Can Stress Cause Weight Gain?

Can stress cause weight gain?

Questions like the one in the title of this blog are really common in the health and fitness space, but while they are completely valid and understandable, they aren’t quite complete and so any answer given may not really provide what the asker was looking for. That’s because this question is really two questions kinda mashed into one, which are:

  1. If I’m stressed, will this cause me to gain fat?
  2. Does stress make me more likely to gain fat?

These seem interchangeable but there is a subtle difference. The former implies that stress on its own alters your physiology somehow, causing the accumulation of body fat, while the latter simply asks whether stress changes some external factors that may change your behaviour.

Answering these two independently should allow me, in this blog, to fully demystify the means by which stress may or may not impact the amount of body fat that you store. Let’s start with the first question – does being stressed cause you to gain fat by itself?

The reason many will say this happens is that cortisol (one of the hormones involved in your body’s stress response) is elevated in people with Cushing Syndrome, and these individuals store more body fat around their midsection. In non-clinical situations, however, when cortisol is raised because of stress rather than a condition, cortisol is not likely to meaningfully increase your central fat storage, nor can it cause fat gain in general.

The only thing that can cause fat gain is still a calorie surplus.

Cortisol can, however, bind on to receptors for another hormone called aldosterone. Aldosterone’s job is to retain water during times of dehydration, and so stress can cause a temporary gain in scale weight all by itself. This will dissipate as soon as you chill out for a day or two, but can certainly be a barrier for some people. I’m sure you can see the vicious circle:

I want to lose weight

I get stressed and gain water weight

I haven’t lost weight

I get more stressed

I gain more water

I think I’ve GAINED weight

I get more stressed


This is one reason why, while they are useful, bathroom scales should not be your only progress measure. It is, however, the only way that stress per se causes weight gain, but we haven’t looked at point 2 just yet, and stress can dramatically alter your behaviour towards food for four very good reasons. I’ll look at each in turn, but quickly I’m first going to explain how stress ‘works’ because it’s important.

The stress response is an evolved action undertaken by your body to deal with threats. At all times you are in a state called allostasis, which basically means not stressed for the purpose of today. When you encounter a stressor, be that a bill, an argument with a loved one, or physical danger like being chased by a wolf, your body prepares you in the exact same way:

  • Increased alertness
  • Increased focus on the stressor
  • Heightened blood pressure and heart rate, allowing for rapid delivery of nutrients to your brain and your muscles if you need to fight something
  • Secretion of the aforementioned cortisol, as well as adrenaline and noradrenaline. The latter two help to increase heart rate and alertness, but all three also work together to increase blood sugar and blood lipids, meaning there is more fuel available for your body to use

After the stress response has been mounted you’re better able to deal with what you need to deal with and then your body is supposed to return to homeostasis, and it usually does. We do, however, live in a world in which we did not evolve with jobs, taxes, traffic and office politics to deal with. For some of us, this can mean this response is activated all the time to a low level, and the effects of this can be far-reaching as you will see. With that outlined, let’s look at how it can affect your eating behaviour…

First, whenever you want to eat something, you want to eat it because a subconscious part of your brain has presented you with the idea. It may not seem like it, but everything from cravings to simple eating desire related to smelling something delicious is completely out of your conscious control. A deep, primitive part of your brain nested within the limbic system presents the image of what it wants to the more evolutionarily recent frontal cortex – the home of your consciousness. Your conscious mind is then tasked with either deciding to eat whatever it is or exert executive control to dismiss the craving (however hard that is to do!). When you’re stressed, however, the signal from the limbic system to the frontal cortex is dramatically diminished – that’s because part of the stress response acts to heighten conscious awareness of the stressor (be that a danger, a bill, a job thing, a family thing, something else or a combination of things) to the detriment of your awareness of everything else.

This makes evolutionary sense – if you’re in danger of being eaten by a wolf, that is not the time to be distracted.

Because of this, the signal is instead sent from the limbic system straight to the motor cortex and you are instead aware of yourself figuratively following orders. Ever find yourself looking in the fridge when stressed without realising why, or driving towards work instead of somewhere else because you’re arguing with your partner? That’s why. This makes you far, far more susceptible to environmental food cues and cravings, so it’s really important to get into the habit of creating acute awareness before you eat. Ask yourself why you’re eating and if you really want to do it – has it been a conscious decision, or are you just following orders?

Next, we need to consider the anxiogenic (anxiety causing) nature of the stress response. Being stressed can make you anxious, alert, and hyper-vigilant, and that’s a really uncomfortable way to be. One of the ways that your body calms you back down after a stress response is with endogenous opioid secretion in the brain – an important thing because the stress response is pretty damaging to you if it goes on for too long. This process can, however, be hijacked by something pretty influential – really tasty food. If you eat something delicious this releases endogenous opioids, thus calming you down. Over time your brain can learn that food is the go-to thing to make you feel better and so as soon as a stress response is mounted, your primitive brain can present images of tasty food that will make you feel better…and I’ve already explained why being stressed when your brain wants something can be a bad thing. Managing this by being aware of stress-related desires to eat can be very useful for those that find themselves reaching for chocolate when work gets rough – alternative methods of achieving the same effect include exercise, social interaction (especially if it’s…intimate), spending time with a dog/cat or music. Whatever helps you de-stress will do the job, and it won’t derail your fat loss efforts in the process.

Next up, another brain chemical responsible for returning you to baseline after a stress response, called neurotransmitter Y, has two purposes:

  • It stops you being stressed
  • It encourages you to replace hypothetically lost energy

The stress response is, as I’ve explained already, an evolved process for dealing with threats that responds in the same way regardless of the threat. It initially evolved to help us deal with predators or similar situations of fight or flight, and that means it evolved to make you do very energy-expensive things. After an activity like that it’s really important to replace all used energy by eating a lot, otherwise, your escape will only be good until you starve to death. Unfortunately in the modern world that now means that after your stressful day at work you get back home hungrier. Being aware of this can be useful because it again allows you to properly assess whether you need additional food, or you just want it because you’ve been stressed.

In short, as you can see from the last three points, intra and post-stress mindfulness are highly valuable. Don’t allow your stress to control you and ask yourself what is driving you towards food/snacks.

Sure, they may make you feel better short term, but it’s crucial that you ask yourself what you really want to do – if you really want the food then that’s absolutely your decision to make – but if you know you’re going to be more proud of yourself tomorrow if you deal with the stress in a way that doesn’t undermine any fat loss or weight maintenance goals that you have, then you place yourself in a position to act upon that.

There is a multitude of things that will help you chill out a bit that you will almost certainly know already – you just need the presence of mind to choose them when your brain is crying out for an anti-stress packet of biscuits.

Finally, as mentioned, stress can lead to anxiety and hyper-awareness, both of which make for a busy mind. Busy minds can make sleep very, very difficult, and a lack of sleep leads to an incremental increase in appetite paired with poorer executive decisional making processes – not good! The best way to deal with stress-related poor sleep is to journal things – write out what is bothering you and write a to-do list for tomorrow. Really list out the things that you can do tomorrow to make some small yet meaningful progress towards solving whatever it is; this could be a tiny step towards a problem that seems insurmountable, or it could be a complete solution. It doesn’t matter. It just needs to be something that you can and will do, that will help. This lets you switch off your brain knowing that tomorrow you have a plan that you can and will act upon it, and things will move one increment towards better – it sounds like BS but you’d be amazed at how much of a difference it makes.

As a final point, it’s useful to note that stress is normal and natural in the modern world – things really are more stressful than they used to be with long working hours, busy social commitments and constant accessibility. Do not get stressed at how stressed you are! There are many ways to deal with stress itself – journaling as per the above is one, as is diarising your time to improve time management and eliminating wasted time as much as possible. After that, look after things and fix them before they break, take the time to understand your personal finances, and don’t ever be afraid to talk to people about it when life gets on top of you. The act of talking allows you to think more clearly as well as getting feedback from others, and is the best method we have for problem-solving.

Finally, be sure to take some time every day – be that 5 minutes or 5 hours, whatever you can spare – to do something for yourself that you enjoy and that you care about. The biggest lie we’ve been told is that we must be productive all the time; it’s not true. If you spend an hour per day watching Netflix that might be the thing that gives you enough of a break to get back to Carpe-ing the Diem tomorrow.

And taking that time is the least you owe yourself.

Listen to this podcast episode about stress with Dr Rangan Chatterjee

"All in or all out" Rachael is a vibrant, no-bullshit-talking Scottish nutrition geek and coach helping women to lose weight without giving up their confidence OR their favourite foods.

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