How to Use Energy Gels Effectively in Marathon Training

How to Use Energy Gels for Running and Marathons

For marathon running, take your first energy gel approximately 30–45 minutes after starting, then continue fuelling at regular intervals. Most runners should aim for approximately 120–180 calories per hour, adjusted for body size, pace, conditions and tolerance. Do not wait until you feel tired—by then, you are already falling behind with your fuelling.

Energy gels provide a convenient source of carbohydrates during long runs and races. The key is to use the correct amount, take them consistently and practise your entire fuelling strategy during training.

How Often Should You Take Energy Gels During a Marathon?

A practical starting point is one energy gel every 30–45 minutes, depending on the calories contained in the gel and your overall fuelling plan.

Your hourly intake may also include calories from sports drinks or other fuel, so calculate the combined total rather than treating each product separately.

Hammer Nutrition recommends approximately:

• 120–140 calories per hour for lighter athletes
• 140–160 calories per hour for most athletes
• Up to approximately 180 calories per hour for larger athletes

These are starting guidelines, not a competition to consume as much as possible. More fuel is not automatically better.

When Should You Take Your First Energy Gel?

Take your first gel approximately 30–45 minutes into your run and continue at planned intervals.

If you have eaten a suitable pre-run meal, you generally do not need to take a gel long before starting. For an early race or when your last meal was several hours earlier, a gel shortly before the start may be useful—but test this during training first.

The important point is to fuel before your energy begins to drop. Do not wait until you feel hungry, weak or exhausted.

How Many Calories per Hour Do Runners Need?

Most endurance athletes perform well on approximately 120–180 calories per hour during prolonged exercise. Runners may require less than cyclists because running places more physical stress on the digestive system.

Your ideal intake depends on:

• Body weight
• Running pace and intensity
• Race duration
• Temperature and humidity
• Personal digestive tolerance
• Calories obtained from drinks or other fuels

Start conservatively and adjust during long training runs. The correct amount is the lowest intake that provides consistent energy without causing hunger, weakness or stomach discomfort.

Should You Take Energy Gels with Water?

Yes. Energy gels should generally be taken with a few mouthfuls of plain water to support swallowing, digestion and absorption.

Avoid washing a concentrated gel down with a high-calorie sports drink. Combining both at the same time can create an overly concentrated mixture in the stomach, increasing the risk of bloating, nausea or digestive discomfort.

Drink according to the weather, your size and your personal sweat rate. Avoid forcing excessive amounts of fluid simply because you are following a rigid schedule.

Can Taking Too Many Energy Gels Cause Stomach Problems?

Yes. Consuming more calories than your body can process is a common cause of nausea, bloating and stomach distress during marathons.

Problems can also occur when runners:

• Take several gels too close together
• Combine gels with a high-calorie sports drink
• Take gels without enough water
• Use unfamiliar products on race day
• Consume more fuel than they practised with
• Choose very sweet gels that become difficult to tolerate over several hours

More calories do not guarantee more energy. Your digestive system has a practical limit, especially while running.

How Should You Practise Race-Day Fuelling?

Use your long training runs as a full rehearsal for race day.

Practise:

• The same breakfast you plan to eat before the marathon
• The timing of your first gel
• Your planned gel interval
• Drinking water with each gel
• Carrying and opening gels while running
• Any electrolyte products included in your plan
• The flavours you intend to use during the race

Change only one element at a time. This makes it easier to identify what works and what causes problems.

Never introduce a new gel, drink or fuelling schedule on race day. The marathon is the final examination, not the revision session.

How Many Energy Gels Will You Need for a Marathon?

The number depends on your predicted finishing time and gel interval.

For example:

• 3-hour marathon: approximately 4–6 gels
• 4-hour marathon: approximately 6–8 gels
• 5-hour marathon: approximately 8–10 gels

These are only examples. Your total must account for the calories in each gel and any additional fuel consumed during the race.

Carry at least one spare gel in case you drop one, miss a planned feed or the race takes longer than expected.

Choosing an Energy Gel for Running

Choose a gel that is easy to consume, provides predictable energy and agrees with your stomach during prolonged running.

Hammer Gel uses complex carbohydrates with no added refined simple sugars, helping provide smooth, consistent energy without an overly sweet taste. It is available in multiple flavours, including caffeinated and non-caffeinated options.

If you are unsure which flavour suits you, the Hammer Gel Sampler Kit allows you to test different options during training before committing to your race-day choice.

Compare individual sachets, the 12-flavour sampler and the bulk jug in our Energy Gels collection, or read the Hammer Gel Fuelling Guide for detailed advice on timing, quantities, water and race-day planning.

Should You Use Caffeinated Energy Gels?

Caffeine can be useful during prolonged exercise, but it should be used deliberately rather than included in every gel automatically.

A sensible approach is to begin with non-caffeinated gels and reserve caffeine for the later stages of the marathon, when mental and physical fatigue becomes more noticeable.

Always check the caffeine content and practise your strategy during training. Avoid combining several caffeinated gels with large amounts of coffee or other caffeine sources.

Energy Gels Are Only One Part of Marathon Nutrition

A complete marathon strategy should cover:

• Your pre-race meal
• Carbohydrate intake during the race
• Water and fluid intake
• Electrolyte replacement
• Post-race carbohydrates and protein

Visit our Marathon Nutrition collection for energy gels, endurance fuel and electrolytes, or read our Running Fuelling Guide for help planning what to use before, during and after your run.

The Bottom Line

Take your first energy gel approximately 30–45 minutes into your marathon and continue at planned intervals. Aim for a total of around 120–180 calories per hour, take gels with water and practise the complete strategy during training.

Fuel consistently, not reactively. A well-rehearsed plan will always beat grabbing random gels after your energy has already disappeared.