Follow on from my Intermittent Fasting Diet Explained blog, because people don't just do the restricted time eating windows. They also may perform cardio or their workouts first thing in the morning to try and burn as much fat as possible by working out on an empty stomach.
The reasons why the data supports this is because in the morning your insulin levels are low. Insulin is responsible for keeping your fat stores and prevents you from utilising this as an energy store. So in the morning when insulin levels are lower it's easier for your body to utilise these fat stores for energy.
Second reason is that glycogen levels are also low in the morning. Because you've gone 9+ hours without any food. Glycogen is our bodies stored carbohydrate energy source. The theory is doing cardio or your workouts in the morning will utilise and use your fat stores so you'll burn more fat. Kinda making perfect sense at the moment, but that's not the whole picture *enter dramatic music*.
The fact is that just because you burn more fat during the session fasted it doesn't mean that you'll burn more fat overall, in a 24 hour period.
This is because what happens is afterwards your body swaps it's perfected energy source, so if you're using more fat for energy afterwards your body will use glycogen stores. If you're in a fed period your body will use glycogen energy during the exercise and then it's fat stores afterwards.
What does the research say? Well a study took 20 young women and put them in a 500 calorie deficit. They then participates in 1 hour of cardio performed 3 time a week, one group was fed and another fasted. The result was that there was no difference in fat loss between the groups. But both found significant fat loss (due to being in the deficit). It was however only run for 4 weeks which is quite short. Maybe there'll be a difference in a longer period of time, who knows.
There's some other points to note, not just the physical side. In the morning people do find that working out they feel energised for the day. It wakes them up and by completing a workout they're more primed to go out there and smash it. On the other side people who are fed are fuelled better for the workout and can perform better for that given workout. They can time their nutrients and fuel by having cards or fruit to give them that extra boost.
Bottom line is, do what fits your lifestyle and what you prefer. There's no right or wrong answer with regards being fed or not. What is important is if you want to achieve fat loss you're in a calorie deficit.
That's it for me today.
Thanks
Cameron
Additional Sources
Jeff Nippard - Does FASTED Cardio Burn More Fat? (What The Science Says)
(https://www.youtube.com/watch?v=IEbWdoceH-A)
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