My body gets to that point every summer when I'm working outside for at least 10 hours a day in the sunshine and heat. It's good! Just feed your body some extra healthy calories and you'll be fine. Eating small amounts during the day will help keep up the metabolism boost, too.
Just don't snack on carbs alone, in my opinion. Add some fiber and protein in there.. one of my favorite snacks is celery or carrots and some peanut butter.
Hopefully you are enjoying your activities as much as your metabolism is.
