Fasting before working out?

tasha12004
tasha12004 Posts: 232 Member
edited November 21 in Food and Nutrition
Just curious,

So I recently had a trainer who told me that fasting before a workout (8-16 hours) can help burn more calories after the workout because of ketosis. Now I'm used to fasting about 16 hours, but that was before I started adding in exercise. I'm not sure how safe it is, or how effective it would be towards weight loss.

He also stated that you would still eat your planned meals and calories after your workout until an 8:00 Pm cut off.

Has anyone else heard of this? Or even tried this? Just want to make sure I'm being safe with my weight loss going forward.

Thanks,

OP

Replies

  • jayemes
    jayemes Posts: 865 Member
    You won't be in ketosis after an 8 hour fast.
    Eat before you work out if you want to or need to.
    I personally can't eat before I work out or I feel sick. I have coffee only.
    Weight loss is simply eating less than you burn. It has nothing to do with what you eat or when you eat it.
    My advice would be to ditch the trainer
  • tasha12004
    tasha12004 Posts: 232 Member
    jayemes wrote: »
    You won't be in ketosis after an 8 hour fast.
    Eat before you work out if you want to or need to.
    I personally can't eat before I work out or I feel sick. I have coffee only.
    Weight loss is simply eating less than you burn. It has nothing to do with what you eat or when you eat it.
    My advice would be to ditch the trainer



    Thank You, I appreciate the advice. It sucks when you have to question someone your paying to help you ..
  • cwolfman13
    cwolfman13 Posts: 41,865 Member
    Training fasted is something that a lot of endurance athletes do at times as it helps the body adapt to burning fat for fuel with long exercise bouts rather than solely relying on glycogen and carbs.

    It is a misinterpretation to say that you will be in ketosis and burn more calories after the fact...you simply get your body adapted to efficiently using fat for fuel on long endurance events so that you are less likely to bonk. You don't burn more net fat...your body constantly cycles between fat utilization and fat storage. You actually burn more fat for fuel when you're sleeping than anything else you do...but I don't hear anyone saying to make sure you take 3 hour naps daily to lose weight.

    I do quite a few fasted rides...I fuel if I'm going more than 20 miles typically. I'm in maintenance and I maintain because I eat maintenance...if fasted riding caused me to lose weight and burn more calories, I wouldn't be maintaining...
  • sijomial
    sijomial Posts: 19,809 Member
    edited September 2017
    Your trainer should stick to fitness advice - a field where, hopefully, they may have a little knowledge. (Might be worth checking their qualifications though.)

    Training fasted, or not, is irrelevant for weight loss unless it impacts, or improves, your exercise performance.

    Setting arbitrary times of day to stop eating doesn't make a lot sense for someone who is calorie counting. If it helped personal adherence to your calorie goal then maybe. But I bet that's not what they are thinking.

    You won't be in ketosis after a short fast, even if you were it's irrelevant for weight loss - that's still down to calorie balance.
  • J72FIT
    J72FIT Posts: 6,002 Member
    tasha12004 wrote: »
    jayemes wrote: »
    You won't be in ketosis after an 8 hour fast.
    Eat before you work out if you want to or need to.
    I personally can't eat before I work out or I feel sick. I have coffee only.
    Weight loss is simply eating less than you burn. It has nothing to do with what you eat or when you eat it.
    My advice would be to ditch the trainer



    Thank You, I appreciate the advice. It sucks when you have to question someone your paying to help you ..

    Your trainer is only qualified to train you, not give you nutrition advice...
  • rhtexasgal
    rhtexasgal Posts: 572 Member
    There is too much conflicting information for the for/against, with scientific back up. Therefore, do what works best for you. For me, personally, I get up at 5:00 am to get to the gym and for the most part, I don't eat or drink anything. Sometimes, I will mix a little protein powder with some cold coffee (a little reserve kept in the fridge from the morning before) if my tummy feels up to it or I know it is a big weight training morning. Otherwise, I wait to eat or drink anything until I am at work. So technically, I fast from about 7:00 p.m. from the night before to about 9:00 a.m. the following day, about 14 hours of fasting.
  • KirbySmith46
    KirbySmith46 Posts: 198 Member
    rhtexasgal wrote: »
    There is too much conflicting information for the for/against, with scientific back up. Therefore, do what works best for you. For me, personally, I get up at 5:00 am to get to the gym and for the most part, I don't eat or drink anything. Sometimes, I will mix a little protein powder with some cold coffee (a little reserve kept in the fridge from the morning before) if my tummy feels up to it or I know it is a big weight training morning. Otherwise, I wait to eat or drink anything until I am at work. So technically, I fast from about 7:00 p.m. from the night before to about 9:00 a.m. the following day, about 14 hours of fasting.

    Wow, that's my schedule exactly, except I'll have some black coffee first thing after waking up.
  • Kwoconnor
    Kwoconnor Posts: 39 Member
    I only take a berocca drink and creatine powder in the morning before working out. First meal starts after 12.
  • AMV91
    AMV91 Posts: 86 Member
    Fasted or not seems to be based on preference.

    I used to workout fasted if it was cardio or HIIT because I would feel like my food was a lead ball in my belly during. But for lifting if I did it fasted I would have to lift a fair bit lighter than I normally did.

    I currently do IF so I eat around 12pm until 8pm. I would do my cardio (I am recovering from a c section right now) around 11-11:30, then break my fast with a post workout meal. If I were lifting, I would eat my first meal at 12pm and then lift around 2-3, then eat again.

    Its really whatever you feel best doing.
  • Armywife04_21
    Armywife04_21 Posts: 60 Member
    I work out around 5:30am and I don't even think of food that early lol. I honestly can't imagine having a meal and then working out. As others have said, it really is a matter of preference and what works for you, all about your calorie defitcit.
  • stubbysticks
    stubbysticks Posts: 1,275 Member
    Look up "intermittent fasting" - I think most recently I saw an article on Nerd Fitness that explained it pretty well. It's a valid method of eating & many athletes/bodybuilders swear by it. I don't know that your trainer had the details correct - you won't go into ketosis after 16 h - but it's not complete BS. Fasting cardio can also help train your body to use body fat for fuel instead of carbs from the food you eat.

    I'm currently following an IF plan that looks exactly like yours, 16/8 where 16h is fasting & I eat within an 8h window each day...but I'm doing it for simplicity's sake. Nutrition has been my challenge in recent years & it's way easier to plan two meals than three. With the shorter feeding window, overeating is far less likely to put me over my calorie target for the day. What I'm finding is that it's virtually impossible for me to negate my calorie deficit each day so it's working out great.

    But everyone is different, I'd suggest sticking it out for at least a couple of weeks before you decide to do something else to give it a fair shot :)
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