I think
www.bodybuilding.com forums would be a better place for your question, but as far as I know the 6 meal a day plan is primarily used to slow down your metabolism. If you take the food you eat from your traditional 3 and spread it over 6, you may gain a little more weight. Most people however just eat twice, three times the food an average person eats to gain weight/size in conjunction with working out. If you don't wanna work out at all you might be able to get away with eating completely healthy foods. If you're worried about going to the gym because of stunting your growth or something , either ask your doctor if he thinks it would , or eat a lot and do other things like pushups , situps , maybe a pair of light barbells.