I wake up at about 11am and head off to the gym an hour later. I do 1 hour cardio 1 hour weights... I am 145 pounds 170cm tall and female.... I sometimes do fasted cardio to burn from direct fat (aim is to lose weight and gain muscle), however want to know science behind it? like is fasted cardio bad for muscle gain? if I do eat breakfast ill eat a protein shake, banana and some mixed berries. is this okay

  • How about simply eating when you're hungry? And fruits when you simply feel like munching on something? :) Commented Jul 29, 2014 at 23:51

4 Answers 4


Your body basically uses three things for energy: carbohydrates, fats, and proteins, in that order. The way it works ideally: when you run low on carbohydrates, the body burns fat for fuel. When you run low on fat, it moves on to protein, aka muscle loss.

In reality, your body uses a combination of the 3 for energy at any given time, and there are ways to optimize fat loss and reduce muscle loss (high protein intake, weight-training, reduced carbs).

When you sleep, or you're in a fasted state, your body uses up its stored carbohydrates for energy. As well as amino acids and glucose. This is great for fat-loss, and studies show an increase of about 20% fat loss in a fastest state.

The problem: the lack of amino acids can make gaining muscle more difficult. It's important to consume protein after cardio (about 30 grams within 30 minutes), particularly a fast-acting protein like whey or egg. This will replenish your store of amino acids and improve your recovery time.

If you go straight from cardio to weightlifting without consuming enough protein, your muscle gains will be poor. I recommend alternating the days that you do cardio and weights, or opting for weights before cardio if possible. Your muscles act like a sponge after a workout, which also makes it important to consume protein (any any supplements you might take) immediately after weights.

It may be a good idea to also alternate fasting cardio with non-fasted cardio. If you take in some carbs/protein before your cardio, you'll likely have improved performance at the cost of some fat loss. Use the opportunity to do some HIIT - more bang for your buck.


Your breakfast sounds well. Some berries, banana and a protein shake sound excellent as in right proportions it won't make you feel too full, but will give you the energy for the most part of the day.

I try not to eat at least an hour before and after a work out. I might have a small portion of a protein shake right after a work out as it helps muscle to rehabilitate. So I can do the same work out routine the very next day and won't feel sore.


if weight loss is your goal then it really does not matter as weight loss is all about HOW MUCH or how many total calories you eat but...

eating before may give you an energy boost to work harder and longer resulting in more calorie burn or...

you can NOT eat before workout and burn more fat since your body has to rely on that for energy instead of the carbs/calories you just ate so again with that said..

it doesnt matter WHEN but how much you eat overall for the day


There is a very small (but non-zero) benefit from fasted cardio. Perhaps a more important question is what regimen is going to make you feel the best during your workout:

  • if you have food in your stomach, are you nauseated? Does it depend on quantity and/or type?
  • if you don't have food prior to training, do you have sufficient energy to get through the workout?

These are probably more important things to worry about. (For me, as an example, if I'm training within an hour, I won't eat, I'll just hydrate like crazy. More than that, I'll have something to eat so I won't get hungry mid-workout.) Try logging your eating/workout regimes in a diary so you can review later and see what works best.

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