What to eat before and during a half marathon?

In a half marathon (or other races lasting 1–3 hours) nutrition can play an important role. It helps to have a nutrition plan and to be prepared for the race. Many runners experience problems in a half marathon that are related to nutrition – and that can easily be prevented.

In this article we will briefly go through carbohydrate loading (carb-loading) and breakfast, then move on to the nutrition basics, general rules and the most common mistakes.

Carb-loading

Carb-loading is a technique aimed at maximising your carbohydrate stores before a race. For a half marathon, however, extreme overeating of carbohydrates is not needed. What matters is to come to the start line with full, not depleted glycogen stores, which you can achieve with a normal carbohydrate intake. An evening meal with pasta, rice or potatoes the day before the race is more than enough.
It is not about the amount – the goal is to get to the start with enough energy, but feeling light.

Breakfast

Breakfast is probably the most important part of nutritional preparation for a half marathon. Ideally it should be eaten 3–4 hours before the start, contain at least 100 g of carbohydrates and have a low fibre content (mainly for runners with a sensitive digestion).
Suitable options are e.g. white bread with jam, bagels, low-fibre cereals, and if you have no digestive problems, also porridge or muesli.
The aim of breakfast is to top up liver glycogen, which helps to keep your blood sugar level stable during the race.

Ideally it is a good idea to top up liver glycogen 15-30 minutes before the start, for example with a hyve Endurance pro drink.

The most common nutrition problems during a half marathon

• Energy stores ran out
  Symptoms: “hitting the wall”, not being able to hold your pace in the closing stages of the race.

• Gradual dehydration
  Typically a problem in races in the heat. Gradual fluid losses can significantly reduce performance.

• Digestive problems
  E.g. stomach cramps, bloating – often caused by an excessive intake of sports nutrition while running.

Topping up energy

The main source of energy is carbohydrate, especially if you plan to run under 2 hours.
The body naturally stores about 500-800 g of carbohydrates in the muscles and 80 g in the liver, which in theory is enough for a half marathon.

To be on the safe side it is recommended to take in 30–60 g of carbohydrates per hour in the form of a gel, bar, sweets or drink. With solid foods, watch out for a low content of fat, protein and fibre.

Faster runners often choose the liquid form, because at higher intensity it is hard to chew.

How much is 30 g of carbohydrates?

It roughly corresponds to one of the following options per hour of racing:

• 1 gel + a little sports drink

• 0.5–1 bottle of sports drink (750 ml)

• 1 energy bar

For exact amounts, check the labels of the products you use.

Hydration

Especially in hot weather, dehydration can be a key factor affecting performance.
The advice to “drink to thirst” works for most runners. Even so, some people want to be more precise and track how much fluid they lose through sweat while running, and adjust their fluid intake plan accordingly.

The goal is to prevent losing more than 2 % of body weight through sweat.

• A light “sweater” often barely needs to drink at all.

• A heavy “sweater” does need a plan.

Do not drink excessively! Gaining weight during a race is a sign of drinking too much and there is a risk of hyponatraemia.

Good hydration starts several days before the race.

Digestive problems

20–50 % of runners have some kind of digestive problem in a half marathon.
Some are minor, others serious enough to affect performance. There can be several causes:

• A high intake of fibre or fat

• Carbohydrate drinks that are too concentrated

• Race nerves (race-day anxiety)

• Individual susceptibility

The most common mistakes on race day

1. Sticking to the plan at all costs
   If nausea or other problems appear, let the plan go – be flexible.

2. Trying new products on race day
   New products bought at the expo are a common disaster. Use only what you have tested.

3. The “more is better” approach
   More food or more fluid does not automatically mean better performance – you can even harm yourself with it.

A few closing notes

• Losses of sodium and other minerals are not a problem for most runners in a half marathon, supplementation is not necessary – and it may even make digestion worse.

• Caffeine (3 mg - 6 mg per kilogram of body weight) can help, but it depends on individual tolerance.

• Test everything in training! Ideally start with your nutrition plan 8–10 weeks before the race.

For a broader understanding of nutrition strategy you can also read the article: What to eat before a marathon: what science says and how to use it in practice?