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Preparing for a marathon is a significant process in itself; the intense hours we put into training ourselves to run longer distances do more than just prepare us for the final day. They give us a sense of purpose, a drive towards self-improvement and help build self-assurance as we see our own progress.

In order to get the most out of this, it becomes extremely important to understand how nutrition can affect one’s marathon-training. A diet that fuels, complements and even helps our bodies recover from the training augments the changes we see – both in our performance and our frame of mind. Here’s what this diet ideally consists of:

1] Plenty of whole grains, fruits and vegetables

Carbohydrates are broken down into simple sugars, like glucose, and are a very important source of energy.

Our muscles contract when we exercise; to do this, they require energy, which they mainly get from glycogen, i.e., a form of glucose reserved in the muscles and the liver.

Once the muscle glycogen runs out, the body uses other forms of glucose, including the one present in the blood, as fuel; but if even those levels are low, we experience weakness, hunger and dizziness.1, 2 

For these reasons, it’s necessary to maintain adequate levels of glycogen and blood glucose in the body. Some athletes even prefer to go over and above the normal levels of muscle glycogen, through what’s termed as ‘carbohydrate loading’. This entails significantly increasing the amount of carbohydrates in one’s diet, ranging from 5 g to 12 g per kg bodyweight (per day), depending on the exercise programme.3 Doing so would improve one’s performance in exercises that last more than 90 minutes, with marathon running being a prime example.

The more we exercise, the higher our requirement of other nutrients (like vitamins and minerals) becomes as well, so it’s best to get our carbs from nutrient-rich sources like whole grains, fruits and vegetables.

2] The right kind of carbohydrates, eaten at the right time

While we need sufficient levels of glucose in our blood while we run, there’s another catch: we also need these levels to be stable. Forms of carbohydrates that break down into glucose very quickly can lead to a blood sugar rollercoaster, where the body experiences a dramatic spike in blood sugar that’s followed by a sudden drop.4

Choosing carbohydrates wisely, based on a value called the glycemic index (GI), makes all the difference when training.5

The GI of a food indicates how much it’ll raise one’s blood sugar; medium to low GI foods are better at stabilising blood glucose and insulin responses during a subsequent period of exercise. These can be consumed just before exercising or even while warming up, to fuel one through the run.3, 6

Glycemic Index (GI)Glycemic Index (GI) ValuesExamples
Low0 – 55Whole grains, seeds, legumes, most fruits
Medium56 – 69Millet, basmatic rice, sweet potatoes, bananas and honey
High70 or moreMelons, pineapple, white bread, bagels, most breakfast cereals and refined rice varieties, and baked goods


3] The right kind of fats, to fuel a longer workout

Like carbohydrates, fats also fuel our workouts; the main difference is they take longer to reach the exercising muscles, once consumed.

Since higher-intensity workouts would require fuel more quickly, these exercises would generally require carbohydrates as a pre-workout. Fats, on the other hand, can energise low-intensity exercise (a slower pace of exercise) for prolonged periods of time, which makes consuming them, too, important for marathons.7

While the various fats we get in foods play their own unique roles in the body, workouts would specifically benefit from the consumption of medium-chain fatty acids (MCFAs), since these fats are absorbed more easily than others; their calories are more efficiently turned into energy (especially for those training regularly) and used by the body, being less likely to get stored as body fat.8

Their positive impact on exercise performance, however, hasn’t been completely established yet; the studies conducted so far are often contradictory and not very reliable, because of the varied exercises they involved and the small number of subjects.

Having said that, it’s clear enough that MCFAs are satiating and healthy; 1 teaspoon of oil that contains MCFAs, such as coconut oil and palm kernel oil, with small amounts found in dairy products, may enhance performance.

4] A sufficient amount of water

Although it goes without saying, it’s still necessary to reiterate that being hydrated is essential when we run, especially in a hot climate. Losing more than even 2–3% of our water content is considered as dehydration, and may compromise performance, with a higher percentage even causing other health hazards.

Hydrating prior to exercising is essential, with about 5-7 mL of water/beverage per kg body weight being recommended at least 4 hours prior to a run.6

If the colour of one’s urine is dark or highly concentrated, an additional amount  can be consumed (about another 3–5 mL/kg) about 2 hours before the event.6

One should hydrate during the run, too, with small sips.

4] Electrolytes 

Electrolytes are minerals (like sodium, potassium and magnesium) that help the body maintain a healthy balance of water within and outside the cells.

A significant amount of perspiration runs the risk of an individual losing their body’s electrolytes through the sweat. This is especially true for regular exercisers– the body tends to hasten the time it takes, and enhance its capacity, to sweat, to regulate its temperature faster.10

Another thing to watch out for is diluting the electrolytes by drinking a lot of water. This is commonly seen with long-distance runners when their (large amount of) water-intake isn’t accompanied by electrolytes-intake, causing several issues, including muscle and nerve damage.11

There’s no downside to consuming electrolytes when hydrating; a slightly higher-than-usual amount of electrolytes in the body is easily balanced out by the kidney simply holding on to more water (instead of expelling it).

While sports drinks might offer the body with more fuel because they contain more calories and are also more easily available, it’s nevertheless important to focus on natural electrolyte-rich drinks, like coconut water or fresh lemonade, for a better nutritional value.

5] Protein (after a run)

A necessary part of building muscles involves muscle breakdown, in order to rebuild it to be stronger.

This process of muscle rebuilding needs amino acids (the blocks that make up protein) from our bloodstream, which makes consuming protein-rich foods imperative, even and especially after a workout.12

Meat, dairy and seafood are great sources of protein, while legumes and seeds give us a good mix of both proteins, for muscle rebuilding, and carbohydrates, for replenishing glycogen stores.

6] Plenty of omega-3 fatty acids

The muscle breakdown that occurs after exercise also produces some amount of inflammation; that’s what, researchers believe, causes soreness after a workout.

Since omega-3 fatty acids make anti-inflammatory compounds in our body, they aid recovery (so effectively, in fact, that they’ve been compared to anti-inflammatory drugs like ibuprofen).13, 14 These fats have also been proven to promote cardiovascular health– important not only for fitness but also longevity!

Moreover, it’s important to consume a sufficient amount of omega-3 fats to compensate for our intake of omega-6 fats, which, on the other hand, increase inflammation and are ubiquitous in the modern diet (being rich in vegetable oils). Although inflammation is a critical function for our immune-response and for us to adapt to exercise, it needs to be kept in check by maintaining a balanced ratio of these two fats.

Omega-3 fats can be found in fish, avocados, walnuts, chia seeds, flaxseeds and their oils.

7] Colourful foods rich in antioxidants

Inflammation is abetted by free radicals, which you’ve probably already heard of in a negative light. That’s because they’re infamous for causing damage to the cells and structures in our body – but that’s mainly when they’re in excess. In certain quantities, they actually play a vital part in several processes.

The production of free radicals is believed to increase anywhere from twofold to threefold as we progress from exercise to exhaustion.15 That’s something our body is prepared for. It uses a portion of these free radicals for the multiple purposes they serve, and then neutralises the excess with molecules known as antioxidants. Our body has a natural store of antioxidants that’s (ideally) constantly replenished through the nutrients it receives from our diet.

Eating plenty of colourful foods is especially helpful in restoring our natural antioxidant system. Their natural pigments, called ‘phytonutrients’, have several health benefits, including antioxidant properties. For instance, the reason turmeric (haldi) is so widely acknowledged for its powerful antioxidant properties is because of the yellow pigment it contains, called curcumin.16 

The reduction of inflammation post exercise (with the help of both antioxidants and omega-3 fats) goes on to boost our health in even other ways like relieving painful joins and promoting heart health.17, 18

Since our body is directly affected by the nutrients we provide it with, improving the nutritional value of our meals has a ripple effect on every aspect of our health. The remarkable changes that can be seen when we use nutrition as a tool to meet and even enhance our lifestyles are fascinating to witness. Focusing on your nutritional needs while training for a marathon is a great place to start.


1. McArdle WD, et al. Exercise Physiology: Nutrition, Energy, and Human Performance. Lippincott Williams & Wilkins, 2010.

2. Whitney E, Rolfes SR. Understanding Nutrition. Cengage Learning, 2015.

3. Burke LM, et al. J Sports Sci 2011, 29 Suppl 1: S17-27.

4. Burn G. Healthy Mind and Body All-in-One For Dummies. Wiley, 2009.

5. Wilkins LW. Diabetes Mellitus: A Guide to Patient Care. Lippincott Williams & Wilkins, 2007.

6. Jeukendrup AE. J Sports Sci 2011, 29 Suppl 1: S91-99.

7. Horowitz JF, Klein S. Am J Clin Nutr 2000, 72(2): 558s-563s.

8. Papamandjaris AA, et al. Life Sci 1998, 62(14): 1203-1215.

9. Breckenridge WC, Kuksis A. J Lipid Res 1967, 8(5): 473-478.

10. Lee J-B, et al. PLoS ONE 2014, 9(4): e93976.

11. Rosner MH, Kirven J. Clin J Am Soc Nephrol 2007, 2(1): 151-161.

12. Clarkson PM, Thompson HS. Am J Clin Nutr 2000, 72(2): 637s-646s.

13. Zafari M, et al. Caspian J Intern Med 2011, 2(3): 279-282.

14. Maroon JC, Bost JW. Surg Neurol 2006, 65(4): 326-331.

15. Davies KJ, et al. Biochem Biophys Res Commun 1982, 107(4): 1198-1205.

16. Chainani-Wu N. J Altern Complement Med 2003, 9(1): 161-168.

17.    Bala A, Haldar P. OA Arthritis 2013, 1(2): 15.

18.    Esterbauer H, et al. Free Radic Biol Med 1992, 13(4): 341-390.

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