In the simplest terms, pre-workout nutrition describes your starting point and what you bring into the session. How recently have you eaten? What did you eat? How much?
Intra-workout nutrition looks at how well that fuel sustains your session. Do you have nutrition available for the duration of your session? And if you add fuel mid-session, what’s ideal?
Note: This is the second article in our workout nutrition series. Much of what we covered about pre-workout nutrition also applies here. Many of the same ideas about substrate availability and performance still matter once training begins, but there are a few distinctions that make sense to separate.
The purpose of intra-workout nutrition
During training, your muscles rely on stored glycogen and circulating glucose to keep producing ATP. Glycogen is stored in several regions within muscle fibers, and different stores are used depending on the type and duration of training. As training intensity increases, your body relies more heavily on carbohydrates, and glycogen becomes your main fuel source. When glycogen levels get low, performance can drop, and your body may begin using more amino acids for energy, which you want to minimize if you’re trying to maintain or build muscle. One way to reduce protein use, including the breakdown of muscle tissue, is to ensure adequate fuel during training sessions.
The type of training you’re doing also shapes how important your workout nutrition is. For example, lower-volume strength training doesn’t usually depend much on carbohydrate availability, whereas endurance or higher-intensity interval training sessions benefit more from carbohydrates during training.
Before we dive into specifics, we need to look at the considerations that apply to intra-workout nutrition.
| Consideration and questions for determining if your training demands specific intra-workout nutrition | ||
|---|---|---|
| Consideration | Description | Practical takeaway |
| Overall energy intake | Are you in an ongoing Calorie deficit or following a diet that depletes glycogen? | The lower your glycogen stores, the more important intra-workout carbohydrate intake becomes. |
| Time since last meal | How long has it been since your last meal or carbohydrate intake? | If it’s been several hours, an intra-workout carb source can help maintain blood glucose and performance. |
| Type, intensity, and duration of activity | Are you doing strength, power, or endurance work? High or low volume? Engaging in repeated glycogen-depleting rounds? Is the environment hot? | Longer or higher-volume, higher-intensity sessions benefit more from intra-workout carbs than shorter, low-volume sessions. Additionally, hot environments may require more hydration consideration. |
| Psychology and satiation | How full or comfortable do you feel going into your training session? Are you easily affected by perceived hunger or weakness from lack of eating? | Fueling during training can relieve feelings of sluggishness or shakiness and improve focus. |
| Age, recovery, or injury status | Are you over 50, managing an injury, or dealing with slower recovery between sessions? | Older adults and those in recovery may benefit from including protein and carbohydrates during training to support muscle and reduce breakdown. |
Many of the factors that determine whether you need fuel before training are ones that determine whether you’ll benefit from consuming anything during training. This helps frame intra-workout nutrition as more relevant when your pre-workout meal can’t sustain the full duration or intensity of your training session.
So, the need for intra-workout nutrition usually boils down to these three conditions:
• Longer durations that increase glycogen turnover.
• Repeated high efforts that rely more on glycogen availability.
• Hydration loss or a continued energy deficit.
With that in mind, let’s look at how different training styles, hydration, and even low energy availability can influence your nutrition decisions.
Endurance
A systematic review and meta-analysis from Ramos-Campo et al examined more than 130 studies in endurance trainees and found that the longer the session, the larger the benefit of taking in carbohydrates during exercise. In events under 60 minutes, they didn’t really lead to a meaningful effect. However, once the sessions passed the one-hour mark, performance improvements became more noticeable, and by the 120 to 180 minute range, the effects were even larger. So, duration was one of the strongest factors in the results.
Overall, this lines up with what we see in pre-workout nutrition: the longer you go, the more important it becomes to keep your carbohydrate availability up. Once your training extends past an hour, mid-session fueling also becomes easier to justify.
What about adding in protein?
A systematic review and meta analysis from Nielsen et al looked at how adding protein to carbohydrate feedings affects endurance performance. The authors grouped studies into a few categories, including feedings during exercise, feedings during the recovery window between two bouts (note: not the same as post-workout nutrition), and they also made a point to match total Calories.
The review looked at a range of training times (1 to 3 hours) to see how glycogen turnover or nutrition could be a limiting factor. And in this context, it’s clear that having some protein intake during these longer sessions supports performance and overall output. So, to be clear, intra-workout nutrition helped performance.
That said, a secondary question becomes, “Did adding protein to a carbohydrate supplement improve performance compared to carbohydrate alone?”
While performance did improve during long sessions, when the comparisons are calibrated for total Calorie intake, the differences were less stark. This means the benefit is likely to be driven by the extra Calories, not necessarily just the protein itself.
Beyond performance, another factor to consider regarding protein is if intra-workout strategies are helpful in reducing (downstream) muscle damage. A double-blind crossover trial from Liang et al tested different carbohydrate and protein combinations before and during a longer running session. Note, it wasn’t a pure intra-workout design, but the feeding happened close enough to highlight if different strategies could affect performance and muscle damage.
Result? Performance didn’t differ, but protein conditions the next day showed lower levels of creatine kinase and myoglobin. Now, to be clear, these are indirect markers and not definitive evidence of reduced muscle damage, and the study was small, with only 10 participants. Still, it’s an interesting point that we’ll revisit more when discussing post-workout nutrition.
Quick recap: Unsurprisingly, your carbohydrates continue to be the driver of performance during longer or more demanding sessions, but total Calorie intake is still an important factor. Your protein isn’t going to move the needle on performance the way carbohydrates do, but having some in the mix during long endurance work may reduce the rise in muscle-damage markers afterward.
Resistance training
Just as I discussed in the pre-workout article, there isn’t a lot of strong evidence to support specific nutrient timing during resistance training sessions under 60 minutes. Also, MacroFactor has discussed protein timing and distribution in detail, so this is really about taking a closer look at carbohydrates.
In our pre-workout article, we looked at the systematic review and meta-analysis from King et al that examined 21 studies with more than 260 participants consuming a carbohydrate drink, placebo, or water before or during their workout.
The results were mixed, with relatively small benefits that only showed up when resistance training sessions lasted longer than 45 minutes or began after at least 8 hours of fasting. The challenge of the training sessions also mattered. For example, the closer participants trained to failure, the more useful carbohydrates became. Though the amount of carbohydrates consumed didn’t make much difference.
What can be confusing when looking at resistance training and intra-workout nutrition research is that the mechanistic and outcome data don’t always perfectly align. For example, a review by Bird et al hints at the need for carbohydrate and protein availability during resistance exercise so it can help with glycogen resynthesis or hormone markers. And while these mechanism arguments make a good case for maintaining carbohydrate availability during training, they don’t always translate into measured performance shifts (like those summarized by King et al).
One likely reason for this disconnect is understanding energetic demand. When you’re lifting something heavy, stored phosphocreatine can supply some of that immediate energy while anaerobic glycolysis will contribute more the longer you continue. So, as training increases and your rest periods shorten, or if you’re training closer and closer to failure, carbohydrate metabolism will become more important. Training style and duration determine how much glycogen you will use.
So a 45-minute lifting session at a moderate intensity with longer rest periods won’t challenge glycogen stores the same way an intense, 2-hour resistance workout that’s cycling intensity would.
Quick take-home: For shorter or lower-volume lifting sessions, extra carbohydrates during training probably don’t add much. But if sessions get longer or are highly intensive throughout, maintaining carbohydrate intake could make a small difference.
When hydration or continued low energy status could be a factor
I haven’t talked much about hydration because these articles are mostly focused on macronutrient factors, but hydration still plays a supporting role in training performance.
In simple terms, hydration or euhydration refers to how well your body maintains a balance of water and electrolytes. How hydrated you are going into a workout can affect not only performance but how hard your session feels. Low energy intake can also affect your hydration. When Calories stay low for long enough, glycogen stores, total body fluid, and electrolytes can all drop from their ideal baseline.
A meta-analysis by Savoie et al looked at 28 studies on hypohydration and muscle performance and found that losing around 3% of body water reduced muscular endurance by about 8% and strength by roughly 5%, with similar drops in anaerobic power.
Later trials follow a similar pattern, showing that mild to moderate dehydration can reduce endurance and strength, though the effect size depends on training status and the method of dehydration. Some authors have also noted that research in this area is more complex than they’d prefer, given that study designs vary widely and dehydration measurement methods are inconsistent.
Still, across different approaches, a fair takeaway is that being slightly dehydrated could hurt endurance and may take a small edge off strength, but I wouldn’t get too attached to specific numbers.
With energy status, there are discussions that short-term low energy availability reduces your muscle’s ability to take up and oxidize glucose. Meaning, if you’ve been in a deficit for a period of time, your muscles may not use intra-workout carbohydrates as well. This raises a fair question: How much could low energy reduce carbohydrate use during training, and is intra-workout nutrition still worthwhile if you aren’t starting the session with full stores?
A 2025 study by Margolis et al tested this idea by placing participants in a range of deficit percentages (20, 40, or 60%) for six days. Researchers then had them complete 90 minutes of steady-state cycling, during which they consumed 80g of glucose.
They found about a 10% reduction in exogenous glucose oxidation (how well you can use what you immediately take in), while performance was the same as when participants were fully fueled. This shows that intra-workout carbohydrates can still support performance even when energy intake has been low. Meaning, it’s not wasteful to take in carbohydrates during your workout if you’re participating in endurance training.
What about higher intensity intervals or crossfit training?
A 2025 study from Triviño et al looked at CrossFit athletes completing a two-hour mixed session that included lifting and interval work. The subjects also consumed 60g of carbohydrates during the workout, and then a placebo on a separate day. There were no differences in performance or their perceived exertion. But there are two things worth noting: the athletes already used intra-workout carbohydrates in their normal training, and they entered the sessions well fed with prior carbohydrate intake.
Taking all these factors together, you could suggest that carbohydrate ingestion during training doesn’t move the needle much if you’re already in a fed state, but the Margolis study shows that it may still help when you start with some degree of depletion. And if you recall from the King et al study, intra-nutrition started showing more relevance after 8 hours of fasting in resistance training (though their pre-workout nutrition study showed less of a difference). So while it’s not definitive, there could be something there with energy restriction, depending on length and severity. This also goes back to what I was discussing regarding resistance training in general. Meaning, let’s say you’ve jumped back into lifting while also trying to lose weight, are utilizing a lower carbohydrate diet, and are also training to failure and going pretty hard for 45 to 60 minutes? This is the kind of situation where you’d give more thought to intra-workout nutrition, but I’ll admit that this isn’t directly covered in research.
Quick take-home: If carbohydrate availability is already high, you’re probably fine during shorter sessions. If energy availability stays low or hydration drops, performance could start to slip, and in those cases, intra-workout carbohydrates may become more relevant.
What about pre-workout nutrition versus intra-workout?
Direct comparisons of pre-workout meals and intra-workout carbohydrates barely exist, but that’s mostly because the question isn’t very practical. The useful question isn’t which one is “better,” but when a pre-workout meal stops being enough on its own. A solid meal before training sets you up well by topping off glycogen and keeping blood glucose steady, but in some training situations, that only carries you so far. That’s where intra-workout carbs start to matter.
A meta-analysis from Bourdas et al reviewed more than 40 years of data and found that once sessions last longer than an hour, taking in carbs during the workout provides a measurable performance benefit beyond anything you did beforehand. And to be clear, it’s not that pre-workout nutrition stops working – it’s that longer sessions create fuel demands that a single pre-workout meal just can’t sustain. So, the value of intra-workout carbs isn’t about “beating” pre-workout intake but more about extending how long you can keep output high once the session outlasts your starting fuel.
What to eat while training
Ideally, intra-workout nutrition should prioritize digestibility and ease. Start by considering gastrointestinal comfort and portability. Choose foods or drinks that are easy to consume and sit well with you during training.
Overall, glucose–fructose blends (roughly a 2:1 ratio) have decent evidence behind them for endurance training and may slightly improve total carbohydrate oxidation rates. Liquid options also make it easy to include sodium or other electrolytes, especially when training in the heat.
That said, whole-food options can work just as well when matched for total carbohydrate intake. Studies comparing foods like bananas, raisins, honey, and even potatoes against drinks or gels have shown good performance outcomes. The tradeoff tends to be comfort and practicality, as higher fiber can cause some GI distress, and whole foods items can be a bit more cumbersome.
Additionally, concentration, dose, and timing can drive comfort. A 2025 systematic review on minimizing GI symptoms found that sipping the carbohydrate fructose-glucose mixes helped with GI discomfort. I should note that research tends to put an emphasis on concentration over exact timing, but in practice, you could argue that sipping small amounts or larger intakes every 15 to 20 minutes works fine too. The authors also note that GI tolerance can be “trained,” and that absorption and comfort can improve over time.
In short, the best intra-workout nutrition is the one you can consume easily and scale with your demand.
Putting this together for intra-workout nutrition considerations
Most people don’t need an elaborate plan for fueling during a workout. But in some cases, it helps to keep your carbohydrate or fluid intake steady as you train. Keep in mind that these are flexible guidelines, not hard rules, and they assume your pre-workout meal isn’t enough to sustain you through the entire session. The time ranges are simplified for practicality, not meant as exact cutoffs.
Strength and resistance training
- In short or moderate sessions, carbohydrate intake is rarely a limiter for performance.
- For workouts lasting more than 45 minutes, or when training fasted, you can consume about 0.3-0.5g/kg of carbohydrate per hour. Most people sip gradually.
- Ideally, everyone should hit their total daily protein (1.6-2.2g/kg/day) and have a balanced diet of macronutrients.
Hypertrophy or hybrid training
- Carbohydrates may matter more if training exceeds 45 minutes.
- You can consume about 0.3-0.5g/kg of carbohydrate per hour. Most people sip gradually.
- Optional: Adding protein (0.3 g/kg) may help protect muscle.
Endurance training (>60 minutes)
- Carbohydrate availability is more likely to impact performance.
- For sessions over an hour, 0.5-1.2g/kg carbohydrate per hour (roughly 30-90g/hour). Composition-wise, a mix of glucose + fructose (2:1 ratio).
- You can sip continuously every 15-20 minutes.
- Optional: Adding protein (0.3 g/kg) may help protect muscle.
Closing
The goal of intra-workout nutrition is to support you when your pre-workout meal isn’t quite enough to sustain your workout. For the average person training under an hour, you can probably get by without any specific intra-workout nutrition, especially if you’ve eaten within the past few hours and are well hydrated. But as duration, intensity, or environmental stress increases (see: hot outside), getting even small amounts of carbohydrates, fluids, and a little protein could make a difference. While you can use nearly any food source, liquids and gels tend to be more practical since they’re easier to digest and consume during training.
Our final article will look at post-workout nutrition and finish things out.
