I recently learned that consuming pre-workout (LIT AF) and water will indeed break my fast.

For the past 2 weeks, I have been waking up early to go get a early morning lift (Push, pull, legs is my usually 3 day routine). While after a workout, I will opt out of eating until 2:00pm, and finish my feasting at 10:00pm.

Since taking pre-workout at 6:30am will technically break my fast, is there any point for me to fast until 2:00pm or should I just go ahead and eat after my workout?

Will there be any benefit to this? I realize coffee is a solution instead of pre-workout but I like the focus and energy I get from pre-workout. It also gets me motivated in the morning to go to the gym.

  • Welcome to Physical Fitness Stack Exchange! Welcome to Physical Fitness! What's the purpose of your fast? Weight loss?
    – Cullub
    Aug 5, 2019 at 17:40
  • Yes, weight loss. I've have been lifting for quite some time now and have a solid amount of muscle and strength that is constantly being covered with fat. My diet has now always been the best but last month, I started to clean up my diet and noticed nice benefits. Aug 5, 2019 at 17:43
  • Nice! Not sure that I can post a real answer here, but You Lose Weight in the Kitchen; Gain Health in the Gym
    – Cullub
    Aug 5, 2019 at 17:55

3 Answers 3


According to this forum here, the general opinion seems to be that as long as my pre-workout is under 50 kcals then my insulin levels should NOT spike and there fore would not break my fast.

I would think that waiting until 2:00pm to eat will still have benefit since up until 2pm, my body will still be in a fasted state. Could anyone help me confirm this?

Side Note - I love working out in the mornings on a empty stomach, with nothing but pre-workout. I have not noticed much downside to it compared to when I train in the evening.

  • I looked at the forum you mentioned. Seems like a bunch of people with lots of opinions. Peter Attia, Jason Fung,Dr. Rhonda Patrick, or Dr. Satchidananda Panda are people who would know the answer to your question. However, I can't point you to an exact location where any of them have discussed your specific question. If you really want to know, you can buy one of the continuous glucose monitors recommended by Peter Attia.
    – Chris
    Aug 9, 2019 at 4:00

What you are doing is actually Time Restricted Eatting. This is often confused with Intermittent fasting. The distinction is important.

I've been doing Time Restricted Eatting for a few months. I finish eating around 7 pm, and I work out at about 10 am, after coffee. I eat my first meal of the day at noon. So, I'm working out on an empty stomach. However, I'm just as strong. I was completely amazed when I first tried this. I would encourage you to try it as well.

I decided to try this approach after listening to people like Peter Attia, Jason Fung, and Dr. Satchidananda Panda. I don't want to pretend to understand biochemistry, but here is my best attempt at summarizing their information. If you workout in the morning before you eat, then you are partly in Ketosis. The advantage of working out in Ketosis is that you burn fat while you workout. You can't burn fat if you have food in your stomach. It is biochemically impossible.

It was a huge leap into the unknown when I first tried working out before my first meal. I can't say it will work for you, but it is definitely worth a try.


If your goal is to improve your strength or lose weight, then do not fast anytime near your workout time (before or after) as this is the most important time for nutrients.

The saying, "Breakfast is the most important meal of the day," is not just a saying - it's a fact. The reason you need to break your fast before your workout is manyfold.

First, your body needs available ATP to perform the workout. If your body has no available ATP because you didn't eat for a long time before your workout, it will pull it from the quickest available resource, which is your muscles, not your fat.

Second, similar to the first point, is that your body makes the most efficient use of nutrients for recovery immediately following a workout. If there are no nutrients with which to deliver for recovery, your recovery process is sabotaged, restricting gains and limiting insulin spikes and protein synthesis.

Third, there may be nothing more damaging to metabolism than fasting. When you fast, your body is going into nutrient conservation mode and is more likely to put the nutrients you do consume into fat than to where you want them to go - your muscle. Metabolism is where real muscle gain and weight loss occur. Metabolism is responsible for natural protein synthesis, essential for muscle gains, and also sets the level of passive fat burning.

I think only you can answer the first part of your question on if it makes sense. In order for me to answer that, I'd need to know why you fast - religious purposes? Outside of religious purposes, fasting is not a good tool for most health goals.

IF you're going to fast anyway, and if your goal is either strength gains or weight loss, then you should time your fast furthest away from your workouts as possible, which for you looks to be the evening.

  • The person asking the question is not fasting. They are doing time restricted eating (TRE). Fasting has been around for ages, of course. TRE is a more recent notion, and since TRE is new, it gets confused with fasting. However, the two are distinct in many ways. In TRE, you schedule your eating to coincide with the circadian rhythm. It turns out that in your 24 hour circadian rhythm there is a window of about eight hours when your digestive system is functioning at optimal efficiency. In TRE, you fit your eating into this window of optimally efficient digestion.
    – Chris
    Aug 8, 2019 at 22:21

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