Friendly conversation ahead...
...As long as you're essentially dieting, you're never going to make any gains in lean muscle or gains in the gym. Fasting as much as you are talking about doing is 100% totally counterproductive to weight training and making gains. You may even start... or eventually will slip backwards as sarcopenia robs you of muscle each and every year as it does to all humans.
Aren't muscle gain and muscle loss the results of exercise or lack of exercise, and not diet or fasting?
And why would we burn muscle and bone when fasting, rather than stored fat?
Consider:
https://www.ncbi.nlm...ubmed/20300080/
Here, researchers studied humans who underwent 70 days of alternate daily fasting (ADF: eat one day; fast the next). And their fat free mass started at 52.0 kg, and ended at 51.9 kg. They didn't lose lean weight (bone, muscle.), they lost fat.
Fat exists, in part, to be utilized during times of food scarcity. Why would the human body, evolved as it has over hundreds of thousands of years, store excess energy as fat, and then right turn around and burn up protein when starving?
Protein is functional tissue -- it's bone, it's muscle, and it's needed to help us find food.
Fat is stored energy for times when we can't; stored excess fat is how our ancestors survived starvation. Nate will burn fat when he fasts, he won't burn much muscle and bone.
And we aren't the only animals that burn fat for energy when fasting. All animals do it -- we eat our own internally stored fat. Animals don't waste muscle and bone, and especially we don't waste muscle and bone while simultaneously holding onto fat stores when starving and forced to use muscles and bones when foraging and hunting.
Also if CRON doesn't translate into humans like mice, then intermittent fasting can be considered CRON-LITE and won't add decades to your life...… It just doesn't work in humans. Consensus seems to be something like 2 additional years.
EDIT: I know fasting improves some biomarkers, but big whoop if you're skinny and weak and old. My $0.02.
Researchers can't study the effects of CR on human lifespan extension because it's too hard. But going out on a limb here, CR extends lifespan in just about every other species tested. So why would humans be exceptional? Why would we, of all other species, fail to have adapted mechanisms to extend lifespan via CR, fasting, and food deprivation?
We did, you say, but we only get two extra years. Where are you getting the idea that consensus says CR extends human lifespan by two years? What consensus?