There is a large body of science which confirm, if you eat fat, you store it, if you eat Carbohydrates, you burn it.
This is consistent with human evolution because fats are quite rare in nature, so we have high storage efficiency 97%. If you eat 10g of fat, 9.7g is directly transported to your fat cells, without conversion. If your fat cells are biopsied, they can tell you if it's fish oil, or canola.
WHEREAS, if you want to to do denovolipogenesis, the conversion of CARBOHYDRATEs into Fats, you lose 30%, If you eat 10g, you can at best store 7. The human body HATES doing this. Because under natural conditions, it would represent a huge inefficiency.
You can see a huge difference in behavior for TRUE carnivores, A lion EATs a HUGE meal, then they sleep it off for several days.
Carnivores are mostly SEDENTARY the majority of their life. Whereas HUMANS and herbivores, have to eat regularly, because we do not store what "we're supposed" to be eating, Carbs.
In human evolution, When carbohydrates were plenty, this was the WARM seasons, so there is absolutely no reason to convert to fat for storage, generally, if you eat 15% more in carbs than your basal metabolism, all of that is converted to Heat or Activity. Because during that warm season, was when you should be getting stuff DONE, whatever required doing.
So, if you're STILL FAT, after all that exercise, it's not that you haven't gained muscle, it's because you're eating enough fats, such that your fat stores are growing on top of what minimal amount of muscles you've added.
Raw muscle growth absent special cases, genetic/ steroids, is extremely slow, 5lb-7lb per year, whereas FATs are RAPID, you can gain 1/4 lb a day if you can stomach it, again because the storage efficiency is so high.