General

Glycine & Fasting: Does It Break the Fast?

18 hours ago (edited)

I’ve been taking glycine in the evening to support sleep. Works well for me so far.

For a while, I was doing 16:8 fasting and I’m now thinking about getting back into it because of the potential autophagy benefits.

But here’s my question:

If I take glycine in the evening, does it break my fast and stop autophagy?

Also wondering what actually matters more:

Better sleep from glycine

or

Staying in a fasted state for autophagy benefits?

What would you prioritize?

Also open to any tips on what supplements are fine during fasting and which ones are better to avoid.

Autophagy
Fasting
Sleep

Please sign in to post a reply.

· 16 hours ago

@tino-wenderoth

Yes, it technically breaks your fast as it has calories and triggers some insulin response. But here's what I learned: when I skipped glycine to keep my fast "perfect," I'd sometimes lie awake for hours and feel like garbage the next day.

When I started taking it again during fasts, my sleep improved dramatically and I felt way better overall. Poor sleep screws with your hormones and recovery in ways that probably cancel out most fasting benefits anyway.

Only my 2 cents: I would take the glycine, get good sleep, and don't overthink it. The sleep quality win beats the minor fast-breaking downside by miles.

If you sleep fine without it, skip it. But if it's the difference between solid rest and stressing about amino acids all night, just take it and move on.

What do our fasting experts say?

@bastian-mayerhofer
@heiko-bartlog
@brgmn
@ronald-tenholte
@hadi-saleh
@matthias-buchhorn

· 7 hours ago

I skipped glycine during my FMD!

During my everyday intermittent fasting, I take it some days and some days I don't. I usually sleep well with or without glycine. I don't take these daily fastings too serious any more - if it's 12 or 16 hours - I'm just not hungry in the mornings 🤷‍♂️

· 3 hours ago

@tino-wenderoth @karol

I'd agree with Karol's take. Good sleep is a lot more beneficial than intermittent fasting, especially considering the following:

  1. The idea that macroautophagy ramps up during intermittent fasting goes back to an erroneous translation of mice data to humans due to different metabolism and lifespan. The actual timeframe is rather 48-72 hours for humans. That's why most fasting programms last for roughly 5-7 days. Macroautophagy is peaking around 72 hours and slowly recedes afterwards (generalizing a bit here).

  2. I do not recommend 16:8 IF to most of my clients anymore. There are, in fact, short-term benefits (like weight loss and improved insulin sensitivity) associated with it. The latest research, however, indicates what some researchers have suspected for a while: Not just the omission of breakfast is deleterious to long-term health outcomes (which has been shown in numerous studies), but the short eating window (≤8h) itself is harmful in the long run, with a 91% increased risk of CVD/Death.

    https://newsroom.heart.org/news/8-hour-time-restricted-eating-linked-to-a-91-higher-risk-of-cardiovascular-death

    This study is not fully published and peer-reviewed yet and has some (common) limitations, but seems to indicate that a 12-14h eating window seems a lot more beneficial in the long run.

I like to think of this development as "You can have your cake and eat it, too" as research seems to indicate that you can get the short-term benefits of IF with a 12-14h eating window while optimizing for long-term health and at the same time enjoying food without stressing out about an unnecessarily large daily fasting period.