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Which Builds More Muscle: Fasted or Fed Workouts?

If you're in the gym, you're there to build muscle. But not all gym rats are trying to build muscle for the same reasons. You may be a powerlifter and are only concerned with raw strength. You may be trying to get shredded for a bodybuilding competition. Or you may only care about building the physique that intimidates other men and gets all the chicks. Figuring out why you're in the gym and what type of body you want to build begs the next question: what's the best type of workout to get the physique you really want?


Some fitness experts believe that fasted workouts are the way to go, while others insist that you have to feed your body constantly in order to really pack on the lean muscle. So which is it? Well, we're going to tackle those questions here today. We understand that experimenting on yourself can take time and be difficult to track, so let's take a look at what science has to say on the subject so that you can make up your mind about what to do.

The Science Which Supports Fasted Workouts

Fasted workouts are pretty hot button topic. The people who support fasted workouts are very passionate about their beliefs - and the people who decry them can seem even more passionate about their side of the argument. But who's right, and who's wrong?

If you're doing any sort of exercise after having not eaten for several hours, you are considered to be in a fasted state. Some consider it much more difficult to work out while fasting because muscle glycogen gets rapidly depleted. When this depletion happens, your muscles get wobbly and you don't have the energy or endurance to really push past your limits. Lots of people end up doing fewer reps, lifting lighter weight, or shortening their workout in general if they work out fasted. This can be especially hard if you're used to fed workouts and suddenly transition to fasted workouts.

But despite all of these limitations, and negatives, fasted workouts might be worth a try. If you are fasting and then suddenly put your body through intense physical activity, it's going to trigger a landslide of hormonal and physiological reactions in your body. It'll increase your insulin sensitivity to help you get leaner and store fewer of your calories as body fat. As a matter of fact, people who are insulin sensitive end up shoving more free-flowing glucose into their muscles as opposed to their insulin-resistant counterparts. This increased sensitivity builds up over time the more often you work out while fasted. If you're worried about metabolic diseases, if you're an endurance athlete, or if you know that you have a greater proportion of the type 1 slow twitch muscle fibers, you can get a more significant benefit from working out fasted.

But probably the biggest benefit from working out fasted is the growth hormone surge it produces. And you'll get a bigger surge with a longer fast. Trained athletes who have consulted with their physician before experimenting on themselves has seen growth hormone surges as high as 2,000% of their normal levels when fasting for 24 hours before workout. And in case you missed the memo, the more growth hormone you produce, the more muscle you make. It also helps slow down the aging process and makes you feel healthier, too.

Good Reasons for Fed Workouts

Of course, the old school method of shoving an ungodly amount of calories into your body before, during, and after workouts is pervasive in the fitness industry today. But just because the same people who tout this strategy may also believe things like "eating more cholesterol increases heart disease" or "men build muscle, women do cardio", that doesn't necessarily mean they're wrong about fed workouts. They have some reasons why they believe in the fed workout strategy, and those reasons go little something like this:

  • Fed workouts are safer than fasted workouts - if you're working out fasted, and if you're working out at the end of a particularly long fast, it can be dangerous. That's why we mention that little bit about consulting your physician a minute ago. When you fast, your body depletes its electrolytes very quickly. This can leave you feeling light-headed and dizzy. If you aren't careful, you're highly likely to push yourself too far and end up passing out right there on the gym floor.
  • Many still believe fasted workouts are catabolic - now, we aren't going to take an official stance on this one way or the other right now; there are so many studies out there, either side can point to something that they believe proves their argument right. But if you try both fasted and fed workouts and notice that one works better for your muscles than the other, then that's all the proof you need.
  • Fed workouts can make you feel more powerful - if you eat the right pre-workout meal or take the right pre-workout formula (or both), a fed workout can make you feel like superman. You'll have energy, endurance, and your muscles will feel strong with every push and pull of the weights. And if you're doing any sort of explosive, short burst workout - like MMA training or HIIT cardio for example - then fed workouts might be better for you. Fed workouts are also great for athletes whose muscles have a higher concentration of type 2 fast twitch muscle fibers.

You Really Don't Have to Pick a Side

At the end of the day, you'll probably do yourself more harm than good sticking to one type of workout over the other. Plan your workouts and your meals strategically to get the most benefit. Go fasted before you do endurance training or low weight, high rep workouts. Go ahead and workout in a fed state if you're planning to do explosive cardio or high weight, low rep work. If you try different things and tweak what needs to be tweaked, you will eventually find the perfect balance of fasted and fed workouts!

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