Heavy lifting on fasting days

This topic contains 5 replies, has 5 voices, and was last updated by  diverdog 6 years, 8 months ago.

Viewing 8 posts - 1 through 8 (of 8 total)

  • I do a lot of heavy lifting, such as deadlifts, squats, bench press, pullups and Olympic style lifts. I’m talking weights North of 150kg for many of the lifts. I’d like to hear some opinions on this type of training especially on fast days. I’ve been having between 600 and 700 calories in two meals 12+ hours apart on Mondays and Thursdays. Those days are usually my heaviest lifting days with deadlifts on Mondays and Squats on Thursdays.

    Did you lift then ? How did you feel?

    I’d love to see this thread continued. My running endurance is fine on FD, in fact seems to have improved pace, energy, and overall how I feel (went from running 2-3 miles at a time to 4-6 and reduced pace by 30+seconds/mile), but lifting weights kills me. The two times I’ve tried on FD I’ve really struggled later in the day. Today, paying extra attention to my hydration, I got the major shakes (like low blood sugar) and brain fog that lasted through me breaking my fast at dinner. I’m feeling ok now though. Lifting on NFD has gone just fine.

    Anyone care to offer thoughts on the different types of energy expenditure for weight lifting? In the form of fast twitch vs. slow twitch muscles?

    I’m not new to lifting or HIIT – years ago I was a super strong rock climber, did boot camp classes regularly for 7-8 years including (mostly) through pregnancy, and I’ve been doing fitnessblender fairly regularly at home. This is my second month fasting. I’ve been running since I started cross country at 14 years old, 22 years ago (gosh that makes me feel old). 🙂
    Thanks for any input or thoughts anyone!!!


    First off if you’ve only been fasting for 2 months your liver is only just starting to get used to the concept. I noticed a decided difference after 6 months. So give yourself another 4 months to get your liver efficiently accessing stored fat and being able to convert that to glucose and ketones. I do a lot of bike riding, sometimes in a fasted state.

    Conventional wisdom says weight training should be done in the afternoon. However if you are attempting to weight train while fasting then I would suggest that early morning will be best. My logic? While fasting you are basically depleting stored glycogen, both in the liver and in your muscles. As the day progresses these stores are depleted. High intensity weight lifting is an anaerobic activity and taps into your stored muscular glycogen without the need for oxygen. If you’ve got very little glycogen left your asking for trouble.

    Last night was the end of my fast day. My BG level was 3.7mmol/L. Unusually low but I felt fine. This morning when I got up my BG was 4.7mmol/L. It had gone up overnight. So overnight my liver was working overtime to replenish my glycogen levels and just before I got up (about 5am) it started ramping up my blood glucose levels.

    For those reasons Im suggesting that you should try doing weight training in the morning. Lower intensity endurance training where youre operating at 75-85% of your normal non fasted state, no problems your liver’s ketone production should be able to cope once you have keto adapted.

    Try a morning session and see what happens.

    Thanks for the response Bigbooty! I LOVE bike riding, but get limited opportunities to do so. Running is easier for me to do, and actually I can now run longer and faster on fasting days than I could before, so I thought maybe my liver had already adapted. Even lifting what I considered very light turned out bad for me – someone mentioned taking BCAA’s to help your muscles replenish some. Actually I had done my lifting morning, but was later in the day that I felt really bad, so it wasn’t getting through the workout but my body recovering… maybe?

    I had read about bulletproof coffee to help kickstart the body into keto mode – is this something you have experience with? Of course, it would have to be lowered in quantity or portions to fit into a FD.

    Thanks again!

    Yes I suspect that as a result of your workout you had depleted your muscle glycogen. The replacement and top up of muscle glycogen takes hours, so that may explain the crash and burn feeling you experienced in the afternoon. Im not sure taking BCAAs will help as such but I could be wrong. I know that sometimes after a heavy bike ride Im screaming for some tofu (I like tofu as my go to protein) but on other occasions Im not even hungry.

    At a lower intensity, like the running you described, if you have a well operating liver system then your liver should be able to supply enough ketones to keep you going. You wont completely deplete your stored glycogen. For the high intensity weightlifting Im not sure how you can get around that crash and burn feeling/problem? Do you HAVE TO do weight training while in a fasted state?

    I don’t think bulletproof coffee will put you into keto mode as such, but will help maintain you in a keto state while supplying you with calories. A lack of carbs (and to a lesser extent protein) will put you into keto mode. I do not eat a keto diet. I do however water fast once a week for 36 hours but allow myself two cups of coffee with milk. I enter ketosis after 24 hours (I measure this with a keto meter). Now here is the weird bit. After I go to sleep I will at some point drop out of ketosis. I suspect it is at about 5am when the “dawn effect” kicks in. At this point the body ramps up glucose production to ready your body for the days activity. If I continue to fast for a second day (I don’t do this any more) I quickly flip over to ketosis again.

    J Ray, if you are training really heavy I assume your rep range is <5 and most likely 1-3? If so you are mainly training the nervous system to recruit muscle fiber more efficiently and training while fasted should be OK. However I don’t know that it offers any advantages. For higher rep ranges where muscle damage occurs I would definitely eat protein before and after lifting to maximise recovery and repair.

    Oop’s I meant to direct the above post to free radical

Viewing 8 posts - 1 through 8 (of 8 total)

You must be logged in to reply.