The mid-workout feast-and-bonk is a fueling mistake most endurance athletes make at some point in their training careers. Perhaps it's something you've felt before: you don't eat enough during the event or training, become hungry by the halfway point, then eat too much in an effort to replenish calories. Cue mid-ride feast-and-bonk.
If you spend long hours training, you can easily fall into this trap, from not packing enough food for the workout to forgetting to eat it while you're training. Don't let this hinder your performance. Instead, learn why this endurance nutrition mistake happens and figure out how you can avoid it.
Eating a lot at once is different physiologically than eating small amounts throughout the workout. When you don't eat enough each hour—and instead wait to replenish—you're training with sub-optimal fueling and create a deficit that is difficult to overcome. Although you can eat a lot of food at once, it's unlikely this will give your body the 300 to 400 calories per hour you need. Give your body the fuel it needs for the next hour, not for the hours that have already passed.
Playing catch-up not only leaves you depleted of necessary calories, but also forces your body to work even harder to digest the food. To digest, it must divert more blood, energy, and oxygen to your gut and less to your legs and other muscles. This is why athletes feel like they are dragging immediately after eating too much.
Once the food has become usable energy in your bloodstream (blood sugar), some of it is used immediately. However, your body can't use all of it at once. There's a limit to how much your body can absorb, metabolize, and use per hour, especially when working hard.
Much of the nutrients will be stored because your body can't use it right then—a rise in blood sugar can then lead to a rise in insulin (the hormone responsible for shuttling sugar from the blood into the cells). But, because the insulin can't shuttle all the sugar at once, you begin to experience low blood sugar, which causes the lack of energy. That's when you bonk or hit the wall.
Your training sessions don't have to feel like this. Fueling consistently, with foods and drinks in small amounts, creates a constant flow of energy and stable blood sugar levels.