Kcals >>>>>>> macros >>> food sources >> timing > everything else
With regards to fat loss and hypertrophy, unless you are a rank beginner or returning after a layoff from resistance training (muscle memory), overall calories are of utmost importance. Put another way, unless you are in a caloric surplus for an extended period of time, no meaningful muscle gain will occur. Unless you are in a caloric deficit for an extended period of time, no meaningful fat loss will occur. I will note that fat loss happens much faster than muscle gain though. If a client has sufficient muscle, I can probably get them peeled in ~16 weeks.
Side note: No, you should not alternate lean mass gaining and fat loss phases by the week. This question has been asked a bajillion times. It is not sufficient time for meaningful hypertrophy or fat loss to happen. ***Definitely not meaningful hypertrophy.
The next most important (but much less important) is macronutrients. Specifically, you want to consume sufficient protein (~1 gram per pound of lean body mass) to maximize hypertrophy during a caloric surplus and minimize muscle loss during a caloric deficit. It’s probably a good idea (hormones, fat soluble vitamins) to set fat intake to at least 50 grams/day. Allocate the remaining calories to carbs (fuel training).
With regards to food sources, try to stick with high quality protein sources (contains all essential amino acids) such as chicken, beef, turkey, pork, eggs, fish, whey, and milk. Make sure you consume a couple servings of fruits and vegetables (vitamins, micronutrients, fiber) per day.
With regards to timing, getting a protein bolus of at least 20 grams every ~4-5 hours while awake is likely sufficient. If you’re intermittent fasting, limiting your protein intake to 3 meals (e.g. 8 am, 12 pm, 4 pm) around an 8 hour feeding window is probably fine. You should consume a bolus (at least 20 grams) of protein within your peri-workout window—from 1-2 before training to 1-2 hours after training.
“Everything else” encompasses supplements like creatine and caffeine.