I only have until I start my new job to do extended fasts so I’m in a bit of a time crunch. I’m on day 5 of a fast rn. Debating if I should break it today to go to my friends party tomorrow.
So more specifically; are four 5-day fasts almost as good as two 10-day fasts?
In my experience one 10 day fast is more effective than two 5 day fasts with an eating break in between.
This is mostly because it takes 1 or 2 days for your body to really get into a “full fat burning mode” during a fast. If you take a break after 5 days, you reset the clock and then it takes another 1 to 2 days to get back into that full fat burning mode.
5 day + break + 5 day == 6 days of fat burning -vs-10 day fast == 8 days of fat burning
You’ll probably burn 33% more fat with the 10-day fast, than two 5-day fasts.
All of that said, a 10-day fast is boring. 5 days is tolerable. Do what feels right for you.
I find that I gain weight back a hell lot faster if I go off tangent after a long fast than if I went off plan for refeeding during multiple short fasts.
If you can stick with healthy refeeds and long fasts aren’t affecting your sleep I would do a long fast. It is pretty motivating to drop weight every day on a long fast.
I prefer longer fasts. Studies have shown that protein sparing is lessened in shorter fasts because it takes time for your body to transition into ketosis. A study of participants of a 10-day fast showed that their weight loss comprised of 40% fat loss, 25.2% “metabolic active lean tissue”, 26.4% water, and 8.4% muscle and liver glycogen.
Conclusion:
“A 10 day fast appears safe in healthy humans. Protein loss occurs in early fast but decreases as ketogenesis increases. Fasting combined with physical activity does not negatively impact muscle function. Future studies will need to confirm these first findings.”
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8718030/
It’s a tough question to answer with certainty. The CICO people will say it’s the same.
For your situation, the question is easier.
You would continue this fast because you are doing well and hypothetical 10 day fasts in the future may not go as well.
There wouldn’t be any research on this but I would suspect that 10 day fasts would have some mild metabolic slowing which I’ll assume recovers after eating again.