Eating for a Bigger Butt

The diet for bigger glutes is the same as any muscle building regimen.
"Bulking" up your muscles requires eating more calories than you burn. You don't want to eat a diet full of extra junk calories, stick to protein sources, whole grain carbohydrates, legumes, vegetables including non starchy varities, and fruits. 

You can add between 200-300 extra calories per day.  Everybody is different so gauge it after several to weeks, take notice of changes in measurement.  You might need to increase that amount if you are still burning too many calories to add extra muscles. Be care with this as after I lost of the weight I wanted and started focusing on bulking up my muscles, the extra wiggle room in my diet led to cravings.  Long story short, I gained 10 lbs of FAT! ( Granted there were some other things, such as a 3 week vacay without a gym that led to my demise)  This is why I must STRESS eating clean even though you can eat more.

Also to get a bigger booty you must be weight training with progressive overload to encourage your muscle fibers to grow.  Check out my butt building workout for ideas on which exercises to do.