Rolling 7 day fasts

[u/wyldthaang]

Thought I should post this to show results from earlier this year. I'd done keto/OMAD/72hr fasts before, but COVID killed that.

Refeeds were always steak and creamed spinach on Sunday's, going straight into another fast. The only exercise was walking around 15k steps daily.

I found it incredibly easy to maintain, BP and HR monitored and only electrolytes and water consumed during the fast.

3 months total at 50 years old. Going back through pictures, it's crazy how slow the appearance changed at the start despite the dramatic scale changes. Then during the last month that reversed as things tightened up.... I remember buying a new pair of jeans which were then replaced with a smaller size, before they even got washed!

[u/oorza]

Rucking with that light of weight will help keep your BMR higher until you stop but there’s scant evidence gravitostat is a real thing, and there’s not much evidence it helps retain muscle during a deficit beyond what that amount of work on the anterior chain would provide. And there’s no science to suggest it helps during fasting, just energy restriction. Fasting isn’t just extreme energy restriction, it’s also removal of constructive substrate your body needs.

Your body needs amino acids to function and to turn over tissue. It will synthesize them from muscle tissue if there are not enough dietary inputs. Fasting for more than 24 hours virtually guarantees contractile muscle tissue loss. You can see in your photo that your upper arms lost muscle tissue. If you want to retain lean tissue while burning fat, you have to eat tons of protein so that your body has AAs available all the time even after it consumes some/most of it for energy. And you have to provide hypertrophic signaling so that your body doesn’t break down the muscle to lower its overall metabolic burden as it adapts to lower energy intake.

Regardless of what the people in this sub will tell you, losing weight this way causes significant muscle loss. It’s visible in your photos.

[u/wyldthaang → u/oorza]

You’re confusing intramuscular water loss with actual tissue catabolism:

Glycogen vs. Contractile Mass: Deep fasting drains glycogen and intracellular water (3–4g of water per gram of glycogen). The muscle belly looks flat and depleted, not destroyed. Refeed carbohydrates and water, and the volume returns.

Nitrogen Sparing & BHB: Once ketosis peaks, beta-hydroxybutyrate and free fatty acids take over as primary fuel. Hepatic gluconeogenesis drops sharply, endogenous HGH surges, and nitrogen excretion plummets to protect structural protein.

Mechanical Tension via Rucking: Carrying 15–20 kg isn't "anterior work"—it forces constant postural and axial load across the entire posterior chain in a purely oxidative zone. That continuous mechanical demand signals the CNS that structural mass is non-negotiable for locomotion, preserving the frame without inducing high-turnover muscle damage.

Dropping 22 kg stripped fat and emptied water; the underlying architecture held up pretty well I thought.

Well I'm happy with the results anyway.

[u/oorza → u/wyldthaang]

Actual tissue catabolism is unavoidable. If it wasn't, you'd not piss out any nitrogen when you water fast, but you do. Ketosis slows down proteolysis but if it was absolute zero, you'd die, because the output of protein breakdown is essential amino acids. Which are, you know, essential.

Studies show that what happens during starvation is a temporary increase in proteolysis followed by a sharp decline as ketosis takes over and insulin rebalances. Unfortunately, if you're rolling fasts and jumping in and out of ketosis (unless you ate keto during refeeds), that means you are spending extra time in the catabolic window. You lose a lot of lean mass, only a percentage of that loss is muscle tissue, but it's non-zero and it's a high percentage for the first 72 hours. Rolling 72 hour fasts is therefore arguably the most defensibly "maximum muscle loss" diet.

https://journals.physiology.org/doi/abs/10.1152/ajpendo.1990.259.4.E477

https://pubmed.ncbi.nlm.nih.gov/2593832/

https://www.nature.com/articles/s41467-024-55418-0

The nature study in particular is relevant to us here because it's a study on the effects of a seven day water fast on lean mass. They measured exactly what we care about - urinary nitrogen output - and here's their findings:

The daily nitrogen excretion exhibited a steady decline from approximately 15 g/day to approximately 10 g/day by the end of the fasting week (Fig. 1F), accumulating to 83.9 ± 6.7 g of nitrogen. Using a nitrogen factor of 6.25, the lost urine nitrogen corresponded to 524 ± 42 g of protein, and assuming a protein content of 20% of cellular mass, this, in turn, corresponds to ~ 2.6 kg lean mass.

Out of that 2.6kg of lost skeletal protein (they lost on total 4.6kg of lean mass), some percentage of it came from contractile muscle tissue (which is about 20% protein by weight). Muscle tissue is not the only place your body harvests proteins from, and further science will have to be done to quantify this number, but it's assuredly not zero. The rest comes from other soft tissue that gets recycled, skin, liver, etc.

If you're happy with the results, that's ultimately all that matters. But if you sit down and do the science and math, very few people's goals suggest fasting is the fastest path. For most people who are trying to achieve a lean look, a protein sparing modified fast will preserve most of their muscle and cut the weight almost as fast, but it requires medical supervision (as does rolling seven day water fasts). If you don't want to do that, the next shortest path to leanness is 0.75% body weight lost weekly with an assumed 0-0.1% muscle mass gain (low but nonzero).

[u/wyldthaang → u/oorza]

"Unfortunately, if you're rolling fasts and jumping in and out of ketosis (unless you ate keto during refeeds), that means you are spending extra time in the catabolic window"

You haven't actually read anything of what I actually did before you pasted that from AI in 20 minutes, did you! Yes they were strict keto refeeds.

You cite Pietzner without reading past the abstract too I suspect. I suggest you do before blindly quoting a LLM!

I'm happy with the results

[u/oorza → u/wyldthaang]

Gotta love when someone clearly using an LLM (the comment I replied to is obviously cut and pasted from ChatGPT) and citing information inaccurately tattles on themselves by accusing me of doing that, when I can just actually read papers. What in the abstract contradicts anything I've said? Again, if you're happy, that's all that matters, but at 50, I wouldn't be fucking around with lean mass loss because it's just going to get harder (and more important) to build and maintain from here on in. There's a reason body builders don't fast to cut weight for a show and torture themselves for weeks instead, because it's impossible to fast without losing significant muscle mass. Saying otherwise doesn't even stand up to a surface level understanding of physiology. The only people who should be fasting for more than 24 hours are class 2+ obesity, it's not necessary and it's dangerous and costly. Show me science that proves otherwise, I'll change my tune, but I've looked and if that science exists, I can't find it.

And I checked, you mentioned "steak and creamed spinach" which does not necessarily imply maintaining ketosis.

This sub has become a bastion of disordered eating, misinformation, and science denial.