Stress is defined as being “subject to tension or pressure”.
Stress is not necessarily a bad thing. It can be an essential stimulus for adaptation and performance. Our physical training needs to create a big enough mechanical and metabolic stress to drive the adaptations that make us fitter, faster, stronger. And, across life, feeling ‘pressure’ to perform can sharpen our focus helping us excel at the task in hand.
Apply pressure, but are not so big we are pushed too far or overwhelmed (physically or mentally);
Are time limited, i.e. do not persist indefinitely; and
Are recoverable, i.e. we have the time and resources to recover from them.
The problem comes when one or more of these things is missing. Extended periods of pressure, demands that stretch us beyond our capabilities, and / or challenges that we perceive no benefit from.
As already alluded to, stressors can be physical (e.g. training) or psychological. In this blog, we are focussing on the psychological, how they might impact appetite and hunger, and why. From ‘stress eating’, to loss of appetite, to the foods we might crave when feeling ‘stressed’. As ever when it comes to our bodies, there is quite a lot going on!! And we don’t yet have all the answers. But, here goes …
The Info …
Stress Hormones …
Psychological stress can come from many directions. Pressure to perform at work or in the sports arena (which can be one and the same thing for athletes!), financial concerns, issues at work, family life, travel, future uncertainty, and disrupted routines are just
Short term stress drives the release of adrenaline and associated hormones. It is the classic ‘fight or flight’ response. These hormones cause a suppression of appetite, and an increase in blood sugar. Evolutionarily this makes sense … appetite is not important when you need to fight or flee from a sabre tooth tiger, but having enough readily available energy to do this is (aka blood sugar)!! This is why when something stressful suddenly happens you will typically never notice being hungry, and will feel a surge of energy.
When stress lasts more than a few hours we start to move away from this ‘acute’ stress response to a ‘chronic’ stress response, driven by the hormone cortisol. Cortisol does several things that have the potential to impact our appetite and food choices … aka how our diet responds to our stress!
First, cortisol triggers the release of a hormone called ghrelin that makes us feel hungry. Interestingly, it is a mixed bag with how much people eat when chronically stressed. Many people eat more, and ghrelin may be part of the trigger for this. But some people eat less. So, ghrelin isn’t the whole story!
Food Preferences …
Regardless of whether you are someone who eats more or someone who eats less when stressed, it has been shown time and again that we are more likely to reach for hyper-palatable high sugar and high fat foods when stressed.
There are multiple factors that likely contribute to this.
Increased impulsiveness: Stressful situations often require significant self-control, inhibition and focused decision making. This can impair our ability to make rational decisions outside of the stress, leading to more impulsive behaviour in other areas … such as eating.
Heightened reward responses: Stress can heighten our sensitivity to reward, meaning we get more pleasure than normal from things like hyper-palatable foods.
Blood sugar and cortisol: Increasing blood sugar by eating high sugar foods can reduce circulating cortisol levels, and so stress.
Insulin resistance: chronic cortisol can lead to some level of insulin resistance, which makes it harder to use blood sugar for energy, and means we need more sugar to trigger the same ‘reward’ response in the brain (even if it is heightened through stress once we get there).
And you can see how it is quite easy from this to end up in a cycle of eating hyper-palatable foods, or to trigger a habit of always reaching for hyper-palatable foods when stressed. As they have an immediate ‘reward’ on how we feel.
And Adding to All This, Sleep …
Stress doesn’t act alone! We know stress often impairs sleep. And sleep and nutrition are also in a close relationship. Sleep affects diet. And diet affects sleep. This is a whole topic itself (blog coming!), but it is worth noting that, like stress, impaired sleep also drives increased desire for high sugar foods, can reduce insulin sensitivity and increase the ‘reward’ response from food. So it seems lack of sleep has the potential to exacerbate the food stress response.
And The Gut …
We know that stress can impact our gut. We can feel sick, or have an upset stomach when we are stressed acutely or chronically. Long term, if we are not digesting and absorbing our food effectively we might be at increased risk of micronutrient deficiencies or getting enough energy to support our health and performance. So this is also something to be mindful of – particularly as we know low energy (calories) can also increase cortisol (stress) levels ….
A Point on The Research and Athletes …
It is worth noting that most research in this area has been performed on overweight or obese sedentary individuals. Athletes and athletic individuals do work slightly differently … metabolically and physiologically. So research is definitely needed in these populations to understand more … particularly as high level athletes are often under significant pressure to perform, combined with the physical stress of training, and specific dietary needs to support optimal health and performance.
What can we do? …
For reasons that extend way beyond nutrition, we want to manage stress in our lives to a level that is beneficial. If we are thinking pure sports performance, studies in strength, gymnastic and endurance sports have shown enhanced performance when athletes feel less stressed. And we know there are broader health implications of chronic stress. Realistically it is not always possible. However, tools that might help include meditation, mindfulness, having a support network, journaling, and prioritization. Exercise is also a tool for stress reduction, however this is less applicable to an athlete or individual who already trains multiple times a week … in fact, for competitors it can be a source of stress!
Nutrition wise, knowledge is power. Understanding our desires and behaviours in response to stress might be enough. We might not need or want to change our response, we might simply want to understand it. If so, hopefully this blog has gone some way towards that.
Remember there are no ‘good’ and ‘bad’ foods … a high sugar high fat food is not bad, this is simply a statement about what it contains! But it may be that you do not want to eat these over and above other foods, especially not repeatedly when stressed if stress is a constant in your life right now and / or you have certain health, performance or body composition goals, for example as an athlete.
It may be that for, understanding is also enough as by understanding the desires and behaviours you can rationalize them and avoid them. But if it is not, some practical strategies you could consider …
If you know that you reach for the biscuit tin when stressed and do not want to, set your environment up for success:
Meal prep dinners if you know that if you reach the end of the day stressed you will otherwise choose something that is high fat high sugar. This reduces the effort in making nutritious choices.
Don’t keep hyper-palatable foods in the house, or at least keep them out of sight. This reduces the opportunity.
And consider your eating behaviours:
Serve out portions of your hyper-palatable foods when stressed, rather than taking the whole box / tin / bag with you to snack from. You can always go back for more.
Allow yourself to eat a hyper-palatable food, but consider pairing it with something that is high protein and high fibre, so that you have something that keeps you feeling fuller and with more sustained energy for longer. Reducing the chance of one slice of cake becoming a whole cake, unintentionally.
The field of Intuitive Eating may also be something you want to explore. Intuitive eating means eating when you feel hungry and stopping when you feel full. This does not mean sitting down and eating everything you want whenever you want it!! It is about becoming – for want of a better word – in tune with your body’s needs and recognising the signals it is giving you. It is something that takes time to learn and become good at … just like any skill. But something to consider. I have included two podcasts by an expert in the field in the ‘Where to find out more …’ section below, if you want to learn more.
So there you have it. A little of what we think we know about stress and nutrition. And some things to consider in terms of responding to it!
Get in touch to chat more about this, or any aspect of nutrition with me :)
Where to find out more …
Articles, reviews and podcasts that have informed this blog, and / or that provide more extensive consideration of the topic or dealing with stress and nutrition include:
Masih and colleagues’ 2017 review: ‘Stress-induced eating and the relaxation response as a potential antidote: a review and hypothesis’ in the journal Appetite
Yau and Potenza’s 2013 review: ‘Stress and eating behaviours’ in the journal Minerva Endocrinology
Harvard Mental Health Letter from 2012: ‘Why stress causes people to overeat’
RP Podcast Episodes 196 and 197: Intuitive Eating, with Mike Israetel and Gabrielle Fundaro