I suppose we need extra energy for both lifting weights at the gym in order to stimulate mass building AND the actual process of mass building between gym sessions.

But I can't find good articles that distinguish between the two: how much of that extra energy goes to lifting and how much to building? Is it 50/50? Is there any research on this topic?

  • I don't think there is anything wrong with asking a purely academic question, but I have two (very similar) questions for you in return: 1) How would you research this? 2) Why does it matter?
    – Raditz_35
    Aug 6, 2018 at 14:34
  • Scientists often come up with super smart ways of testing things, I have no idea how to research that but that doesn't mean there's no way to do it. It doesn't have much practical importance to me, I'm still curious though.
    – drake035
    Aug 6, 2018 at 15:12
  • You have to be super careful though when asking for scientific research in the context of fitness. It's not an exact science. Tbo, I wouldn't trust anyone claming that they have a number that answers your question unless the error bars are really big to the point of the answer being meaningless
    – Raditz_35
    Aug 6, 2018 at 15:19
  • Well you could say that about pretty much any piece of research isn't it :D
    – drake035
    Aug 6, 2018 at 17:26

2 Answers 2


If you're talking about the extra energy that you would consume during a bulk phase compared with a cut phase, then the entirety of it goes towards getting bigger, because while your workouts do consume a lot of energy, you're doing that regardless of whether you're in a bulk or cut phase.

E.g. Let's say you consume 4300kcal/day during a bulk phase and 3300kcal/day during a cut. Here's where those calories might go.

Bulk: 2300kcal base metabolic rate, 500kcal burned during workouts, 1000kcal burned during other daily activities, giving you a 500kcal surplus that goes towards getting bigger.

Cut: 2300kcal base metabolic rate, 500kcal burned during workouts, 1000kcal burned during other daily activities, giving you a 500kcal deficit that causes you to burn fat.


It’s pretty much exclusively for adding mass as opposed to energy in the gym. You can always optimize the timing of your meals/snacks for energy, and you can also utilize preworkout supplements if your energy levels aren’t right when you get to the gym. Even the most intense training sessions aren’t going to require a huge amount of calories in the moment, so the idea that you need the extra energy for the workout is just silly.

  • Using an energy expenditure calculator, I determine that my workouts expend around 500kcal. That's pretty significant. (But that number would obviously be far lower for someone who only does, say, bicep curls, so this is dependent on actually lifting heavy weights.) Aug 7, 2018 at 0:51
  • 1
    @DavidScarlett - Sure, but the burning of those 500 calories isn't going to be functionally different whether bulking, maintaining, or cutting. Bulking is about a caloric surplus on a daily basis where working out is a relatively short activity by comparison (8-12 hours vs 1). All of that is to say that eating a little extra over the course of a day isn't going to provide any notable extra energy for a workout, at the very best you're looking at a marginal difference. Aug 7, 2018 at 12:35
  • Ah, right. I thought you meant that the calories burned during exercise weren't significant, but if you actually meant that there's no difference in calories burned during exercise between bulk/cut/maintain phases, then we're on the same page. Aug 8, 2018 at 0:11

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