Attitude Change With Soylent?


I’ve never really had this problem until Soylent 1.4, but I’ve been feeling more aggressive on the day’s I drink Soylent exclusively. (I have one cheat day a week, and when I eat actual food it goes away.) FYI the 20 to 30 minutes after drinking Soylent I feel fine. Here is my video on it, I had a head ache during the recording sorry for the mellowness:

Have any of y’all experienced this?


Sounds similar to this person’s post.

This is hardly a scientific article but your comment on T levels and your symptoms reminded me of this blog. It’s a multipart series about testosterone and how to boost it naturally with diet and exercise.


If people keep on agression to ‘testosterone’ it will become a bad word in the media. As it is male shaming is increasing in the media. Aggression is not caused by testosterone alone, adrenalin also contributes to it, in my opinion.


Since the last 3-4 days i have been taking 25000 IU vit A pills once a day to reduce eyestrain (my food doesnt give me any), and i have noticed my mental aggression or probably ‘irritability’ too has come down a little. I am not sure if its because of those pills or something else but the timing is making me curious.

Maybe a balanced nutrition also keeps us ‘balanced’.


Maybe I’m weird but I’ve never felt this sort of connection between my food and my emotions. Other than, like, maybe I’ll want to eat a bunch of chocolate when I’m sad.

Eat too much and feel sick? Sure. Not eat enough and feel lightheaded? Absolutely. Feeling sad or aggressive after eating a particular food? Not that I can recall.


I agree


I often get aggro when I’m hungry. Maybe you need more calories?


This happens to me too. Usually it happens when I don’t feel like eating, but I can still tell my body needs food - I’ll have maybe a tiny breakfast and lunch out of a sense of obligation, and then slowly get more and more irritable until, filled with a powerful and venomous loathing for myself and everything around me, I finally eat a good meal or take a nap. I think in part it’s caused by my body getting tired of the taste/texture of Soylent, so I’ve started changing the flavoring and/or cooking more when this happens, to avoid getting burned out on it. I tried to force myself to stay on my first DIY recipe (which had a good, neutral taste and which I never flavored), and after a month or so of the aforementioned tiny obligation-meals I ended up getting so sick of it that I haven’t made it since. Unfortunately that meant switching to less-tasty recipes that I get sick of faster… flavor your Soylent, kids!


Yeay low blood sugar will make me very, very, very cranky… to the point of aggressiveness. Only has happened a few times in my life - usually when I was traveling or otherwise unable to access my normal foodstuffs and stay fed. A glass of orange juice would always do wonders to bring me back to normalcy in a hurry. Though of course I needed to follow it up with some food too. Thankfully I have no issues like that at all with Soylent.


Actually, @horsfield , it sounds opposite to that person’s post.

The “aggressive” person is fine for 20 to 30 minutes after drinking, but feels aggro on that day.
The “sad” person’s mood affect comes on in two minutes, and only lasts a short while - the rest of the day is fine.

My gut says that the aggressive person is primarily short on calories. The vast majority of people are bad estimators of their intake, and get more calories than they think. Soylent is the opposite - it’s really just 2000 calories a pouch. Several days of only 2000 calories will make many people irritable; it’s not an uncommon reaction when someone goes on a weight-loss diet.

My get says that the sad person is stimulating their vagus nerve in an unusual way with the Soylent. It might be from a stomach full of cold food, or maybe there’s something about Soylent that gives them that reaction…

Or maybe part of his brain was hoping it would be a a normal-food meal with different tastes (different parts of your brain can disagree with each other, so it’s possible that part of your brain may dislike Soylent.)


I got very aggy too the last couple of days, to the point where I sent everyone away and out of the house lol. I attributed it to lack of calories, as I was starving at the time. It was 6pm and I hadnt drank anything since 1 or 2.


I noticed an up-tick in energy to start/finish long-idle projects after starting to eat Soylent for just 7-10 meals a week. Your post increases my belief that there is a connection.

That may seem off topic, but I’ll suggest that the “aggression” you’re feeling may be simply your natural energy level, and that it is indeed connected with better balanced nutrition.

Most importantly YOU, by act of will, can decide if you are going to channel this extra energy into good works or ill-advised actions. What will you choose?


With great nutrition, comes great responsibility… :wink:


@horsfield and @MentalNomad, thanks for the thoughts. Yeah, I think my T-levels are cool, and no aggression or anything. The vagus nerve theory is interesting. I’m accustomed to chugging water and protein shakes, and neither of them have hit me like this. Soylent is thicker than any protein shake I’d make, so maybe it is exerting more acute pressure going down or once in the stomach. But I do also wonder about a reaction to one of the ingredients.

As I noted in the original thread here, drinking it more slowly seems to help.


I’m having the same experience. I’ve been on Soylent 1.4 almost exclusively for the past three days, and I notice after I have a meal, I feel very irritable and aggressive. My heartbeat also becomes rapid and I start feeling overwhelmed and on edge. It doesn’t last the entire day, but definitely a couple of hours after a Soylent meal. It’s very unpleasant. My boyfriend is having the same experience. We’ve been getting into spats because we both feel so irritable after drinking Soylent 1.4. I’ve never had any other version, by the way, and I’m pretty sure I have my meals calculated to a proportion that’s right or close to right for me. I’m going to start spacing out the meals into several snack size servings throughout the day to see if that helps.

Update: It’s been over a week now on almost exclusively Soylent. I don’t really notice the feeling anymore at all. I’ve been drinking more slowly. Maybe that’s it. It just seems gone now.

Soylent, IBS, the low-FODMAP diet, and gut bacteria

Okay, I have something that might verify what we’ve been experiencing. So I’m still noticing it. I thought it went away, but just 30 minutes after consuming a small amount of Soylent today, I became super jittery, anxious, and irritable and I have not calmed down since and it’s been about 4 hours. My heartbeat is crazy fast right now and it won’t stop.

Over the last two weeks, I’ve been noticing an incredibly unpleasant foggy headed feeling. I feel lightheaded and almost dizzyish, but not quite. I feel completely out of it mentally, like my brain doesn’t have enough energy, and I can’t seem to retain information well. It’s interfering with my ability to do things like drive. I almost never get into accidents and I’m a very cautious driver, but since being on Soylent, I’ve been making so many mistakes on the road and nearly getting into so many accidents that I don’t trust myself now to drive. My coordination is also completely off. I literally FEEL stupid somehow since being on Soylent.

I decided to look up whether people had experienced a similar foggy-headed, light-headed, inability to think, and I came across an interesting post where someone wrote about how they became pre-diabetic while on Soylent ( and one of the comments triggered me to look up hypoglycemia. Sure enough, all of my symptoms are there. I’m going to go to a doctor immediately.

Signs and Symptoms of Hypoglycemia (happen quickly):
Nervousness or anxiety
Sweating, chills and clamminess
Irritability or impatience
Confusion, including delirium
Rapid/fast heartbeat
Lightheadedness or dizziness
Hunger and nausea
Blurred/impaired vision
Tingling or numbness in the lips or tongue
Weakness or fatigue
Anger, stubbornness, or sadness
Lack of coordination
Nightmares or crying out during sleep

More at:


What version did these symptoms happen with?


Soylent 1.4. I suspect it has something to do with the isomaltulose. I have a very fast metabolism and I’m autistic. I’ve had a number of MRIs done that study people with autism that indicate I’m what they call a “high activator”. Supposedly, an input goes in and my entire brain has a tendency to light up and look like a fireball on their reports. Maybe the isomaltulose is too slow-burning for my energy needs. Maybe my body isn’t processing it and I’m not absorbing it. That would fit with my IBS since people with IBS tend to have an inability to process certain carbohydrates, and I may be one of those people who can’t process fructose or sucrose very well (which my GI doctor says I need to be tested for), and isomaltulose is reportedly incompatible with people with a fructose or sucrose intolerance. I’m having other symptoms as well that might indicate a potential carbohydrate malabsorption issue (signs of foul smelling stool). So, all of this fits rather well for me and I’m going to go to the doctor with this information at my next appointment. In the meantime, I’m going to lay off the Soylent. These episodes of hypoglycemia, if that’s what it is, feel very scary.

My boyfriend is having the exact same issues (attitude, anger, irritability, overwhelm, rapid heart beat, foul smelling stool, foggy headedness, inability to think) but not as severe since he is supplementing more of his diet with traditional food and eating things like cake and bread at work. Coincidentally, both of us seem to be craving lots of bready foods like pizza, cereal, and doughnuts even though we’re not hungry. Our symptoms reduce when we have these foods. Yesterday, after I had that episode, I had some ramen and my symptoms went down quickly.


Not to be snarky, but it is amazing how frequently a person and their “partner” taste Soylent as having the same quality, while at the same time we can read here that people have wildly different reactions to the stuff.

It is almost as if there is a powerful incentive for people living together to taste something the same way, because it’s an important ingredient in the harmony of a relationship. I think that a researcher going through comments here would notice the frequency of comments like “and my partner feels the same way”.

I can think of several possible explanations for this phenomenon and I’m not sure why it seems to happen. Maybe Soylent is more sensitive to exactly how it is prepared than I realize, so people living together are reflecting that the Soylent they tried was prepared in exactly the same way.


Utensils can also affect the perceived taste of food.

So a non-obvious contributing factor could be that partners tend to drink Soylent out of the same vessels.