Why certain foods make us tired
We all know the feeling: you head out for lunch fresh and spry, only to return to your desk and struggle to keep your eyes open for the next few hours. While many think this is just part of the daily cycle – hey, those long stretches at work are not easy! – the reality is that if we are talking about a serious drop in energy, it is far more likely down to what you just ate for your midday meal.
In fact I’m sure none of this is a surprise to you. You know very well how different your afternoon energy levels are when you stick to a salmon salad and a glass of water versus, say, a large plate of pasta with a side of bread and a Coke.
Now just to add even more fuel to the fatigue fire, assume all of the unhealthy foods come with a sugary drink of some sort – be it artificial ice tea or juice or soda. It doesn't matter how much natural energy you were born with, if your meal of choice resembles anything that is grain-based and high in sugar and drinks that light up your brain’s pleasure centres, then you are soon going to crash – and long and hard at that.
The reason for this is fairly simple, of course. These types of foods that are more or less “made in a lab” cause our blood sugars to rise shortly after eating them. Now what goes up must naturally come down, and it is during those blood-glucose sugar free falls that your energy levels get severely sapped. The result can be a serious drop in both physical and mental capacity that can last hours.
Food choice and fatigue
At face value, it seems somewhat illogical that our mind and body become drowsy when we eat. After all, food is our fuel and calories should – in theory at least – give a boost to our energy levels. But there are foods that drive up our blood sugars have the exact opposite effect.
After food is ingested, glucose is released in the bloodstream, and in response the pancreas secretes insulin to push that glucose into your muscle and fat cells. Now if you have just overdosed on sugar and your blood glucose levels have been driven up dramatically, that insulin release is going to be more of an insulin spike, and it’s the start of a process that results in bad things for the body. There are many different examples we can refer to when it comes to how high glycemic index foods lead you to feel fatigued, so let’s pick just a few.
For starters, the more insulin we release, the more serotonin and melatonin that flood the brain. You’ll probably be familiar with both of these – serotonin being the “feel good” hormone (hence the sugar “rush” or “high”), and melatonin for its role as a sleep hormone (hence the drowsiness or the “crash”).
Studies have also shown another interesting connection between sugar and fatigue, which has to do with the link between our glucose levels and a group of brain cells called orexin neurons. These neurons produce a protein called orexin, which is essential for maintaining normal levels of “wakefulness” in the brain. The more our blood sugar spikes, however, the more those orexin levels are negatively affected.
Higher insulin levels also affect the branched-chain amino acids in our bloodstream relative to tryptophan (an aromatic amino acid) – which then allows tryptophan to receive “preferential uptake” by the brain. In the brain, tryptophan is converted to the familiar serotonin mentioned above, which is in turn converted to melatonin.
We could go on. There is indeed so much that could be written on the science of nutrition and energy levels. But the above is just meant to give you a very brief general overview of how the body can go into “sloth mode” if you consume too much of the wrong foods.
What to avoid and why
Sugar is a pretty obvious one, and we bring it under the spotlight with good reason: It is found in 75 percent of processed foods and hidden on food labels under 60 different names. But the other staple of the Western diet, grains, is just as bad. Everything from the cereals you eat for breakfast to the breads and pastas and rice you add to meals – these “bad carbs” will have a similar or same effect on your body’s blood glucose levels as would, say, that donut or chocolate bar or can of soda (if we are to get technical about the chemistry behind it all: Carbohydrates are organic compounds that contain sugar units, and sugar is in fact a carbohydrate).
Greasy fried foods are also worth a mention and should be avoided too. Fried chicken (or similar), for example, takes longer than most other foods to digest. Your digestive system literally has to work harder to break these foods down, and this in turn leaves your body with less energy for other functions.
Let’s now get back to sugar, though, and have a little bit of fun here by singling out some everyday foods that are chock-full of this stuff, and so are indeed worth steering away from if you wish to avoid the ups and downs:
- A can of soda: Starting with the obvious – and something very close to home here in the UAE where average soda consumption per resident is 300 cans per year (the fifth highest consumption rate in the world). One can of soda equals about 40 grams of sugar. You’ve just overdosed, and should find somewhere to lie down.
- A bowl of muesli: Watch out, because some of those big name brands will pump you with 20 grams of sugar or more if you eat just a small bowl. A seemingly healthy way to start your day? Don’t believe the marketing. And don’t be surprised if you are falling asleep on that commute into work.
- A Starbucks Frappuccino blended coffee: About 65 grams of sugar. Sorry, but ridiculous. Don’t expect the caffeine to give you any kind of “pick me up” with that amount of sugar overriding things. You’ll be lucky if you can even hold a conversation after consuming one of these.
- Protein bars: The perfect energy booster at any time of the day, right? Er, no. Some of these brands contain 30 grams of sugar – and many other nasty chemicals. Again, don’t believe the marketing machinery. These things won’t help you physically or mentally in any way. Exactly the opposite.
- Low fat fruit-flavoured yogurts: Oh dear, another food industry scam. Certain flavours from brands such as Yoplait contain close to 30 grams per container. These “snacks” are energy thieves, folks. And be warned: “low fat” foods are, contrary to what the name would imply, the perfect way to pack on the pounds.
Keep it simple
Speak to any disciplined Paleo eater and guess what – you won’t hear stories of mid-afternoon tired spells. There is no talk of a Red Bull-induced burst of energy followed by a period of “blah”. What a Paleo eater will tell you is that he or she has more or less balanced and consistent energy levels throughout the day – certainly as far as those energy levels relate to food choices.
This is because Paleo-type foods are all low glycemic index foods, meaning no blood glucose spikes, no insulin spikes – essentially, no carb highs and lows. And that’s really all there is to it.
So while the science behind how our bodies react to the wrong foods may be complex, the solution isn’t. Simply stick to whole, natural foods such as meats, eggs, vegetables, some fruits, nuts, seeds, and healthy oils, and maintain steady energy levels throughout the day – and a far healthier mind and body over the long term.
The opinions in the column are by Dr Graham Simpson, the Chief Medical Officer and Founder of Intelligent Health, a preventive medical centre located in Jumeirah, Dubai, and are not necessarily those held by Esquire or Hearst International.