What really causes keto flu, and how can you prevent it?

As the ketogenic diets grow in popularity, a new review sheds light on the short-term side effects of keto induction and offers science-supported solutions to help manage the dreaded “keto-flu”.

Symptoms during the start of a ketogenic diet: a scoping evaluation of performances, mechanisms and auxiliary strategies. Image Credit: Eldar Nurkovic / Shutterstock

Published in a recent study in the magazine Frontiers in NutritionResearchers from the University of Bergen, Norway, evaluated symptoms during the transition to a ketogenic diet (KD), ie keto induction.

KD is characterized by a higher intake of fats, moderate intake of proteins and a lower consumption of carbohydrates. The low nutritional hydrate maintains the dominant oxidation of fatty acids, so that the starvation is simulated that includes ketogenesis in the liver. Ketogenesis includes the synthesis of keton bodies, such as acetone, β-hydroxybutyraat and acetoacetate, which serve as an alternative branch for cells.

KDs have been extensively investigated as therapeutic options for cancer, obesity, diabetes, dementia and cardiovascular disease. For more than a century, these diets have been used to treat stubborn epilepsy in adults and children. Research also shows the neuroprotective effects of KD, with implications for Parkinson’s disease, Alzheimer’s disease, glioma and migraine, among other things.

However, a potential obstacle for the adoption of KD is the experience of unfavorable symptoms, called Keto-Flu in the first weeks. These symptoms are fatigue, brain fog, lethargy, light in the head, headache, mood changes, halitosis, muscle cramps, reduced training capacity, diarrhea and constipation. These arise as a result of physiological shifts such as electrolyte loss (eg sodium and potassium), reduced glucose availability during metabolic adjustment and temporary changes in the composition of the intestinal microbiota. Documenting these symptoms during keto induction and understanding the underlying mechanisms can help prevent or treat these symptoms.

The study and findings

In the current study, researchers have assessed the literature on Keto-Flu with regard to the underlying physiological symptoms and evidence for symptom lighting and treatment. First they searched the web of science, medline and embase databases for relevant studies. The eligible studies were those in which one of the study groups followed a KD and those who investigated the side effects, mechanisms and interventions for the relief of symptoms of keto induction.

Non-English studies, animal studies, studies that investigate only benefits in the long term and side effects of KD and that with fat-rich diets, not few carbohydrates, were excluded. In general, the researchers identified more than 5,700 records from searches on database. After deduplication and title/abstract screening, 115 articles were assessed on suitability, 89 of which were included in the study.

These studies described keto induction as a series of passing symptoms. These symptoms occur within two to three days after the initiation of KD and dissolve within two to four weeks, with minimal or no intervention, driven by mechanisms such as natriuresis (excessive sodium excretion), hypovolemy (low blood volume), reduced energy sub -street availability and changes in the metaboles. Rarely were the symptoms serious enough to justify KD staging. Symptoms included muscle cramps, fatigue, mood changes, light in the head, constipation, halitosis and diarrhea.

Macronutrient relationships used in some standard diet formulations [calculated by mass, not energy percentage of total energy].

Some studies reported other symptoms, including hypoglycaemia, kidney stones, acidosis, prurigo pigmentosa (a rare skin rash linked to ketosis), emesis and nausea. In some studies, halitosis was reported as a common side effect of keto induction. It was reported that it performed 38% of the time in people on KD compared to 8% for people with a low -fat diet. Gastrointestinal side effects were one of the most common keto induction symptoms.

Constipation would occur 15% to 63% of the time in pediatric populations, while it was described as a common side effect in healthy adult populations. Vomiting and nausea were also reported as common side effects in children. Furthermore, dizziness and dizziness were common symptoms in adults, but not in children. Hypoglycaemia was reported that it mainly influenced the pediatric population, without direct reports of adults occurring, although symptoms such as fatigue and dizziness in adults can reflect mild glucose fluctuations.

The occurrence of kidney stones was 2.5% to 4% and ≤25% in studies of long -term compliance with KD. Short -term studies, however, did not report any kidney stones as a side effect. In particular, some populations seemed to be more susceptible to adverse symptoms. Age was a significant predictor of adverse effects in a study with epileptic children. Consistently, another study also concluded that children younger than three years had a higher burden of side effects than those older than three years.

A classic KD has a 4: 1 ratio of fats to non-fats based on molecular mass. However, some studies reported compositions as an energy percentage. As such, direct comparisons of KDs between studies may not be made without investigating their definitions. Some studies also noticed on a temporary increase in LDL cholesterol during keto induction, although these are usually stabilized over time. Furthermore, the traditional KD initiation includes an initial fast period, followed by a gradual increase in calories.

In particular, a false KD -in mind has a considerably shorter time for ketosis than a gradual transition. However, children experience a greater burden of lethargy and hypoglycaemia under this regime. Other initiation strategies include initiation with full energy content with the intended fat-protein and carbohydrate ratio or a gradual increase in this ratio.

Triglycerides with medium chain (MCTs) have become a popular Supplement for KDS because they make a higher intake of proteins and carbohydrates possible while retaining ketonslings and efficacy in epilepsy treatment. In particular, MCTs are presented as a possible intervention to illuminate keto induction symptoms, although they can cause gastrointestinal needs in some people, if not gradually titrated. Available data suggest the benefits of engaged MCT supplementation with increased keton synthesis as an energy substrate in low glucose conditions.

Conclusions

All in all, passing symptoms related to keto induction are customary and various mechanisms have been proposed for these symptoms. The rated populations were very heterogeneous in terms of health status, age, diet strictness, initiation method, KD formulation, ad libitum nutrition, food choices and caloric disabilities.

Opposations to reduce keto induction symptoms include supplementation of ketone salts and MCTs, targeted electrolyte replacement (eg sodium/potassium) and avoiding conventional false initiation of KD. Although there is a physiological reason for ketonester and electrolyte supplementation, clinical studies are missing to confirm their efficacy. Short-term changes in the short term, such as increased LDL cholesterol, were reported in some studies, but generally resolved with persistent compliance. Further research is required to fill in existing knowledge gaps and to minimize the obstacles that prevent KD acceptance.