How to prepare energetically for a marathon – complete guide

How to prepare yourself energetically the week before a marathon

42 kilometers and 195 meters – the classic distance from the ancient Olympic Games. A marathon is not impossible, but it requires both physical and mental endurance. In the last week before the race, the actual training is mostly done. This is when your energy plan and nutrition strategy can make the biggest difference to how you perform on race day.

Here is a clear guide to how to prepare your body for the best chance of a fast, stable and strong marathon.

The last week – energy reserves must be maximized

When you're putting your body through several hours of work, it's crucial to have enough glycogen , the body's stored carbohydrates. These are stored in the muscles and liver and are the primary source of energy during marathon running.

Fatty acids are not enough here – the intensity is too high. That's why we focus on carbohydrate loading .

Carbohydrate loading – how to do it right?

In the past, many people used a method where they first depleted the body of carbohydrates and then heavily loaded it (“carb depletion and loading”). Today we know that this has several disadvantages:

Too little energy at the beginning of the week → poorer quality in the last few sessions

Unnecessarily stressful for the stomach

Risk of fatigue and feelings of weakness

The modern method: smart & even carbohydrate loading

During the week before the race, do the following:

✔ Reduce the amount of exercise

The body needs rest to replenish glycogen in the muscles.

✔ Eat the same amount of carbohydrates as during your heaviest training weeks

Because you train less, an energy surplus is automatically created → effective glycogen loading without overeating.

✔ Benchmark:

5–7 grams of carbohydrates per kilogram of body weight per day
If you train hard even in the last week → aim for the upper part of the range.

✔ Important immediately after the workout

Quickly consume carbohydrates + amino acids within 30 minutes. This provides maximum recovery.

Protein in the last week

Protein is just as important as carbohydrates – but the amount does not need to be increased.

✔ Maintain your normal protein intake

✔ Early in the week: feel free to include fattier fish (e.g. mackerel, salmon)

✔ Last few days: choose lighter proteins like chicken or turkey

✔ Amino acids can replace part of the protein if the stomach is sensitive

The day before the race

The second most important day after the competition day itself.

✔ Rest or very light activity

✔ Continue with 5–7 g carbohydrates per kg of body weight

✔ Don't eat any new foods!

This is not the time to experiment – continue with the carbohydrates your body is used to.

Race day breakfast

Breakfast is crucial – but it should always be tested in training .

✔ Eat what you usually eat before long workouts

✔ No new foods or untested routines

✔ Feel free to supplement with a pre-race snack 45–60 minutes before the start

Example: long-release technical carbohydrates (e.g. isomaltulose-based products).

Hydration – as important as carbohydrates

Becoming dehydrated affects performance enormously.

✔ Start the race well-hydrated

✔ Increase water intake the days before

✔ Add electrolytes : sodium, chloride, potassium

✔ Drink an isotonic drink in the morning before starting

It provides both fluid and easily available carbohydrates without feeling heavy.

Energy plan during the race

The standard recommendation: ≈30 g of carbohydrates per hour , i.e.:

✔ 1 energy gel every 40 minutes

This works for:

Fast runners (~3 hours)

Exercisers (4 hours+) – you will need more gels overall because you are out longer

Always test your plan during training!

After the race – immediate recovery

A marathon puts a strain on the entire body. The first 30 minutes are crucial:

✔ 1–1.5 g of fast carbohydrates per kg of body weight

✔ 20–30 g of high-quality protein

A combination of maltodextrin + whey protein (as in Enervit Recovery Drink) kickstarts recovery perfectly.

Summary

Carbohydrate loading for one week: 5–7 g/kg/day

Protein: normal amount, lighter protein in the last few days

Breakfast: nothing new – do what you’ve tried before

Hydration: water + electrolytes before starting

During the race: ~30 g carbohydrates/h (1 gel every 40 minutes)

After the race: fast carbohydrates + quality protein within 30 min

Ready-made marathon packages – choose your energy system

Here you will find ready-made, well-balanced energy kits from leading brands: