K.R.
I think it is mostly a phase. My son (he'll be 3 in September)hardly eats, ever. There have been many nights right before bed where he eats an egg scrambled with shredded cheese and a Jennie-O hotdog. But, he does consistently gain weight (even if he is in the lower percentiles). His doctor told us to feed him whatever he wants, whenever he wants it.
Luckily he loves fruit and most veggies. We don't give him candy or most other sweets. He gets Teddy Grahams or Circus Cookies daily (grandparents care for him while we work, and they give him milk and "cookies" before naptime and periodically throughout the day).
Good luck!