How many meals per day should I be eating to promote lean muscle?
Lean muscle is promoted through what you eat, but more based on how you workout. You might want to look into new forms of lifting, rep/set ranges and intensity.
Food/meals a day is influenced by how much you eat. Your body moves into a starvation state if you do not feed yourself enough, and can even break down muscle to sustain itself.
The best way to do this is by eating (as mentioned above) 5-6 meals a day with portions based off both body weight and activity level. Be sure to hit all the food groups- try to base it off of the food pyramid. Its generic, but it is because it works.