Public speaking, your brain and glucose
A few years ago I wrote a popular post on your brain and glucose: today I’m updating it, and giving you some of the research into how to fuel your brain, and what not to do.
A question for you: when you get really hungry, do you find your thinking seizes up? Or if you’ve been working for a couple of hours, that you slow down and find it hard to focus? Most people do. Hunger also tends to make us more impulsive or snappy.
I used to think this was about my body’s need for energy: I never joined the dots and connected it to my brain until I read some research. Apparently the brain accounts for about 2 percent of our body weight but chews through roughly 20 percent of our daily calories, drawing it up from the liver as needed. And any type of mentally challenging activity needs extra glucose. (But glucose of a certain kind and in the right doses – more on this below.)
Some research. Clients often talk to me about being unable to think clearly or stay coherent when people are looking at them. This is very common (and usually worse for introverts), and there are always different factors which impact our mental agility in front of groups – from self-consciousness to full-blown panic…last-minute preparation, or not being on top of our subject matter. But we don’t always consider getting the right amount of metabolic fuel! Brain functions like thinking, memory and learning are closely tied to glucose levels and how efficiently the brain uses this fuel, according to The Harvard Mahoney Neuroscience Institute On The Brain newsletter.
Studies have been done into the connection between glucose and self-control – and you need self-control when you’re speaking to a group, using it for things like focus and interacting with your audience. Dr Roy Baumeister of Florida University talks about the limit to our resources for things like impulse control and making decisions. Baumeister says that when we make one difficult decision, the next becomes even more difficult. And of course speaking in public often requires split second decisions.
The more recently evolved areas of the brain like the prefrontal cortex (the higher thinking part), are particularly sensitive to falling glucose levels, while lower level, older parts are more resilient, Leigh Gibson of Roehampton University in the U.K. Gibson says: “When your glucose level drops, the symptom is confused thinking”.
When you present, you’re juggling a lot of balls at the same time:
- You’re processing a lot of information in a short space of time
- You’re trying to stay focused and not be distracted by what else is happening in the room
- You might also be trying to suppress your fears and concerns – about who’s in the audience, what they think of you, how well or badly you’re doing
- If you’re a nervous speaker, you may be battling your natural desire to flee the scene! (the flight/fight syndrome) – and each time we inhibit an impulse, our capacity to inhibit for the next event reduces, as Baumeister mentions above (this is why our self-control tends to weaken as the day goes on)
- You may need to make decisions in the moment, such as during Q and A – ‘what’s my best/most intelligent response to that awful question?’
While we’re doing all this, our brains use a lot of fuel; they’re like a battery which drains quickly if it’s not topped up.
What should we eat or drink? So what should we eat/drink to refuel and feed our brain? A large chocolate muffin or can of soft drink before we get up to speak? Well no! Unless you’re desperate. And certainly, prolonged use of simple sugars actually makes your thinking more confused and ineffective. The bad news is that sugary food not only spikes our blood sugar, but also elevates our cortisol stress hormone, which obviously doesn’t help any anxiety you’re feeling.
So the solution is to have some low GI food. Protein is good: meat, dense bread, or fruit such as a banana or berries (check that the fruit is low GI).
Even if you’re one of those people who doesn’t feel like having breakfast or eating anything before you present, hopefully you can now see that’s it’s worth making sure that your brain has enough to run on – or you might run out of fuel during your presentation.