Why Does the Keto Diet Make Me Sick?
Before I start this post, I want to make 3 things clear:
- I understand that when you first start doing keto, it’s common to experience what’s called the “keto flu.” I definitely had that. But I never, ever, got out of that phase.
- I am not against the keto diet. Many people have benefited from it. Please don’t think I’m one of those people trying to label keto as harmful or evil. It’s not.
- In fact, it can be incredibly helpful for some, including people with conditions like Chronic Fatigue Syndrome (CFS), Fibromyalgia, or POTS. I’ve even seen that some organizations that support people with CFS recommend keto with good results. Everyone’s body is different.
That said, if you have a dysregulated nervous system, I’d suggest taking your time with any dietary change., not just keto.
2019
The keto diet is a high-fat, low-carbohydrate diet designed to put the body into a state of ketosis, where it burns fat for fuel instead of carbs. While transitioning, your body undergoes significant changes, and this can activate your sympathetic nervous system (fight or flight system). That’s what people refer to as the “keto flu.”
In 2019, I decided to try the keto diet. I wouldn’t have considered myself “chronically ill” at the time, although I was starting to notice some things in my body that felt off. I was still generally functional. Emotionally, I was also healing from a very broken heart, and like many, I wanted to feel better, get fit, and regain a sense of control. Several of my friends were doing keto and having great results, so I figured, why not?
I did my research, and I bought what I needed. I honestly felt rather prepared. Friends warned me about the keto flu and gave lots of suggestions. Things like pickle juice, electrolyte powders, etc. to help manage it. So, I felt ready.
Keto Flu for 2 Months
I got the keto flu, but I never got past it. It was strange. I’ve tried other diets before, and my body usually adjusts within a few days or a week. But this was different. I kept waiting for the surge of energy everyone talked about. My friends kept telling me that their workouts felt amazing and your brain lights up. That never happened for me.
Every workout left me feeling quite wrecked. I felt heavy and foggy. I was also dealing with constipation, which was new for me.
After two months of pushing through, what finally made me stop was the burning and prickling in my legs and feet. It felt like nerve pain, almost like neuropathy. Looking back, I still can’t believe I forced my body to keep going for that long.
I now realize I have a really bad habit of comparing myself to others. If my friends were okay on keto, I thought I should be too. If research said keto was great, I believed it had to work for me. I wasn’t listening to the obvious signs my body was sending: this diet was not for me.
At that time, I wasn’t yet dealing with the more severe aspects of my health issues. But looking back, I can see that my system was already fragile, and I pushed it too hard. Maybe I did start off gradually enough? It’s hard to say. The worst part of all is that I really didn’t lose that much weight.
2020: 1 Year Later…
Then came 2020.
When my health crashed that year, the sensations I felt reminded me of how I’d felt on keto. But this time, I wasn’t doing any kind of diet. I was just getting very, very sick.
A month in, I went to the emergency room because I didn’t know what else to do. My symptoms were coming in fast. I had intense pressure in my head, shaking, labored breathing. It was very overwhelming. I truly believed that something was very wrong.
It was early in the COVID pandemic. Such horrible timing. The ER staff made it clear they felt I was wasting their time. That hurt, especially since I was alone and scared. But I get it. Healthcare workers were under intense pressure. I was discharged with no answers and hit with a $6,000 hospital bill (with insurance). I only spoke to a doctor for less than two minutes. He kept insisting that I must be pregnant. Such a horrible experience.
Anyone with chronic illness has likely experienced something similar, dismissive responses, eye rolls, and the simple explain-away of “you’re just depressed”. Since then, I’ve mostly stopped seeking help from traditional medicine. I’m not against it, medicine saves lives, but it just hasn’t helped me with these issues.
Lesson Learned
Looking back, I now see that entering ketosis interacted with my nervous system in a way that amplified my underlying dysregulation. It didn’t cause my condition, but it exposed it. These were the early signs. As much as it “didn’t work” it was trying to tell me something.
Keto seemed to increase sympathetic nervous system activity which was pushing my body into a sustained fight-or-flight state. It destabilized me further. The diet revealed vulnerabilities that were already there, simmering beneath the surface.
It’s also worth noting something I’ve observed in myself: when I start anything new, whether a protocol, supplement, or even a basic vitamin, my system tends to react with disproportionate intensity. I’ve come to understand this as a pattern linked to chronic freeze response. There’s often an exaggerated initial reaction, followed by a quick plateau, and eventually a full drop-off in responsiveness. It’s as if the system burns through its capacity early, then shuts down under overstimulation. The only weird thing about the Keto diet was there was never an official drop off period. It was purely initial reaction oriented.
We are all different. What didn’t work for me may work great for someone else. But based on my experience, I wouldn’t recommend keto to anyone dealing with nervous system dysregulation, CFS, or similar conditions unless they move very slowly and cautiously. I’d also recommend doing this under the watch of a health professional.
Pacing is everything. That’s something I’ve learned the hard way. Whether it’s food, exercise, or even breathwork, your body will let you know if it’s too much. I’ve even had difficult reactions to certain breathing techniques. When your system is overloaded, everything feels like a trigger.
Resources & Community
There’s a great Reddit thread that discusses similar experiences from others with CFS who didn’t respond well to keto. Some had positive experiences too, which again shows how individual all of this is. But if you’re looking for cautionary tales or relatable stories, this is worth checking out:
👉 Another cautionary tale: my negative Keto diet experiment as someone with CFS – Reddit
Energy Work Sensitivity in a Dysregulated World – Astra speaks
