Sometimes your training volume or intensity takes a dip. Sometimes you fall off the wagon, or maybe you choose to depart the wagon for greener pastures while life throws a few storms at you. Eventually, though, we usually make a return to training and start to take workouts more seriously again—more volume, more intensity, longer sessions, multiple sessions, tougher conditions. When that happens, you need to be sure your diet calculations are in line with serious training.

Some of the things you need to pay attention to—and that we’ll go into in greater detail: Increased training intensity changes your diet and carb needs both inside and outside of training; increased volume also changes your diet needs; both increased intensity and volume increase your need for protein; and your sweat physiology (and acclimation) determines your specific electrolyte and hydration strategies as you ramp up training.

Increasing Intensity: Improve Your Carb Timing

When training intensity is low, and you’re just riding leisurely solo miles or getting in quick easy lunch sessions, you’ll probably be fine not thinking too much about when or how much carbohydrate you’re taking in. Eating intuitively and generally feeling satisfied will do fine. That changes entirely when you start structured workouts again.

When you care about the quality of the training and you’re not just exercising to maintain a basement level of fitness or to “get slow, slower” (credit to a friend on Strava who used that as a ride title), you’ll need to do the following:

1. Eat a carb-rich, pre-workout meal, 1.5-3 hours before training—about 2 hours before training seems to be pretty optimal for most athletes. Pushing it longer than 2 hours before might be OK if you are eating an exceptionally large meal or choosing fiber- or fat-rich foods that might slow digestion. Otherwise you might risk falling blood sugar before the training session starts.
2. Fuel during training with an intra-workout carb. Gels, beverages, and easy-to-digest foods like white bread and jelly are good here. To play it safe, stick with very low-fat or non-fat, and very low- or no-fiber options. If you have ever had gut issues in training, go with beverages and target 60-140g of carbs per liter of fluid consumed, ideally using at least a 2:1 mix of glucose to fructose, but 1:1 is probably better.
3. Recover post-workout with a high-carb, lower-fat, lower-fiber meal. Rate of glycogen loss during training is increased with higher intensities and will be even further increased because you may be less fit right now or less accustomed to higher-intensity training. This will have you relying more on carbs for fuel during training than you otherwise would.

One important note: Increasing intensity of training does not guarantee that you will be burning more calories than when you were doing lower intensity work, unless you are matching or increasing session length as well. In fact, even if you do match session length, you might burn fewer calories the rest of the day because of increased fatigue and decreased non-exercise activity thermogenesis. ie. When you are tired, you move less!

Increasing Volume: Eat More (Carbs)

Whatever your weight gain, loss, or maintenance before, as you increase training you are probably going to need to be eating more. There are two primary reasons to make most of that additional eating come from carbs.

1. Glycogen depletion prevention. Since you’re less fit than you were last time you trained long hours, you’ll be burning more carbs per hour of training, even for longer and slower efforts, so glycogen depletion over the course of a training phase is imminent if not restocked aggressively. Consuming sufficient carbs daily to account for 100% of calories burned in training is a safe minimum bet. In many cases, more than that is advisable.
2. Intra-workout fueling for training quality. When sessions go longer than 90 minutes, the evidence is abundantly clear that performance in that session and in future sessions will be enhanced if carb consumption during training exceeds 60g/hr. For most sessions, when seeking optimal performance, targeting 75-140g carbs per hour is ideal. Once the gut is trained to handle it through high-carb fueling practices during training, 90-150g per hour is probably ideal.

Increasing Volume & Intensity: Protein Prevents Muscle Loss

More intense training and more of it both increase the need for protein for muscle retention due to increased cellular signaling that might cause muscle loss.  

When you do endurance exercise, there are cascades of muscle cell signals in response to the stress put on them. These signals call for “energy liberation” at all costs and for the muscle cells to become more efficient.  

Energy liberation just means that your cells are calling for anything and everything to be broken down and burned as fuel for the activity, including the very structures that make them up.

More efficient generally means slightly smaller, more capillary-dense, and slightly less heavy—i.e. muscle loss.  

The best way to combat muscle loss as a triathlete: Consume 0.6-0.8g of protein per pound of lean body mass, daily. If interested in body composition improvement, not just endurance performance, 0.8-1.0g of protein per pound of lean body mass, per day, is a good idea. 

Is Dietary Fat Important As Training Increases?

The simple answer here is: No. You do not need to concern yourself with increasing your fat consumption in response to ramped up training. Humans have plenty of fat stores throughout their body and various mechanisms to access those for energy whenever needed, so increasing fat consumption is completely unnecessary in response to increased training.  

The most common reason folks over-consume fat during their higher intensity and higher volume training phases? Under-fueling with carbs during training causing hypoglycemia, which is a powerful stimulant of hunger. And fats taste great when you feel like you are starving!

Sweat Physiology: Your Hydration and Electrolyte Strategy

The fitter you are, the more diluted your sweat is. The more heat acclimatized you are, the more diluted your sweat is. The way you heat acclimatize is by training long and hard in the heat and sweating a lot. If that has not been you recently, then you probably have higher sodium concentration in your sweat than when you last trained harder or were last training in hot weather.  Further, you will probably generate more heat and sweat more for the same level of activity as you did back whenever you trained harder.

What this means: You are going to lose fluid faster and sodium a lot faster than you might expect for a given workout intensity or outside temperature. Compounding that, if the shelter-in-place or other training restrictions caused you less exposure to the outside temperatures as it got hotter and now you’re in the dead of summer with little heat acclimatization, both of those factors are further increased.

The keys to preventing dehydration and hyponatremia when ramping up training, especially if doing so in the heat, and most especially if heat acclimatization might be lacking:

1. Always consume electrolytes with your fluid: 500-1800mg sodium per liter is good. Use sodium citrate if doing more than 1000mg per liter or if gut issues present.
2. Target 800-1200mL fluid per hour. See number 1! Never in absence of sodium.
3. Start your fueling/hydration plan within the first 5 minutes of exercise and consume every 5-10 minutes to maximize fluid absorption.
4. Enter training well-hydrated. If sweating heavily during training, this may mean consuming electrolyte beverage outside of training, and not just water.

What You Need to Do When Training More

In summary, when you ramp up training or get started again after some time off, you will likely benefit from:

1. Increased carbs and better carb timing around and during training, with 60-140g/hr during training.
2. More calories in general, primarily from increased carbs, especially during training.
3. Steady protein consumption around the clock.
4. Do not target increased fat consumption. Fuel with carbs.
5. Start hydrating with electrolyte and carb beverages in first 5 minutes and add more sodium than usual.

Dr. Alex Harrison, a certified USA Triathlon coach, holds a PhD in Sport Physiology and Performance. He is the author of The RP Diet for Endurance, creator of the RP Endurance Macro Calculator, and has authored and contributed to dozens of articles. When he isn’t pumping out training and nutrition plans in his RV-garage-turned-mobile-office, he can be found on his bike, clinging for dear life to his wife’s wheel.