13 Reasons You Feel Tired After Eating + Solutions to Fatigue
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Why do you get tired after meals? Read on to learn more about post-meal fatigue and how you can help combat that middle-of-the-day tired spell or the crushing post-dinner feeling of tiredness.
Fatigue Is (Mainly) from the Hypothalamus
All of the most important reasons for fatigue have to do with the hypothalamus, which is something I discuss quite a bit.
Several hypothalamic areas, such as the suprachiasmatic nucleus (SCN), lateral hypothalamus (LH), and ventromedial hypothalamic nucleus (VMH) are implicated in the regulation of sleep, wakefulness, and food intake .
NOTE: In the scientific literature, post-meal fatigue is known as “post-prandial fatigue.”
Post-Meal Fatigue Is a Metabolic Problem
Metabolism is the process where the energy goes in (caloric intake) and that energy is utilized by the body.
When energy isn’t utilized the way it’s supposed to, you have a metabolic problem.
For example, if you’re obese, the calories you take in are not being expended by having more physical and mental energy. Instead, it’s being stored as fat. That’s a metabolic problem.
Another metabolic problem is when you expend more calories than you take in and you get too thin. These calories might not be digested – they may be used for your immune system to create inflammation, or you might have increased body temperature.
Being too thin or too overweight are both metabolic problems, just of a slightly different nature.
When you take calories in, they are supposed to be used by your cells and make you feel more energetic, think more clearly, and have a better mood.
13 Reasons You Get Tired After Meals
1) Carbs and Glucose (by Suppressing Orexin)
I’ve written about orexin extensively and I’ve also written a post on fatigue after meals (has all the references).
It’s well known that too much glucose in the blood suppresses orexin, which is the most significant peptide that controls wakefulness. It’s most active in the hypothalamus.
Any carb will end up breaking down into glucose, so if you eat too many carbohydrates, you feel tired after a meal.
When I eat too many carbs or too much glucose, I get tired. This used to be the case much more than it is now.
The reason why glucose used to affect me has more to do with changes in the hypothalamus. I’ve noticed that lectins (by causing inflammation) make me more sensitive to glucose-induced fatigue. Since I restrict dietary lectins and other plant immunostimulants, this problem minimized.
In general, carbohydrates and plant-based foods contain a diverse range of chemicals that are capable of spiking your immune system (i.e., causing inflammation), if you’re susceptible.
2) Inflammation (by Suppressing Orexin)
Inflammatory cytokines like TNF and IL-1b can suppress orexin.
Many people have undiscovered food sensitivities and get inflammation from some component of their meals.
This was the most significant cause of fatigue after meals for me, and when I took out all of the foods that caused me inflammation, the post-meal fatigue went away.
If you are struggling with post-meal fatigue, you may want to try out the Lectin Avoidance Diet to figure out the food items that cause your fatigue due to inflammation.
3) Acidity, Orexin, and Post-Meal Fatigue
Orexin is extremely sensitive to the minor changes of pH in the blood.
When blood acidity temporarily goes down and your blood becomes slightly more alkaline, orexin is more likely to be suppressed and tiredness will ensue.
When you chew, your stomach needs to create hydrochloric acid (HCL), which is very acidic. This pulls some acidity out of your blood and temporarily causes a small increase in pH (lower acidity).
4) ATP and Orexin
Orexin is suppressed by glucose, as mentioned. But, when we have enough filled energy-related molecules including adenosine triphosphate (ATP) and pyruvate, orexin isn’t as easily suppressed .
Indeed, researchers have found that in CFS, people have less pyruvate in their cells.
Mitochondria are what control the production of energy-related molecules.
This means that if your mitochondria aren’t working well and you’re not producing adequate ATP, a meal with carbs is more likely to make you tired.
Digestion is an energy-intense process and I wouldn’t be surprised if it used a lot of ATP. Also, if you are getting inflammation from the food, that will deplete your energy reserves even more.
5) Leptin and Post-Meal Fatigue
When you eat, leptin goes up.
Leptin is capable of spiking inflammation and making you tired. Leptin spikes are associated with fatigue in studies.
Interestingly, leptin increases more from carbohydrates than protein or fat, which may explain, in part, why carbs make people more tired than other macronutrients.
When you have an inflammatory environment, leptin is capable of causing much more inflammation, which is why fatigue only occurs from leptin if you already have inflammation.
Indeed, this is one reason why carbs make people feel more tired.
6) Low NAD+/SIRT1 and Post-Meal Fatigue
NAD+ is important for DNA repair, stress resistance, and cell death [3, 4].
NAD+ also increases metabolism and acts as a signal for energy balance. When your mitochondria are working well, you produce more NAD+, and this sets in motion a bunch of signals to increase energy intake and expenditure.
NAD+ makes you more insulin and leptin sensitive. When you have low levels, your general energy declines, your mitochondria works poorly, you have higher blood sugar, and this increases the risk of post-meal fatigue.
7) Less Blood Flow to the Brain
When you eat, the blood vessels of the GI tract dilate, increasing local blood flow. Blood rushes to your stomach to start processing the food.
Since the blood is moving to your GI system, this means your brain has less blood and therefore less oxygen and nutrients. This can contribute to fatigue.
8) Parasympathetic Activation (Rest and Digest)
When you eat, your parasympathetic system (rest and digest) increases, and the sympathetic system (fight or flight) decreases. This happens regardless of the composition of the meal.
Think about how you feel relaxed after a bowel movement. That’s parasympathetic activation.
I experience this a bit after a meal, but it’s more of a relaxation than a fatigue – and to the extent that I do feel tired, it’s very mild and dissipates quickly.
Regardless, parasympathetic activation can contribute to post-meal fatigue.
9) Circadian Rhythms and Fatigue
You might notice that you feel more tired after lunch than breakfast or dinner.
This is because there’s a rhythm to wakefulness and at around 1 to 3 PM, you naturally feel more tired. This is called the afternoon dip.
After 10 AM, sleep urge starts to go up, peaking around 2 PM. The wavy orange/red line shows the circadian rhythm of fatigue. The other part (sleep need) illustrates the steady buildup of metabolic products such as adenosine that cause fatigue.
The bottom line is that you are more likely to get tired after lunch for circadian reasons.
10) CCK and Post-Meal Fatigue
Cholecystokinin (CCK) is a significant factor in post-meal fatigue.
CCK is a gut hormone that’s mainly released in response to a fat-rich or lectin-rich meal. Long chain fats (saturated, MUFAs, PUFAs) are especially potent CCK inducers .
A high protein diet also increases CCK.
Studies will often use the fat from olive oil to induce CCK to release (oleate), which I’ve noticed pretty potently releases CCK for me .
CCK is responsible for:
- Causing sleepiness/fatigue because it directly interacts with the hypothalamus (despite the fact that it activates orexin 
- Inhibiting hypothalamic noradrenaline, which is a plausible mechanism for CCK’s fatigue-inducing and appetite-suppressing effect 
- Stimulating wakefulness and fatigue in the hypothalamus
Giving a CCK blocker to rats prevented post-meal fatigue, whereas in humans it actually increased post-meal fatigue .
It’s accepted that CCK has sleep-promoting and wake-promoting properties, but the balance depends on other factors, in my opinion. If your hypothalamus is working well, it may be more wakeful promoting and if not, it can be more sleep-promoting.
- Directly interacts with the hypothalamus to stimulate the flow of your colon, which will cause gas 
- Follows a circadian rhythm and is likely released more in the daytime when our system is primed to eat
- Increases bloating
- Decreases stomach acid
- Causes gut pain hypersensitivity 
- Causes nausea, anxiety, and satiation
People with IBS are more likely to release too much CCK (a gut hormone) in response to a fat-rich meal.
In rats, legume lectins (and probably others) cause increased secretion of CCK. .
CCK receptors are made of sugars that are the target of lectins, such as wheat germ agglutinin .
11) Insulin, BCAAs, and Tryptophan
When you eat, your insulin goes up. Insulin stimulates the uptake of valine, leucine, and isoleucine into muscle, but not tryptophan.
The theory is that this lowers the ratio of these BCAAs in the bloodstream relative to tryptophan.
Uptake of tryptophan by the brain thus increases. In the brain, tryptophan is converted to serotonin, which is then converted to melatonin. Increased brain serotonin and melatonin levels result in sleepiness.
This might be why eating a higher protein meal can blunt the fatigue a bit.
However, I do believe that this may be more significant for some people. For example, in people with CFS, serotonin increases more in response to a tryptophan load .
When I take things that increase serotonin (such as 5-HTP), I do get tired, so it makes sense that this explanation is more pronounced if you’ve got the genetic predisposition.
12) Insulin-Induced Low Potassium
Insulin causes serum potassium outside of the cells to go inside.
This can lead to a lower potassium state. The effects of low potassium include fatigue, muscle weakness, or paralysis.
However, when I supplement with potassium, it has a very small effect. This is certainly not very significant for me.
13) Cannabinoids and Orexin
Cannabis is more often associated with making you sleepier, but in actuality, low levels of cannabinoids potentiate orexin and can stimulate wakefulness.
I’ve noticed that post-meal fatigue is more common when people have variations in their cannabinoid receptors. That could have to do with cannabinoids activating orexin, or it could have to do with people with these variations being more sensitive to foods and therefore they have more inflammation from their diet.
Top Ways to Prevent Post-Meal Fatigue
Some of the most significant changes that have helped get rid of my post-meal fatigue were reducing plant-based foods in my diet (grains, beans, nuts, and seeds), consuming fewer carbs, and increasing my protein intake. See the lectin avoidance diet.
With SelfDecode, people can get a closer look at their genetics, which can help home in on the root cause of their fatigue.
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Here are some of the best methods to help post-meal fatigue. These recommendations are a product of an insane amount of research and experimentation.
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Joe Cohen won the genetic lottery of bad genes. As a kid, he suffered from inflammation, brain fog, fatigue, digestive problems, anxiety, depression, and other issues that were poorly understood in both conventional and alternative medicine.
I had many of the same fatigue issues after eating almost every meal. I tried eliminating so many things and tried so many different diets only to find that I would still feel this immense fatigue and brain fog after eating.
In the end I made a connection to coffee. Coffee was the culprit, and fit the bill in every aspect for the drug like fatigue I was experiencing. I had gotten used to drinking too much (just for social reasons) and wasn’t maintaining the same intake day to day. because I never “needed” coffee I would only drink it in the mornings on my days off, every other day it was a challenge to get enough to get me up to the amount of caffeine I had built a tolerance to, unbeknownst to me.
I tried quitting cold turkey and only had headaches for a few days but felt low mood and very low motivation for the following four months. When I realized coffe was the culprit I started drinking a cup a day with a plan to wean off of the caffeine, boy that first cup in months was amazing.
I stopped drinking or consuming any type of caffeine regularly about a week ago. I feel great, I don’t get tired when I eat and I finally feel rested after a full nights sleep.
All of this has to do with adenosine and it’s interactions with caffeine in the brain and body. I believe high carb meals are also intertwined with adesonine and caffeine somehow.
It may sound far fetched but if you read about other’s experiences with caffeine withdrawal symptoms and how long they last you’ll understand how serious the issue is. It also doesn’t help that it gets overlooked because it’s so socially accepted and widely consumed, not to mention that DD and Starbucks are huge money makers…
Check thyroid function. If OK check lyme disease. Get yourself checked by Igenix lab. Not the crappy ELISA.
I started hacking my health about ten years ago with a search for answers to my myriad of health disorders. It took me about a year to come up with a diagnosis. Andersen Tawil syndrome. It is a type of Primary Periodic Paralysis. The small fluctuations of potassium many can handle literally send me and family members into what some describe as food coma. Carbohydrate avoidance health lesson I learned after my diagnosis. Insulin surge causes potassium drop in serum and I become tired and paralyze. Even when my serum levels are in the normal range. To top it all off I learned I have a pathological allele for adenosine monophosphate deaminase deficiency. Bugger me, I learned that this specific enzyme deficiency is thought to worsen a metabolic myopathy, which my disorder is. It may be why I am so tired and have constant burning muscles. I am considering a run with ribose to help with my energy shortage according to info I have read it can help with the overload of ATP in my cells. My Andersen Tawil syndrome presentation has been considered atypical because of these very symptoms.
have you tried iodine, I suppose?
I had the same problem. Turned out to be celiac disease. Doctors can be jerks when it comes to weight.
Braggs apple cider vinegar with honey, mixed with flavored soda water or juice! its good! just a tablespoon of acv at a time!
Maybe you should try keto. Or Atkins (same idea). I find that I do better with low-carb eating, not just for weight loss, but for energy. Your body learns to burn fat as energy instead of glucose. It may be worth a try… I’d go to Atkin’s first, try the induction for a few weeks and then modify a little for more veggies, but you really have to let go of stuff we were taught about eating. Read up on ketogenics and also Grain Brain… maybe you need to seriously modify the way you eat for good. Good luck.
Just found article. Been to 9 doctors. No one can explain why such major weight increase. Went from 136lbs to now nearly 300 lbs. All I get from doctors is exercise, exercise and eat healthy. I use to be a running, so believe me I know how to exercise. I’m 5’4, and weighing nearly 300 lbs makes it very hard. Going to the doctor I always get a clean bill of health. I explain to them how exhausted I get from eating. Fruits knocks me out. Nuts do the same things. Smoothies kill my energy. Protein bars do the same. And yes most regular foods kills my energy! I have brain fog, exhausting, and weight issues no one knows the answer too. All I do is sleep! I feel my life is wasting away. I’m no good for anything most of the time. Coffee helps me stay awake, but coffee was the one thing I added to my diet when the change in weight started coming on. Spanish also give me energy however I have to eat it plain, if eat it with a salad it does me no good, I still get tired. I have no answer. I’ve done some of everything and I’m still overweight, exhausted and just lost. Only thing that helps is to not eat!
well i don’t get tired, i get very relaxed and snoozy. i, sometimes, nap and perk right up. this happens to all foods i digest.
then again i’m on tons of antihypertensives.
but the conflicts i get from the professionals are… typical.
well, that solved nothing. 😛
HCLF plant-based meals don’t make me tired. Meat and sat-fat does. MUFA / PUFA oils / nuts and seeds can, depending on the dose.
I’ve been trying to incorporate apple cider vinegar into my diet. Any suggestion about how I can make this palatable? How much and how often should I use it?
Mixed with honey and / or as salad dressing
I don’t like vinegary anything so this has been a real challenge for me. But I hit upon a solution when I added a squeeze of fresh lemon to the vinegar and honey mix I do one tablespoon of each, start with warm water not hot! So the honey will mix I do about a 1/4 C water and then add an ice cube to cool it back down! Do to your taste. It almost taste good!
Natural sugars, such as those found in fruit, can also produce an energy crash. If you find that you’re sleepy after eating fruit in the morning, instead try eating it in the afternoon and mixing with nuts to help your body process the sugar. A little planning in your food choices will go a long way in preventing you from feeling always tired after eating.
is the Hi-Maize ok for lectin sensitivity ? corn is normally high in lectins
This isn’t related to the topic at hand, but knowing that you take pure caprylic oil if you don’t want to line Mr. Ass-spray’s pockets and want a source of pure caprylic oil, try this new brand called Mickey T. It’s being sold on Amazon now and its cheaper than the alternative.
I’ve got no problem lining Asprey’s pocket if he’s providing a good or service. His podcast, blog and collection of ideas are a type of service, although all have gotten shitty in time. And his dogmatic approach can be more of a disservice to many people, such as myself, even if it helps others.
Anyway, since the product is 5$ cheaper, I’m all for it.
I have no problem with fat. I know that many people say you get tired from fat but for me fat is probably the macronutrient that works best. Regarding sugar and protein it depends how big the meal is… I started eating small meals every few hours in order to keep my blood sugar on up stuff… it works quite well.
I usually have carbs after workout. I do BBD and HIIT once a week each and depending on the amount and the type of carbs I feel either great, like on drugs, fine/normal and or I get tired (from eating too much carbs in one meal)…
I assume taking hydrocortisone after a meal is just for the sake of experimentation. Would it actually be practical to raise your cortisol every time before a meal? Or should lowering CRH be the target
just for experimentation..lowering CRH
hi again Joseph, & thx for another good post.
re. other theories number ‘5) Insulin, large neutral amino acids, and tryptophan’.
…now i do not know if this theory is correct or not, tho it does sound plausible.
but your comment of “This theory doesn’t pan out for me because I’ve taken BCAAs with no noticeable affect. Perhaps it has an effect, but it’s too small to be noticed compared to the other reasons.”
Does not test the theory…well i guess it tests the ‘opposite’ of the theory…ie. taking BCAA’s could keep you awake.
The idea of this particular theory is to reduce all LNAA’s in the blood stream, except for Tryptophan, the last thing you want to be doing is downing BCAA’s.
Some people suggest a potato before bed (with no protein) to help get the tryptophan across the BBB. I suppose this is to ‘draw out’ the competing LNAA’s from the blood and in to muscle.
The theory is that the ratio of BCAAs to tryptophan decreases and that’s the problem because tryptophan will be more likely to cross the brain barrier.
If you take BCAAs then that should rebalance the ratio and you shouldn’t feel fatigued because tryptophan isn’t preferentially crossing the brain barrier.
How does this not test the theory?
totally agree. I misinterpreted your expected outcome of your bcaa self test.
(I initially thought you were inferring that taking bcaa’s should make you more tired according to the theory)
I have struggled with post-prandial fatigue for as long as I can remember. I was diagnosed with CFS in 1996 by Dr. Paul Cheney. I have recently realized that most of this stems from Salicylate Intolerance and Histamine Intolerance. I get very fatigued from fats high in salicylates: olive oil, coconut oil, avocados. Animal fats like butter, tallow, and lard do not affect me this way. Likewise, meat that has been aged makes me incredibly tired, but unaged meat does not.
I appreciate all the great information you share.
That would fall under the inflammation category and maybe CRH
When you eat a fat-rich meal, it introduce fat into the bloodstream. This causes the red blood cells to agglutinate, that is, to clump together. This prevents some of them from entering the capillaries, resulting in up to a 20% loss in oxygen available to the tissue. Of course, this can bring on fatigue. I understand that eating a high sugar meal causes a spike in blood sugar, followed by a greater than normal dip in it. The body interprets this as a starvation condition and dumps emergency fatty acids into the blood, resulting in the same mechanism as above to bring about fatigue.
I don’t agree with that 100%. Unsaturated fats, especially polyunsaturated fats, seem to thin the blood. Saturated fats may thicken the blood a bit. Blood agglutination may cause immune reactive shocks like if someone is bitten by a venomous snake (because that’s what sneak venoms do), which is much worse than fatigue.
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