While many people do not experience significant side effects during the 5-day fasting mimicking diet, by the second or third day, some individuals report experiencing symptoms frequently seen with other prolonged fasting or ketogenic diets that may include:
Less common side effects may include:
- Brain fog
- Gut changes including constipation or diarrhea, and rarely nausea
- Muscle soreness
- Sleep difficulty
- Sugar cravings
Most of these symptoms are self-limiting and resolve either during or immediately after completion of the diet; however, for some they can last up to two weeks.
While autophagy—the breakdown and recycling of old damaged cells—may be responsible for some of these side effects, another probable cause can be what’s known as the keto flu.
The keto flu and its ill effects are caused by the body’s transition from burning sugar to burning fat for energy. Although it’s a temporary and natural reaction to entering ketosis, the symptoms can be too debilitating for some to get through.
Potential Remedies for the Keto Flu
Methods you can use that may ease symptoms of keto flu:
1) Stay hydrated (drink at least 64 fluid oz of water each day)
2) Increase electrolytes like sodium, potassium and magnesium, which will help you hold onto the water you’re drinking (you can add Himalayan sea salt to the soups, or drink a zero-calorie electrolyte water)
3) Get plenty of sleep on a consistent schedule (do your best, but it isn’t a problem if you don’t stay asleep the entire night)
4) Avoid strenuous exercise and activities, as these may increase the demand for energy and worsen symptoms.