How Does Stress Affect Our Weight and Health?

effects of stress fight or flight overeating parasympathetic nervous system stress sympathetic nervous system weight gain yoga

By Florencia Tagliavini, Nutritionist

Stress can physically affect our digestive, nervous and hormonal systems. It can lead us to comfort eating or binge eating as well, negatively impacting our metabolism.

The Stress Response

The stress response is absolutely necessary in our bodies and has a purpose. In prehistoric times, when man was faced with a life-threatening situation such as big animal, the body automatically went into survival mode, aka "fight-or-flight" response. This mechanism allowed people and other mammals to react quickly by provoking a whole cascade of stress hormones that produce various physiological changes:

  • Heart races
  • Muscles tighten
  • Pupils dilate
  • Breathing rate increases
  • Blood pressure increases
These are just some of the changes that occur in order to fight or flee from the present threat.

 

Now, in our current life we are not faced with dangerous animals we have to run away from, but we are faced with environmental stressors at a lower level and on a more ongoing basis such as a demanding job, a busy household, relationship strains or simply traffic jams, or the anxiety and constant worry about pretty much anything. This is known as chronic stress, which is much less traumatic than a car accident or a life-threatening situation but unfortunately still triggers the same stress response/survival mechanism. Our brain cannot differentiate between a life-threatening situation and chronic stress so when we are stressed, we have muscular tension, high blood pressure, an accelerated heartbeat and many other effects on a regular basis which can put us at risk for many health problems.

Our autonomic nervous system has two opposing systems:

Sympathetic nervous system: which is responsible for the fight-or-flight response and the whole cascade of reactions that go along - one of them is putting digestion on hold as all the energy has to be concentrated at the task at hand: survival!
Parasympathetic nervous system: which is responsible for the relaxation response and where the body is concentrated on digestion so a whole different set of hormones and reactions are at work here.

How does stress affect specifically our weight and metabolism?

We all have probably experienced comfort eating. When we are sad or down for whatever reason and pick up that chocolate that makes us feel good or sit down and eat a whole container of ice cream. Right?

This has to do with this whole survival mechanism. We are designed to live in homeostasis or balance. Our bodies have so many different mechanisms to deal with various issues at hand including bringing stress down. The release of cortisol (stress hormone) can also affect hormones that increase appetite. As soon as we start eating (salivating, chewing and swallowing) we activate the parasympathetic system responsible for the relaxation response or the rest-and-digest response and therefore stopping the fight-or-flight response with all its cascade of reactions and we momentarily feel good, until we finish the whole bucket of ice cream.

Notice that you don't pick up a carrot or a healthy snack but something typically with lots of sugar, fat and/or calories. The theory is that our body needs lots of calories and energy for this life-threatening situation and the intake of this type of food tells our brain to stop releasing the cortisol hormone so we can go back to balance.

 

Another effect of the stress response is that our body is bathed with glucose (hormones increase fatty acids circulation and break down protein in order to obtain more glucose/fuel from these sources) because we need all the fuel we can get for this fight-or-flight situation. The downside is that the fuel that is not used is then stored as fat. The catabolism or break down of different fuel sources can also slow down our metabolism.

 

In summary, stress can cause us to overeat unhealthy foods while also slowing our metabolism and storing fat in our bodies. This mechanism makes it hard for some people to control their weight and can affect us emotionally as well.

Stress generates a cascade of many physiological changes that affect our body. Over time, repeated activation of the stress response takes a toll on the body. Stress is one of the key risk factors of many of the chronic diseases that are on the rise today such as cancer and cardiovascular disease.

What can we do?

We need to learn how to manage stress. There are many techniques to do this such as deep abdominal breathing, focus on a soothing word (such as peace or calm), visualization of tranquil scenes, repetitive prayer, yoga, meditation, tai chi, etc. Other activities that can also activate the parasympathetic system could be exercise, listening to music, playing an instrument, drawing or painting are just some examples. Different techniques or activities work for some people but not for others, try various strategies and find what you connect with and works for you!



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