Recently I received this question from a reader:
This past weekend I did a century and had a bonk experience. I forgot my pack with my fuels, so I overdid the lunch with foods at a buffet restaurant all at once (mashed potatoes, broccoli rice casserole, mac and cheese, and salisbury steak – not the best options). There were 60 miles to go. At mile 90 I lost energy and went from 16-18 mph to about 12-14. I felt like I had enough to calories to get me there, but apparently not. Do you think this was from not refueling every hour, or did I just not fuel enough period?
Yes, eating a lot at once is very different that eating small amounts throughout the ride (which is what you normally do and what you intended to do). The difference is: when you eat a lot, your body has to divert more blood, energy, and oxygen to your gut to digest it – less to your legs/muscles. You may not have felt it this time, but that’s why athletes often feel like they are dragging immediately after eating too much. Then, once the food has become usable energy in your bloodstream (blood sugar), some will be used, but the rest has to be stored b/c it can’t all be used at once. A rise in blood sugar leads to a rise in insulin (hormone). Insulin will cause you to store it – stored as glycogen (good), others as fat (okay, but an inefficient energy source right anytime soon). Then, after all the insulin is pumped out to deal with too-much-blood-sugar-at-once, you’ll usually experience a low blood sugar, and since you didn’t have another fuel source ready for immediate energy, you bonked.
This is very different than small amounts, that are able to be used, consistently throughout a ride. This is also why it’s not a good idea when athletes save all their fuel for the 1/2 way point or the summit of their climb or ride, and then eat a bunch at once. Simply, it’s not about total calories at one time. It’s about the amount of carbs and fuel your body is able to use per hour – if not used, then stored. This amount is generally believed to be 40-60 grams of carbs per hour. It can also use “quick-acting” protein like whey powder efficiently when it’s in a ratio of 4:1 with carb (4 grams carbs to 1 gram protein). On longer rides like this, you can use other sources of slower carbs, protein, and fat in small amounts throughout the ride b/c you do have time to digest them – but over-loading at once will leave you with too much insulin in system and no new fuel source.
For rides over 5 hours, I recommend that you add the other sources of calories – protein and fats. These will help you recover overall calories AND avoid that nagging hollow-stomach feeling. But again, it’s small amounts over the course of the ride. Once you start adding more solid foods with proteins and fats, you have to be careful to use ones that you digest well and don’t cause stomach upset or cramping. For these longer adventures, I recommend continuing your normal fuel plan of 20-32 ounces fluid, 40-60 grams carbs, and adequate lytes (400-700 mg sodium, 100-300 mg potassium, 80-120 mg calcium, and 40-60 mg potassium) every hour. Then, add a easy-to-digest food or drink every 2 hours – many of my clients use sports bars, 1/2 PBs& Js, Ensure/Boost drinks, etc (you can include these in your calculation of total lytes as long as you’re consistent with consuming them). Again, don’t eat/drink too much at once.
It’s a lot of trial and error, but as you train with a Training Fuel plan, you’ll “dial in” the right sources and amounts for you!
Chris Legh Bonking Gatorade Commercial - I’m not promoting Gatorade specifically, but this is a great example of bonking and it gets me all pumped up to Fuel Right!
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