I’ve seen this mentioned quite a few times on here & it seems like most people are a bit mis-informed or confused about this, so this is to help clarify:
skeletal muscle tissue is metabolically active tissue (just like the brain, heart, liver, etc)
now metabolically active doesn’t directly mean ‘fat burning’, it means that it requires more energy (calories) to operate, this is great because we can maniplulate muscle tissue by adding more, thus raising our metabolic rate
so somebody with a larger amount of muscle tissue will be metabolically in a better position to burn fat, than someone without much muscle tissue… therein lies the mis-understanding.
we know that to add mass, we need to add energy (caloric surplus) eat big to get big etc
we also know that to lose mass, we need to remove energy (caloric deficit), these are the fundamental laws of the universe that we cannot escape no matter how much we’d like to.
Now, the good news is that for a newbie, you CAN do both at the same time for a short period (usually between 3-6 months or so)
and while some people will ‘recomp’ (like tanks) by replacing the scale weight they’ve lost via fat, with new muscle tissue, thus pretty much staying at the same weight… this is rare.
fat loss is & will always be easier & faster than building new tissue for the very, very vast majority, so even for a newbie… in a caloric deficit, while losing fat, you should be able to build some new muscle tissue during that time, but the balance won’t be the same (for most people)
I see it very often when people are staying the same scale weight & just say “I’m losting fat & building muslce, so that’s my weight isn’t changing”… this is not the case for most people, they’re just simply not in a caloric deficit.
another point is that mass for mass muslce tissue is more dense than fat, so it will affect the scale, but at a relativeley small amout…
for example, for an overweight person, it should be easy to drop at least 2lbs per week if you’re on track correctly…
now as a newbie in a caloric surplus, you can be putting on anywhere between 0.5-1lb of tissue per week…
since you’re in a deficit, you can pretty much half that.
so, lets say you’re losing a good 2lbs of fat, and you’re also adding 0.5lbs of muslce per week, means you’d still be losing weight at approx 1.5lbs per week, while losing fat & building muslce at the same time…
the GREAT news is that the added muscle tissue is metabolically active, thus meaning it requires more energy to exist… in short, this means you get to eat MORE calories while burning fat/losing weight.
hope this helps, as people always seem to have the wrong end of the stick when refering to how muscle mass helps support fat loss.
it means you get to eat more overall food (calories) while losing weight, because your body/muscle tissue needs more energy than someone without the extra muscle tissue mass.
so in short, having extra muscle tissue doesn’t just magically burn fat tissue (that’s a mis-conception)… but it does put you in a better position to do so
hope this helps!