A very filling snack:
Large pitted dates
Raw almonds or cashews
Organic peanut butter
Grab a date, shove an almond or cashew into the middle and cover it with some peanut butter.
Other snack ideas:
Hummus and vegetables
Dried fruits with almond butter
Banana with peanut butter and some nuts
Homemade granola with organic whole milk
Try to fill up on foods that combine protein with fat. Avoid white sugar or high fructose corn syrup. Avoid white flour or grains that are overly processed.