Why Does Soylent Make Me Tired?

I get heavy fatigue right after drinking Soylent and I want to figure out why…

My Soylent arrived 10 days ago. I started drinking it for about one meal a day, ~ 1/3 of my caloric intake. At first the effect was subtle but within 5 days I was fatigued (particularly right after drinking Soylent), had a sore throat, and felt like I was coming down with something.

I gave Soylent a break for a few days. When I resumed it Friday night I drank about 700 calories worth for dinner and immediately felt highly lethargic, slept an unusually high amount that night, and felt mildly fatigued throughout the next day.

One thing to note is that instead of the usual oil blend I add 2 tablespoons of MCT oil to one serving of Soylent. I tolerate such quantities of MCT just fine in general so unless it’s having some strange impact in combo with the Soylent, I doubt that’s the culprit.

Some info on me:

Age: 27
Weight; 160
BMI: 21.1
Total HDL ratio: 3.3
Triglycerides to HDL: 2.1
HDL: 52
LDL: 97
Triglycerides: 108
Total Cholesterol: 171
Non-HDL Cholesterol: 119
Apo B: 80
Lp(a): <10
Insulin: 2
Hemoglobin A1c: 5.1
Glucose: 83

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I experienced something similar. I know my experience is anecdotal, but my tiredness goes away when I add an extra table spoon of olive oil to my mix. I did this after taking a look at the fat/carb/protein content in the food i normally consumed and tried to emulate it.

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Interesting hakabat, thanks for chiming in. My blend actually has a higher than usual fat ratio since I add 2 whole tablespoons of MCT oil to each serving (meal) of Soylent. I can try adjusting the oil ratio though.

For what its worth, I don’t know if I felt more tired after starting Soylent vs before, but I have experienced a significant boost in energy upon adding more oil (official blend). So its plausible that it might help, as @hakabat suggested.

I would either cut out the extra oil, or eat more Soylent to go with it. Your body is obviously having a hard time processing all the oils. You don’t get sleepy at Thanksgiving or big meals because you want to. :stuck_out_tongue: Our bodys shut down and sleep so we don’t overexert ourselves while they’re doing the heavy digestion.

I had a family member who had to avoid food with high fat because he couldn’t break down them down. His reaction after eating any high fat foods, was just like you…he’d fall asleep after eating and sleep all night. I guess it’s a genetic disorder that runs down that side of my family. Might be worth mentioning to your local dr to see what they think as well.

In my experience grain/starches are more difficult to digest than fat, and starches are more likely to lead to the post-meal crash… YMMV…

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Ya for a normal person it is, and that’s why we become lethargic after eating too much of the stuffing and breads and stuff at big meals. That’s why fats are great for quick energy, they digest so easily. Unless maybe he was on a low carb diet before (or still is), then it would lean towards the oil and trouble digesting it. It’s tough to know without seeing a doctor and doing tests though. :stuck_out_tongue:

He can self test by cutting out 2 meals for Soylent, no oil Soylent, etc. I enjoy the testing part haha…

I got the theory that lack of enough enzyme to break down the oats is one of culprits to these symptoms some people describe. The body uses quite a bit of energy just breaking down food normally (at least that is what I have heard my entire life) and since it has been mentioned before by the Soylent team that it seems lack of enough enzime/time to break down these oats is one of the reasons for the gas for an example… I theorize that people are getting tired because the body is working hard at making more enzymes for breaking down the oats or working hard in general with digesting it.

From reading other people’s experiences with Soylent 1.0, I’ve become quite certain that the gas and tiredness are caused by a food combination issue. Probably the rice protein and the oat flour, and/or the rice protein and the maltodextrin.

And this may be linked to an enzyme issue. Some people may have enough digestive enzymes to mitigate the gas, or produce the enzymes easily enough so as not to cause fatigue, while other people don’t.

This could also explain why some people do OK on their DIY formula, but do poorly on Soylent 1.0; their DIY is using different protein and/or starches that don’t cause a food combination issue, hence no gas and fatigue on DIY.

If someone who likes conducting research @axcho is so inclined to try various combinations of starches and proteins together I’d be fascinated to hear the results.


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I’m 37 and in decent shape and started with 2 of my 3 m3als being soylent for a week. I had exactly the same effects. The first 2 days I felt fine, super full every time I drank it, but overall, my energy levels were normal. By the 3rd day, I felt super fatigued and this just continued getting worse. Around the 7th day, my chest started feeling tight like it was harder to breath, or I was exhausted. I stopped soylent and started full foods and water immediately. I felt much better, but also realized because Soylent made me so full feeling on a liquid level, I had heavily cut back on my water intake and hadn’t noticed. I am going to try another week and make sure I have enough water this time to test the effects, but I believe the fatigue and tightness in my chest was due to dehydration.


You’ve actually got that backwards… carbs are quick and easy to digest.

If you have a meal with a lot of simple carbs, however, without much fat/protein/fiber, then the sugars will get into your bloodstream very quickly (can cause a “sugar high”), and then when the sugar is gone, you will “crash.” Basically, your body got momentarily used to having a lot of sugar, and when it ran out (because it’s digested so quickly), the body needs time to adjust again.

If you have more complex carbs instead of simple carbs, and fiber mixed with some protein and fat, this doesn’t happen, because the other stuff - especially the fat - slows down the absorption.

Sugar is more easily digested and more easily used for energy than fat. That’s exactly why if you eat a lot of fat and sugar, the body burns the sugar… and, not needing the fat for fuel, just stores it away in your fat cells. It’s easier than burning it.

The only way to stop the body from preferring sugar over fat is to give it something even easier to burn for energy, like alcohol.


That does sound very much like dehydration. I have to be careful to keep up my water levels when I’m fasting, or else I feel exactly that way.

When I was first learning to fast, I used to think that was tiredness from having no food - I only later learned that it was mostly dehydration.

Now I’m wondering how many people are tired because they don’t realize they’re not getting enough fluids? It’s definitely easy to forget, when your meals consist of drinking…


I had recently started make your own 2.0 powder. I was extremely tired and fell asleep several times shortly after drinking it. About 45 minutes after. That has never happened to me before with any other food. I tried it several times over the next week to make sure and it happened again and again. I don’t have any food allergies I ever encountered in my life. I could eat a box of cookies, a tub of ice cream and a two liter of soda without a crash. Something else is doing this in Soylent.

Its because its liquid food. Try sipping it over a couple hours and see if you feel different. In a 100% Soylent (or similar product) day at 2000cal, I would sip all day long, refilling every 500cal.

In other words: it’s an extreme case of the itis.

I had the same problem. I did not know why I felt very tired after soylent. I tried to drink it a few times, and every time was the same.

Only after one year later I found out, that I have Celiac disease, and I’m very gluten intolerant. Soylent is made from oat, and it has a lot of avenins (which is not considered to be gluten by some of the doctors, even though it’s in the same family of glutens). It’s definitely allergic for people that are gluten intollerant.

Are you drinking sufficient water in addition to Soylent? I had this issue until I simply drank water right after having Soylent. My hypothesis is simply your body doesn’t have enough water to properly hydrolyze the nutrients (or at least not fast enough and efficiently) so you feel tired so you will slow down so your body can work on the Soylent you just consumed.

I generally find increasing water intake solves a lot of issues for me.

Sounds.like it could be a digestion enzyme issue…i know when i tried the bulletproof cooking (high protein/fat, low carb) i had similar effects…until i introduced digestive enzymes…you can find them over the counter at most pharmacy…i personally used spring valley from walmart. Taken 1 tablet about 20 mins before my Soylent