I don’t believe the subjects of those fasting studies were already in ketosis prior to fasting. Being deep in ketosis prior to a fast should reduce the need for gluconeogenesis and minimize lean tissue loss.
My own personal opinion is that if you have a lot of excess weight on your body, you can be more aggressive with it and see really positive results (I have) but it’s of less use if you’re already pretty lean.
Currently seeing good results with a Mid afternoon to late evening eating window, and skipping breakfast.
I personally do IF. Depending on the day it’s either 18:6 or 16:8 with the occasional OMAD or full day fast thrown in.
Before keto and IF, I was a breakfast eater. I NEVER skipped it before. If I did, my mind would be sluggish, and my memory would be non-existent. I can actually say that I haven’t had a meal before noon all decade
I think it was on a 2KD podcast where this discrepancy was talked about. What I recall:
- Dr Fung’s patients are typically diabetic and obese
- Dr Phinney worked with young athletes with a low lean body fat
According to the Alpert study (https://blog.2keto.com/alpert-2005/), we can use 31.5 kcal / lb of body fat. More according to Dr Fung but he didn’t provide an exact number.
For an obese person, that should be plenty. For a lean person, likely not nearly enough so the extra energy has to come from somewhere. So, depending on the person, they are both right.
Do I fast everyday?
Nope. My eating is now 2mad thru years of eating healthy.
but when I found my healthy eating I never ‘fasted’ or put me ‘locked into any IF time windows’.
I eat 2 times a day, maybe 1 and maybe almost nothing another, and then I might eat 3-4-5 times a day.
I eat when hungry. Do not eat when not. So no I do not fast everyday at all in the ‘terms of IF fasting and what it entails’ at all.
I like to eat LOL if hungry I do just that hasn’t failed me yet
That makes a lot of sense.
When you’re fasting, you’re going to burn whatever you’ve got. (Whatever you’re made of.)
A 400 lb person with 100 lb of lean body mass is going to have very different results compared to a 150 lb person with 135 lb lean body mass.