Sugar, cortisol, and me

As exam season looms, revision advice is a common topic of interest for a lot of students coming to Academic Learning Support one-to-one sessions. We tell them they need to ‘look after themselves,’ and this has to include eating properly, but what does that mean, and is there a diet that can improve their revision rather than just keep them going?

Well, there’s a course for that – Nutrition for Peak Performance, which I attended last week. I’ll be passing on the wisdom below to students, but I’ve found it quite useful myself.

If you’re stressed (e.g. if you’re revising for exams) and if you’re not eating properly, that can cause:

  • ‘Fuzzy brain’
  • Poor concentration
  • Energy drops after eating
  • Hunger & sugar cravings
  • Fat around the middle

A lot of these can be related to the actions of cortisol.

Cortisol is the body’s master stress hormone, relating to mood, motivation and fear, and is released as a response to stress, alongside adrenaline. It takes a few minutes to have an effect, but it diverts energy away from the immune system, starts sugar cravings, increases blood pressure and halts digestion. It also takes any excess glucose created by adrenaline and stores it as fat, usually around the stomach.

A certain level of stress is helpful in exams, as it helps students think faster and work more quickly. However, if stress is constant and the cortisol level doesn’t drop, this can cause anxiety or depression, headaches, heart disease, weight gain, and problems with memory, digestion, and sleep. Eventually the reserves of both cortisol and adrenaline become exhausted, leading to a ‘wired but tired’ feeling.

One of the ways you can address this is through food, glorious food. First, a couple of old friends.

Sugar is incredibly addictive. Cortisol release stimulates sugar cravings, and sugar causes dopamine to be released – which is why we turn to sweet things when stressed. However, sugar makes the dopamine receptors in your brain less effective, so you crave more. Cutting out sugar will flatten out the peaks and troughs and make your energy more constant throughout the day. Also, tastebuds recycle every 10-14 days, so if you go 10 days without sugar (2 portions of fruit a day), you will taste how incredibly sugary your usual diet is. I’m five days away from finding out if this is true. Five more days with no biscuits, chocolate, cake or even ketchup.

Caffeine stimulates the release of dopamine, cortisol and adrenaline and so causes all the problems above. Which means that if you have a coffee and a pastry for breakfast in a stressed state, you get a massive sugar rush from the adrenaline release and the sugar from the pastry. Yum yum. However, the cortisol takes the excess glucose from your bloodstream, so you soon get an energy dip and a craving for more sugary food. However, for me, cutting caffeine out would be crossing a line. I’ve reduced it a bit but I will never, ever give up coffee.

Protein is very important because it is used to create adrenaline and cortisol, and so can top up those reserves. It creates many other useful enzymes, hormones and body chemicals along with muscles (which can store and use excess glucose). Have some with all meals, if possible.

You need fat as well – specifically Omega 3 and 6, which you can also get in oily fish (including trout and salmon), eggs, flat seeds, and walnuts. It helps neurotransmitters to function.

Meals need to be balanced to get the full benefit. They should be 50% vegetables, 25% protein, 25% carbohydrate (especially complex carbs like rice and potatoes). You should be eating 5-10 portions of fruit and veg a day (and only 1 portion of fruit to each 4 of vegetables).

For example, porridge with nuts and seeds and a few blueberries will add plenty of protein to your breakfast. Adding a little cinnamon will help to regulate your blood sugar. Smoothies for breakfast are fine, but they need to be 4 parts vegetables to 1 part fruit. Add some nuts and seeds too, plus some protein powder if you want.

I suppose the question in the end is, ‘is it worth it?’ Well, I’ve been following the above advice for six days and I have got a bit more energy, and it’s certainly more constant. However, giving up sugar has been really difficult, especially in perfect ice lolly weather. On balance, though, I’m going to keep it going.

I know there’s more to say about this – biochemistry isn’t really my area – so if you’d like to add something, please leave it below.



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