious brains process their body size.
While many people with AN and other EDs do have severe body image concerns, this is definitely not the only thing causing their disorder.
People with EDs are NOT vainer than others. Webster’s definition of vanity is “excessive pride or admiration of one’s own appearance or achievements.” I’d say a difference in subconscious brain processing of body proportions is VERY different than this definition of vanity!
Now, time to reflect:
What stereotypes do you personally hold about people with eating disorders?
How do these stereotypes affect how you treat people with EDs?
Can you use this new knowledge to show more compassion to people struggling with EDs, or perhaps even to yourself?
And in case you were interested in learning more about the Doorway Dilemma study, here is the full citation:
Keizer A, Smeets MAM, Dijkerman HC, Uzunbajakau SA, van Elburg A, et al. (2013) Too Fat to Fit through the Door: First Evidence for Disturbed Body-Scaled Action in Anorexia Nervosa during Locomotion. PLOS ONE 8(5): e64602. https://doi.org/10.1371/journal.pone.0064602