IF & Exercise - How soon do I have to eat?

redimock

So, I've been experimenting with IF recently, and I really like it and think it's a great tool in my tool belt. Now that my kids are out of school for the summer, I'm going to make getting back to the gym a priority (yay child watch! ).

Anyway, usually when I do IF, it isn't a true fast, because I have my coffee with HWC for breakfast. When I go to the gym though, I plan to just be doing a water fast and break my fast afterwards. BUT, I still want to break my fast with my coffee & HWC, and wait until later in the day to eat actual food. Can I do this? I find exercise to be a natural appetite suppressant, so physically I am positive I can do it, but do I need to have protein right away after exercising?

Any advice would be greatly appreciated!

wabmester

There have been a bunch of studies that suggest "optimal" protein timing around exercise. Some discussion here:
http://caloriesproper.com/meal-frequency-intermittent-fasting-and-dietary-protein/

It depends on your goals. You'll probably burn some protein with the combination of fasting and exercise, but if your main goal is weight loss, then maybe that works for you. Not ideal if your goal is muscle gain.

redimock

Thanks @wabmester! For now my goal is fat loss, but I'd rather not sacrifice the muscle I do have because of stupid mistakes . What I gleaned from reading that link was that as long as I eat enough protein, I maybe don't need to worry about timing? I hope so! I suppose I can also experiment on myself and see how I feel, check measurements, etc....

My workouts are not going to be super intense in the beginning. Either a combo of cardio & yoga, or cardio & calisthenics, depending on who the yoga teacher is that day.

Foamroller

Op, As long as you intake adequate protein for your activity level some time during the day, you should be fine, IMO. The body is smart. It doesn't burn off skeletal muscle that easily.

The body has a protein turnover of about 300-400 gram/day. But a lot of that are amino acids that the body recycles. So the actual RDI ranges from ca 45-80 gr protein. BUT! Exercise level influence the P turnover. So erring on the higher side is probably Ok.

@wabmester. I have tried to look for methods or numbers that differentiate between fat free mass (FFM) and skeletal muscle. Without luck. How do they determine that? As I understand it, the body does quite some maintenance every day: regrowing hair, skin, repairing tissue etc. I mean, how do they measure that the FFM lost was actually skeletal muscle fiber and not less water weight or BM left in the tummy or some other variable like inflammation?

And also....what really happens to excessive intake of protein? I got dizzy trying to make sense of conflicting info...

Ty for your time.

Edit: Spellings. I really appreciate if you take the time to find out what I struggled with. If you don't have time., that's OK too

wabmester

In the primary experiment caloriesproper looked at, they used bioelectrical impedance to measure FFM, which, as you know, is sensitive to hydration. They took all their measurements after subjects voided their bladders and bowels.

DXA would be insensitive to hydration since it uses x-rays and measures tissue density, so it can distinguish between muscle, fat, bone, and organ tissue. Same with CT scans.

All protein is first converted to amino acids in the gut. Excess protein is stripped of nitrogen in the liver, and the resulting carbon skeleton can be used as a substrate for GNG or ketogenesis.

The nitrogen is excreted as waste -- either urea or ammonia. They measure the difference between nitrogen intake and excreted nitrogen to determine how much protein was used as amino acids vs oxidized. Negative nitrogen balance (more excreted than consumed) means you're burning muscle.

You can convert the excreted nitrogen in grams to protein grams (I think the multiplication factor is 6.25) to figure out how many grams of protein you burned.

Foamroller

ty for your answer!

Re dxa. I may be misinformed, but I think DXA can't distinguish between the blood inside muscle fiber (intra muscular) and the muscle fiber itself.

Which could imply that low carb diets and IF will show less FFM due to less water retention?

What I'm curious about is how can one determine if there has been a real loss of muscle fiber in one individual due to fex. dieting? I read somewhere that inactivity leads to a 1% loss of muscle fiber each year over age 60. I wonder how loss of LBM due to dieting stacks up in comparison?

Re excess protein. At what ratio does the body produce GNG or excrete in practical numbers. Let's say someone eats 100g over the need...what happens? And moreover...how much more protein does physical activity warrant over being sedentary?

Re nitrogen balance. I thought the body had a "pool" of available amino acids and that if needed to catabolic for extra energy,it would break down non vital tissue in an order of priority before burning vital tissue.

I don't mean to chip about this, but it seems so illogic to me that the body would preferably burn muscle fiber tissue (which is metabolically really hard to get) if there's STORED fat still available. I thought this IS the reason we store fat so easily, to spare muscle and organs during lean times?

Even the survivors of WW2 concentration camps were able to "work" through horrible conditions. If they really were weaning away at 25g muscle fiber a day for years...It just doesn't add up for me.

I'm sorry for rambling away and all my silly questions. I'd really like to understand this!

wabmester

The body is a dynamic system. Everything is always in flux. There is no "amino acid pool" -- it's just a concept associated with the continuous breakdown and rebuilding of muscle tissue -- that protein turnover you referenced.

Why would amino acids be used for fuel? Because we need glucose. Even when "keto-adapted," there is a constant need for glucose. It doesn't matter how much fat is available when a tissue is starved for glucose.

So if amino acids are used from the "pool" and not replenished from diet, we're in negative nitrogen balance, and there's less available for muscle building/rebuilding. That negative balance is something like 100g of protein after 24 hours of fasting.

If you eat enough protein to both offset that negative balance AND supply enough for your daily requirements, then I imagine you won't suffer any long-term muscle loss.

I doubt there's an easy way to quantify losses since there are so many factors. If we lose weight, we need less muscle to move that weight around, so rather than focusing on muscle loss, we should probably be more concerned about strength loss.

That's what I go by. I run and do bodyweight exercises pretty much every day, so I have daily metrics of speed, endurance, and strength. The stuff that really matters.

Foamroller

Ty for explaining to me. I really like it. I have been taking protein like crazy this year and have gained a lil bit of muscle. I can feel and see they're bigger. So maybe I hit the sweet spot of nutrient partitioning from jan-oct 2015, despite doing IF + exercise. I was weight stable but kept going down sizes. It was damned hard work, though.

I agree with you. The more I look into what aging is about...the more it looks like keeping muscle mass and having a functional aerobic capacity is an essential part of staying physically youthful. Someone said in a podcast that doing a "turkish getup" with a kettle bell or weight is a good litmus test. Being able to rise from the floor without too much strain. When people can't do it anymore, they inevitably end up in nursing homes.

Ty for being patient with me. And Ty for your contributions to this group

Which BW exercises do you do and how long each day?

wabmester

Here's my indoor gym. Various squats, lunges, and push ups. Till exhausted or bored.



And here's my outdoor gym. Pull ups, inverted rows, dips.