# How do I train and fuel for a half or full marathon?

Source: https://nume.co.in/marathon/ · Checked on 12 November 2026

A beginner marathon plan from a major race runs 16 weeks with three runs a week, and the long run grows to 18 to 20 miles (29 to 32 km) before the training eases off for race day. A beginner half plan from the same organiser runs 10 weeks. Fuel by the gram: 10 to 12 g of carbohydrate per kg a day for the 36 to 48 hours before a full, 1 to 4 g per kg in the 1 to 4 hours before the start, and 30 to 60 g an hour from the first hour, rising to as much as 90 g an hour after 2.5 to 3 hours. Drink enough that you lose no more than about 2% of your weight, and not so much that you gain any.

The rest of this page gives the numbers and where they come from. Nume plans the weeks in between: everyday food at your eating times around your runs, and strength work that keeps your legs fresh for them.

## How long to train

The TCS London Marathon beginner plan is 16 weeks with three runs a week, each run day followed by a rest day. Its longest run comes in week 13, with a distance goal of 18 to 20 miles. The Big Half beginner plan from the same organiser is 10 weeks of three sessions, with a longest run of 12 miles (about 19 km). If you can't yet run for 30 minutes, start with [your first 5k or 10k](/first-5k-10k/).

**In Nume:** bring the plan you follow, from a coach or an app, by photo, paste or a typed list. Your run days and their minutes sit on your week, marked as yours or your coach's, and Nume plans your food around them. Still choosing a race? Ask Talk for half and full marathons in a city on the dates you want, up to 120 days ahead.

## The long run

Run it at an easy pace, where you can talk in full sentences, and add to it slowly; [how fast to add distance](/first-5k-10k/) has the evidence. The long run is also where you practise race fuel: the same drink, gels or food, at the same rate you plan for race day, so nothing is new on the day.

**In Nume:** the meal before a long run is planned a little lighter, and the one after is planned larger with more protein, and each meal says why. After a run of 75 minutes or more, Today offers a snack in the hour after when your next meal is 2.5 hours or more away. Tell Talk "a bigger lunch on Sundays" and, once you tap to confirm, that meal takes a bigger share of the day on every Sunday.

## Everyday food in training

Training days need carbohydrate. The joint sports-nutrition guidance from the American College of Sports Medicine (ACSM) and the US and Canadian dietetics bodies gives 5 to 7 g per kg a day for about an hour of training a day, and 6 to 10 g per kg for one to three hours. Protein is 1.2 to 2.0 g per kg a day, with about 0.3 g per kg after key sessions and at meals through the day.

For a 65 kg runner on an hour a day, that is about 325 to 455 g of carbohydrate and 78 to 130 g of protein, with about 20 g at each meal. Rice, bread, potatoes, pasta, noodles, oats, fruit and milk carry most of the carbohydrate; eggs, chicken, fish, paneer, tofu, beans and yoghurt cover the protein. More in [protein](/protein/).

**In Nume:** your runs count. Regular runs are part of how your daily energy is worked out, and two or more sessions a week above light effort put your protein at the training range, about 1.6 g per kg. Choose "Perform better" and Nume plans food to train and recover on, around what you use; see [choosing a goal](/choose-a-goal/).

## Carb loading and race morning

For a race of over 90 minutes, the ACSM guidance is 10 to 12 g of carbohydrate per kg a day for the 36 to 48 hours before. At 70 kg that is 700 to 840 g a day, much more than most people eat, so choose foods low in fibre that are easy to eat in quantity: white rice, noodles, white bread, bagels, potatoes without the skin, pasta, rice cakes, juice and sports drinks. A half that takes you over 90 minutes follows the same guidance; for a shorter race, 7 to 12 g per kg on the day before is the guide.

On race morning, eat 1 to 4 g per kg in the 1 to 4 hours before the start, from foods you've already tried before long runs, low in fat and fibre: toast with jam, rice porridge, a bagel with banana, oats. If you use caffeine, the International Society of Sports Nutrition (ISSN) finds 3 to 6 mg per kg, usually about an hour before, improves endurance; 9 mg per kg brings more side effects and doesn't seem to be needed. At 70 kg, 3 to 6 mg per kg is 210 to 420 mg.

## Fuel during the race

The guidance is 30 to 60 g of carbohydrate an hour for 1 to 2.5 hours of running, and up to 90 g an hour beyond 2.5 to 3 hours, where mixes of glucose and fructose are used best. A half mostly sits in the first band; a first marathon, which takes most people well over three hours, sits in the second.

What 30 to 60 g looks like: one or two gels, a banana and a few sips of sports drink, or a handful of jelly sweets. Practise the amount on long runs, because the gut adapts to it.

## Drinking without overdrinking

Keep fluid losses under about 2% of body weight; past that, endurance drops, most in the heat. Drinking far more than you lose is the other risk. In a study of 488 runners at the 2002 Boston Marathon, 13% finished with low blood sodium, and gaining weight during the race was its main risk factor, along with finishing times over four hours.

To learn your own need, weigh yourself before and after a long run in race-day weather. A loss over 2% means drink more next time; a gain means drink less. Afterwards, drink 1.25 to 1.5 L for each kg lost.

**In Nume:** on a run of 90 minutes or more, the note before the run adds "On a long, hot session an electrolyte drink can help." Ask Talk the temperature, humidity and chance of rain at the start on race morning, up to 10 days ahead.

## The taper

A review of tapering studies found the best gains from a taper of about two weeks, with training volume cut by 41 to 60% and the pace of your hard sessions kept the same. Keep running; just run less.

**In Nume:** put race weekend on Week as an all-day event and, if a Nume workout is planned that day, Nume asks "Training on Sat?" with Keep, Make it light or Rest, so its workout fits the race.

## Strength through the training block

A review of randomised trials found strength training cut sports injuries to under a third. One or two short sessions a week keep the legs, hips and trunk strong for the later miles: split squats, calf raises, Romanian deadlifts, planks.

**In Nume:** on the day of a run and the day before, leg work in Nume's workout uses only bodyweight or bands, so a strength session never takes the edge off a run. Tell Talk "more calves and hips for running" and Nume keeps it for the workouts it writes next. Log a run and Today says "Today's workout keeps leg work light."

## Train for it with Nume

Bring your plan or put your run days on Week. Nume plans every day's meals at your eating times around them, lighter before and larger after, writes strength work that keeps your legs for running, and plans race weekend when it comes.

## Common questions

### How many gels for a marathon?

Multiply your target by your hours. At 60 g an hour for four hours, that is 240 g: about ten gels if each has 25 g. Check the pack, and count sports drink and food toward it.

### Should I run the full distance before race day?

The London beginner plan doesn't: its longest run is 18 to 20 miles.

### Can I lose weight while training for a marathon?

Yes, slowly, with enough carbohydrate on long-run days. See [why the scale has stopped moving](/not-losing-weight/), and [exact or approximate](/exact-or-approximate/) on watch calorie figures.

### What should I eat after a marathon?

Carbohydrate and about 0.3 g of protein per kg at your next eating time, and 1.25 to 1.5 L of fluid for each kg lost.

## Sources

- [Thomas, Erdman and Burke, Position of the Academy of Nutrition and Dietetics, Dietitians of Canada, and the American College of Sports Medicine: Nutrition and Athletic Performance (2016)](https://europepmc.org/article/MED/26920240)
- [TCS London Marathon 2026 Beginner Training Plan](https://www.londonmarathonevents.co.uk/sites/default/files/2025-10/2026_TCSLM_Beginner_Training_Plan.pdf)
- [The Big Half 10-week Training Plan (2026)](https://www.londonmarathonevents.co.uk/sites/default/files/2026-06/2026_TBH_10weekplan_B%26W_0.pdf)
- [Bosquet et al., Effects of tapering on performance: a meta-analysis, Medicine and Science in Sports and Exercise (2007)](https://europepmc.org/article/MED/17762369)
- [Almond et al., Hyponatremia among runners in the Boston Marathon, NEJM (2005)](https://www.nejm.org/doi/full/10.1056/NEJMoa043901)
- [Guest et al., International Society of Sports Nutrition position stand: caffeine and exercise performance (2021)](https://pmc.ncbi.nlm.nih.gov/articles/PMC7777221/)
- [Lauersen, Bertelsen and Andersen, The effectiveness of exercise interventions to prevent sports injuries, BJSM (2014)](https://europepmc.org/article/MED/24100287)