Race-day fueling for the London Marathon should match your carbohydrate target, hydration needs, and stomach tolerance rather than whichever product is handed to you first. Gels suit runners who want a compact dose, chews suit smaller repeated portions, and sports drinks can be a good fit when fluid and carbohydrate need to arrive together.
For a marathon lasting several hours, aim for 30 to 90 grams of carbohydrate per hour. Choose the lower or higher end according to your pace, duration, training, and gut tolerance. An effort lasting less than about 60 to 75 minutes usually does not need a gel or chew during the race.
The London course can supply part of your plan, but it cannot replace one. The first six miles have no official on-course carbohydrate source, so take early fuel before the start or carry it with you.
Key takeaways
- London Marathon runners can use Lucozade Sport at Miles 7, 15, 21, and 23, with gels available at Miles 14 and 19.
- When you combine gels with sports drink, add their carbohydrate and fluid together instead of counting each product separately.
- Concentrated gels may need plain water, so follow the label; many isotonic gels are made for use without extra water.
- For a long race, take your first carbohydrate portion about 30 to 45 minutes after the start, then practice the exact plan on long training runs.
Fuel Targets for a London Marathon
Your pace changes the job your fuel has to do. A fast marathoner may finish before carbohydrate intake becomes necessary, while a runner expecting four, five, or six hours has more time to use stored carbohydrate and fluid. Taking carbohydrate products when you do not need them may add stomach trouble without solving a performance problem.
Use 30 grams per hour as a practical starting point if you have not trained with race fuel. Runners who tolerate more can work toward the top of the target, but that level belongs in a trained plan rather than a last-minute race-day experiment. Count carbohydrate from drinks, gels, chews, and any pre-race fuel together.
Set the target before choosing the product:
- Choose the lower end if your pace is easy, your race is shorter, or your stomach is sensitive.
- Choose a higher intake only after practicing it on long runs.
- Count carbohydrate from every source, including drinks, gels, chews, and pre-race fuel.
Your product choice should make the hourly target manageable. It should not force you to swallow more liquid, chew more pieces, or take a stronger mixture than your stomach can handle.
Choosing Between Gels, Chews, and Drinks
Gels, chews, and sports drinks deliver fuel in different ways.
| Option | Delivery format | Carbohydrate role | Hydration contribution | Practical limitation |
|---|---|---|---|---|
| Gel | Compact packet | Low-fiber carbohydrate dose | Little or none | Concentrated gels need water |
| Chews | Individual pieces | Divided carbohydrate portions | Little or none | Chewing takes time |
| Sports drink | Liquid serving | Carbohydrate in a drink | Fluid and electrolytes | Higher targets require more volume |
Gels for Compact Fuel
A gel can be a simple choice when you need a large carbohydrate dose without carrying much liquid. It contains little fiber and takes only a few seconds to swallow, which helps when you are running hard or carrying several hours of fuel in a small belt.
Concentrated gels may need plain water, so follow the label. If the label calls for water, take about 3 to 5 fluid ounces with the gel; swallowing it dry can leave a thick mixture in your stomach and cause cramps. Many isotonic gels are formulated for use without additional water, but products differ.
Read the label before race morning. Check the carbohydrate amount, whether it contains caffeine, and whether it uses glucose or maltodextrin together with fructose. A runner targeting a higher intake may tolerate a blend better than a glucose-only product.
Chews for Smaller Portions
Chews work well when one large dose feels unpleasant. You can take one piece, wait, and take another later, giving you more control over the pace of intake. Depending on the carbohydrate in each piece, reaching 60 to 90 grams per hour may require roughly 6 to 9 pieces per hour.
Chewing and swallowing that amount while running can become uncomfortable, especially during a crowded section of the course or late in the race. Chews suit runners who dislike gels, prefer a firmer texture, or want to split a dose into small portions.
A hand reaching for fruit chew candies in a wooden bowl.
Open the packet before the start or carry it where you can reach it without stopping. Wrestling with packaging at mile 18 is a poor time to discover that the pieces are difficult to remove.
Sports Drinks for Fluid and Fuel
A sports drink can be a good fit when you need carbohydrate, fluid, and electrolytes together. Plain water typically provides little or no carbohydrate and few electrolytes, so it cannot cover the same job by itself.
Official Lucozade Sport and gel locations by London Marathon mile
Lucozade Sport contains about 32 grams of carbohydrate and 250 milligrams of sodium in a 17-fluid-ounce serving. Getting 60 to 90 grams per hour from that drink alone would require roughly 34 to 47 fluid ounces per hour, which may be more liquid than you can comfortably drink.
A drink can therefore handle the fluid part of a mixed plan while a gel supplies compact carbohydrate. Count the drink’s carbohydrate before adding another product, rather than treating each source as a separate allowance.
Athlete drinking water while running in a marathon.
Combining Fuel Without Stomach Trouble
Mixed fueling can go wrong when each product is counted separately. Two gels and several cups of sports drink may push the total carbohydrate concentration too high for the amount of fluid reaching the stomach.
Write down the carbohydrate in each planned serving and add it by hour. Match that total to the fluid you expect to drink. If the mixture feels heavy, take more water, use less carbohydrate at one point, or leave a longer gap between products.
Products containing glucose or maltodextrin with fructose may support higher intakes than glucose alone. Ratios such as 1:0.8 or 2:1 glucose to fructose are used in products aimed at higher hourly totals, but test a blend before race day.
Small details can also upset a sensitive stomach:
- A concentrated gel taken without enough water
- A strong drink combined with several gels
- A new flavor that becomes sickening after two hours
- Chews with a texture that is hard to swallow while running
- Caffeine that feels fine in training but causes urgency on race day
Change one thing at a time during long runs. If a product causes trouble, record the amount, the fluid taken with it, and the timing. This helps you work out whether the problem came from the product or from the concentration in your stomach. For a broader comparison of liquid and solid fuel, drinks and gels differ in how they deliver carbohydrate, so treat them as parts of one plan rather than separate allowances.
London Marathon Stations and the Early Gap
The London Marathon provides Lucozade Sport at Miles 7, 15, 21, and 23, with Lucozade Sport Gels at Miles 14 and 19. The first six miles have no official on-course carbohydrate source, so take fuel before the start or carry it if you want to eat earlier.
Aid-station pours vary, and a crowded station may slow you down or make it difficult to drink the amount you intended. Do not assume that every cup replaces a full serving. Carry enough personal fuel to cover the gaps and the possibility that you miss a handoff.
Marathon runner receiving water from a volunteer on a sunny course.
You have two workable approaches:
- Use the course drink and gels as planned, while carrying early fuel and a backup serving.
- Carry your full personal plan and use course drinks only when they fit your fluid and carbohydrate totals.
If you use official products, practice with the same type before race day. If you do not want to depend on them, carry products you have already tested and treat the stations as optional support.
Timing and Practice for Race Day
Start fueling before fatigue appears. For a long race, take the first gel or carbohydrate portion about 30 to 45 minutes after the start, then space later portions through the race instead of waiting for the first sign of weakness.
Set reminders by time, mile, or both. Taking fuel only when you feel empty leaves little time to chew, swallow, or find water before the next portion is due. Start chews early enough to finish each portion before the next one, and use sports drink steadily when fluid and carbohydrate are both part of the plan.
Practice the exact products and quantities on long training runs. Test flavor, texture, concentration, and caffeine, because each can change how your stomach responds after several hours. Open packets with the hand you will use on race day, and rehearse taking fuel near the end of a run when tired legs make small tasks harder.
Write the final plan on your race notes in time order. Mark what you carry, what you take before the start, what you take with water, and what you may collect from the course. Then run that plan at least once before London.
A Clearer Race-Day Plan
Choosing Between Gels, Chews, and Sports Drinks for London Race-Day Fueling works best when your plan accounts for what London actually provides on the course. Mark the Lucozade Sport stations at Miles 7, 15, 21, and 23 on your race map, then place your personal fuel around them.
Frequently Asked Questions
Should I choose water or sports drink during the marathon?
Plain water is the better choice when gels or chews already provide enough carbohydrate and electrolytes. A sports drink can be a good fit when you want fluid and additional carbohydrate from the same source. Count both the drink and your solid fuel before deciding how much of each to take.
Can I take an isotonic gel without water?
Many isotonic gels are formulated for use without additional water, but that is not true of every product. Check the specific gel before race day and practice it during training. A gel that is not designed for this use may still need water to go down comfortably.
I am Ozan, a London-focused running writer and marathon enthusiast with a passion for helping people discover the city’s best races, running routes, walking trails, and fitness events. I research and write practical, up-to-date guides covering marathons, race preparation, training tips, running gear, and everything related to staying active in London.
My goal is to create reliable, easy-to-follow content that helps runners and walkers of all experience levels explore London with confidence, whether they’re preparing for their first 5K or their next marathon.
