carbo-load 
verb [no object] informal
Consume a large quantity of carbohydrates, especially in order to increase stores of glycogen in the muscles before taking part in a sporting event: I went to this place a while ago, to carbo-load for the triathlon it’s not unusual for athletes to start carbo-loading in the week leading up to the race...
- Around three days before the event start carbo-loading with the special products found in all cycle and sports stores.
- Mornings, pace yourself on a spiderweb of trails through the Pisgah National Forest; after lunch, sit in on talks by Nike pros and carbo-load on fresh-baked bread in the dining hall.
- The trout arrived firm and fresh, and thankfully the portion of potatoes was of a suitable but not excessive size, so that I was not confronted with enough spuds to carbo-load for a marathon.
Origin
1980s: from carbohydrate + load.