Why do triathletes do this?
Underfueling can be from many reasons - fear of gaining weight, wanting to lose weight, trying to be more "metabolically efficient," not knowing how to fuel, not feeling that (more) calories are needed, thinking sport nutrition is bad/unhealthy, not bringing enough energy/fluids, not planning stops accordingly, poor planning/feeling rushed to get in a workout or not knowing how much energy/fluids are needed. Certainly, underfueling does not enhance performance and consequently, not meeting energy and hydration needs can sabotage health.
Every time you just "get by" to check off a workout to say you did it, these are the workouts where you are not training smart. Consecutive long workouts where you just get by will not make your body prepared for race day.
First, learn how to ride your bike.
Get a good bike fit from an experienced fitter, improve your bike handling skills, learn how to sit on your saddle properly, ride comfortably and relaxed and improve your posture. By doing all of this, you will ride more efficiently, thus expending less energy.
Secondly, learn how to fuel for your longer workouts. Your body will thank you by giving you great health in training and a fitter, faster, stronger and more powerful body on race day.
-In cooler temps, you will find it easy to meet energy and fluid needs. In the winter months, you will find it super easy to digest and easily absorb almost any type of solid or sport nutrition food. But come hot weather, your gut becomes much more sensitive to what you put inside the belly (substance, volume and concentration) as the muscles and gut are competing for the same blood (and most of the time, the muscles win). Most athletes will find it necessary to consume less calories than normal in hotter temps but in order to ensure a steady effort, pacing must be appropriate.
-The first tweak in regard to summer fueling/hydrating is more of a change in routine than a change in habit. And boy oh boy, I know that triathletes do not like change. With the hotter temps, you will need to stop more frequently to refill bottles. Rationing your fluids so that you don't have to stop during a 5+ hour ride (because it takes times or will affect your overall speed/pace) is not ideal, yet time and time again, triathletes don't make the effort to stop. Limit your stops to no more than 10 minutes as you do not want your body to switch to recovery body. Make your stops quick - bathroom, refill bottles with sport nutrition powder/ice/water and then get back to doing work on two wheels. Be sure to plan your routes accordingly - if there are no places to refill bottles (water fountains or gas stations) consider loops or out and backs.
-The second tweak is making sure that you have enough easy-to-reach cages/hydration systems on your bike. There are many different set-ups as to where to place your cages but no matter where you put your bottles on your bike, you should have one primary bottle that you use to meet your fluid/energy/electrolyte needs (rotate bottles to keep this primary bottle stocked). Every triathlete should be skilled enough to grab, sip and rotate bottles (if this scares you - practice in a safe parking lot, not on the trainer, until this skill is mastered). If you are resorting to a straw-based hydration system because you are not comfortable grabbing bottles - you still need to know how to grab bottles to refill your straw-based hydration system. Grabbing bottles should be a skill that every triathlete is comfortable with in training, well before race day. You need to carry your nutrition with you so be sure to invest in 3-4 cages on your bike.
-Although I have seen all types of haphazard fueling strategies by all types of athletes, here is the most simple of sport nutrition advice to help you meet your needs during workouts over 90 minutes (or intense workouts over 60 minutes):
-->Bring 1 bottle sport drink for every 1 hour of riding. This could be anywhere from 150-300 calories depending on your hourly needs - be mindful that the concentration, carbohydrates in a specific volume of water, is extremely important in hot weather - less concentrated = easier digestion but this may require you dialing back your effort so you don't run out of energy too soon. As you may know, I prefer and advocate sport drinks/powders over solid food + electrolyte based-bottles for optimal digestion and absorption and a more simple execution.
-->Each sport drink bottle should have at least 400-600+mg of sodium. While there are several ways to monitor your electrolyte needs (pre/post weighing, sweat rate, urination, etc.), many athletes fall short on electrolytes (specifically sodium) by either taking in too much or too little but not always staying consistent. You can simply add salt to each bottle (1/8 tsp salt = ~290 mg) to increase your sodium intake, without a large bolus of salt being consumed all at once, per hour. Salt tabs may have a place but should be discussed with a sport dietitian on proper usage. Also be mindful that there are good salt-based electrolyte tabs/sticks on the market but also some that are not used properly by athletes due to being misinformed on how to use them.
-->Lastly, you need to add 1 bottle of ice cold water to your bike for sipping and cooling. Whereas in cooler temps (or the fall/spring) you may be just fine meeting your hydration needs each hour by finishing a 24-26 ounce bottle of sport drink each hour, in the summer heat, there's a good chance that you need up to 32-36 ounces of fluid per hour (this additional fluid does not have to be calorie-based fluids - water is just fine). Adding in the extra water can make a huge difference in terms of how you feel, absorb nutrition and hydrate during a workout. When you finish your water, this is typically a sign that you should be stopping soon to refill your bottles.
Example: If you are riding 3 hours, bring 2 bottles sport drink + 1 bottle ice cold water. Sip every 10-15 minutes, 3-5 big sips at a time. If you fall short on this or your terrain doesn't allow you to follow this regime, you can also do 2-3 sips every 7-8 minutes but never overchug to "make up" if you go too long without fueling/hydrating. Slowly catch up. Plan to stop around 2 hours to refill bottles to last another 2 hours.
-Your best fueling and hydrating plan in the summer is one that can be easy to execute, over and over again in training - hour after hour. Simple is best! Don't make your fueling and hydrating more complicated than it needs to be. Frequent and consistent intake is extremely important for optimizing digestion and absorption. In the case that your stomach is not accepting a drink, stop consuming calories for 10-15 minutes, sip occasionally on water throughout the next 10-15 minutes and back down on your effort/pace to let the gut settle.
-Tip: To prevent taste bud fatigue, you should have multiple flavors of your sport drink each hour. If you like eating a little solid food as you are training/racing, compliment the sweetness of a sport drink with something savory, like a peanut butter, chocolate, bacon or rich and bold-based food as opposed to something sweet, on top of your already sweet drink.