You’ve just finished wolfing down your second helping of Thanksgiving dinner.
The next thing you remember is waking up on the couch…
What just happened?
Why do you get tired after eating?
Getting tired after eating is not unique to Thanksgiving. It can happen after any and even every meal. For many, fatigue after eating can seriously interrupt your life. Imagine having to fend off sleep every time you eat. Not fun!
In today’s post, we dive into why this happens!
Let’s get going!
No, it’s not the tryptophan
The reason you’re so tired after Thanksgiving dinner is that you ate multiple servings of turkey, right?
Turkey contains lots of tryptophan. And tryptophan, you’ve read, makes you sleepy. That’s not at all why you feel tired after eating turkey. Let me explain…
Tryptophan is an amino acid. Amino acids are the building blocks of protein. String 21 of the right amino acids together and you’ve built yourself a protein molecule.
The reason tryptophan is linked to tiredness is that it is a precursor to melatonin. If you’ve ever dealt with sleep issues, you’ve taken a melatonin supplement. Melatonin regulates your sleep-wake cycle. Low melatonin levels could be why you struggle to fall and to stay asleep. Ergo tryptophan consumption leads to melatonin production and that’s while you feel tired after eating turkey.
Nope. That’s not why. Tryptophan has little to do with why you feel tired after eating.
Tryptophan is not unique to turkey. You’ll find the stuff in every protein; whether it’s beef, pork, chicken, fish, or even rice and beans. The tryptophan levels in turkey really aren’t any higher than the tryptophan levels found in other protein sources. And if we’re being entirely transparent, tryptophan levels in any protein source are really quite small.
Your fatigue after turkey dinner is due to something entirely different than tryptophan…
Your brain on carbs
The human brain is a hungry beast. It weighs only 2 pounds, accounts for only 2% of your total body weight, yet uses 20% of all the calories you eat in a day. (1) The more you use your brain, the more energy (food) it requires. If you’re engaged in an intense chess match, your brain is going to need to eat more than if you’re binging the latest Netflix series.
For most of you, your brain receives its energy in the currency of glucose. You eat carbohydrates, your body digests said carbohydrates into little packets of glucose, and these glucose molecules make their way across the blood-brain barrier where they’re readily consumed by hungry brain cells.
If high blood sugars didn’t have catastrophic effects on humans, you could do quite well living on sodas, candy, and bologna. Alas, high blood sugars are disastrous for human health. That’s why your body comes equipped with a hormone known as insulin. Insulin takes glucose by the hand and leads it out of your blood (where it’s dangerous) and into your cells (where it’s useful and used for energy production).
The problem with carbs is that they can be a cheap source of fuel. Once insulin takes the glucose out of your blood and into your cells, your blood sugar drops. When you eat a huge serving of refined carbohydrates, your body overreacts by releasing too much insulin. The resulting effect is something known as reactive hypoglycemia.
Hangry? Read this
You likely know reactive hypoglycemia as being hangry. You just ate but you’re feeling both hungry, sleepy, and angry.
What’s going on?
Your body released too much insulin resulting in a state of low blood sugar. Now your brain starts screaming at you to eat again. While it’s waiting to be fed, you’ll experience a state of drowsiness. That drowsy feeling prevents you from doing something silly like going for a run while your blood sugars are low.
Feeling tired after eating has more to do with insulin than it does with tryptophan. But there’s more going on inside your cells than just insulin! Let’s dig into that next.
The real reason you get tired after eating – part I
You get tired after eating thanks to a phenomenon known as lipogenesis. Lipogenesis is a metabolic process used by your body to store energy as fat. (2) Here’s why lipogenesis is at the root of you getting tired after eating:
You’ve just finished a delicious dinner of pasta salad, mashed potatoes, chicken breasts, and a small slice of apple pie with vanilla ice-cream. Yum! All those carbs (the salad, potatoes, ice-cream, and pie) are broken down into three molecules:
About 80% of those carbohydrates you ate will end up as glucose. (3) And that’s a damn good thing because glucose is what your body uses as fuel. The fructose and galactose head on over to your liver where they’re either stored (fatty liver, anyone?) or converted to glucose to be used as fuel for a later date.
Your body then takes that glucose and puts it through a process called glycolysis. Glycolysis transforms glucose into a molecule known as pyruvate. It’s pyruvate that your mitochondria then take up to create ATP. Remember, ATP is the stuff your cells run on. Low levels of ATP = fatigue.
Depending on how many carbs your meal contains, you may have a surplus of glucose. By surplus, I mean more glucose than you need to perform a given activity. If your evening consists of binging the latest series, you’re not going to need much energy to do so. Thus, you’ll have an excess of glucose that has to go somewhere…
The real reason you get tired after eating – part II
You know what happens next. Through more chemical reactions, that excess glucose is transformed via lipogenesis into triglycerides and stored as body fat. This is a simplified overview of how your body either takes food and turns it into energy or stores the excess for a rainy day.
The process of making glucose from the food you eat and transforming it into stored energy is a heavily energy-dependent process. Meaning your cells are working incredibly hard and expending a lot of energy in the process. Lipogenesis takes a lot of ATP! This ATP is not going towards your energy levels. In fact, it’s taking that energy away!
Lipogenesis once in a while is no big deal. But should lipogenesis occur after every meal, not only are you going to gain unwanted body fat, you’re going to feel exhausted after eating. Too much energy is being spent putting glucose into storage. Now you know why you feel so tired after eating.
How to not feel tired after eating
When you eat a meal containing more carbohydrates than your body requires, the excess is transformed into body fat. Doing so requires a great deal of cellular energy expenditure. The resulting effect is fatigue after eating.
Why do you feel tired after eating?
Because you ate too many carbohydrates. This flooded your blood with excess glucose. That excess glucose has to go somewhere. The only place for it to go is into storage. You store excess glucose as body fat. Turning glucose into fat requires a ton of energy. This results in an energy deficit. The resulting effect is feeling tired after eating.
The solution to feeling tired after eating requires you to consume fewer carbohydrates at mealtime.
How many carbohydrates should you consume?
The answer to that question depends on the individual. If you’re looking for a general rule of thumb, try aiming for 30% of your total daily calories to come from unrefined carbohydrates. That means carbs like sweet potatoes, fruits, veggies, etc. This also means avoiding grains and processed foods like chips, pastas, etc.
A simple way to think about this is to divide your dinner plate into thirds. 1/3 of the plate should consist of meat. 1/3 should consist of vegetables. 1/3 should consist of healthy fats. Last night I ate the following:
- Pork roast (1/3 of my plate) – protein
- Sauerkraut (1/3 of my plate) – vegetable/carb
- Avocado (1/3 of my plate) – fat
When your dinner plate consists primarily of carbohydrates, you’re going to feel tired once you’re done! FYI, the average North American gets 70% of his/her total daily calories from carbohydrates. That’s more than two-thirds of a diner plate covered in carbs.
Want to know exactly how many carbs your body can tolerate?
Who’s at risk for feeling tired after eating?
Some of you will be able to binge on a Thanksgiving-like dinner and experience zero adverse effects. Others, will eat an apple and feel tired. Most of you will fall somewhere between these two extremes.
Elevated blood sugar levels put you at far greater risk of feeling tired after eating. I’m looking at the pre-diabetes and diabetes crowd here. Before you brush this off thinking that doesn’t apply to you, know that one-third of the population is suspected to have blood sugar abnormalities. There’s a good chance this applies to you!
When you’ve got blood sugar issues, your body struggles to take glucose from your blood and bring it into the cell. The effect is excess glucose hanging out in your bloodstream. All that excess glucose has to go somewhere.
Guess where it goes?
Yep, into body fat. Requiring a ton of energy to support that process.
If you feel tired after eating, it’s because the excess glucose contained in your high carbohydrate meal is now getting converted into body fat.
In order to stop feeling tired after meals, you need to alter both the quantity and type of carbohydrates you consume. Get your carbs from unrefined sources only. No more grains, pastas, cereals, candies, etc.
If that’s not enough, start slowly decreasing the number of carbohydrates you consume. Remember my rule of thirds – only one-third of your plate should contain carbs. The rest of your plate should be filled with healthy fats and proteins.
Let me know how it goes in the comments section below!