The Best Foods to Eat – And Avoid – When Training for a Marathon

Training for a marathon is no easy feat. It takes time, dedication and perseverance. For most people, training lasts 12-20 weeks, with three to five runs per week. 

Physical training is only one piece of the puzzle. If you’re not fueling your body with the right foods, you won’t get the results you want. 

If you’re training for a marathon, it’s important to know which foods to eat – and which foods to avoid.

The Best Foods to Eat When Training for a Marathon

Nutrition is crucial when training for a marathon. The right foods will keep you going and help you perform your best. 

Which foods should you be incorporating into your diet during training?

Before a Long Run – Foods with a Low Glycemic Index

If you’re going on a long, 10-12-mile run for your training, you’ll need sustainable fuel for your body. Foods with a low glycemic index are your best bet and should keep you going for 1-2 hours.

What are low glycemic foods? The term “low glycemic” refers to foods that are low on the glycemic index (GI). The GI is a tool that measures how much a food increases blood sugar levels. Let’s say that a food has a GI of 35. This would mean that the food boosts blood sugar 35% as much as pure glucose.

High-glycemic foods generate a quick blood sugar spike, while low-glycemic foods have a much slower and smaller effect on blood sugar.

Low glycemic foods have a GI of 55 or less. Most fruits, vegetables and legumes fall into this category as well as nuts and low-fat dairy products.

Examples of low GI foods include:

  • Brown rice
  • Non-starchy vegetables
  • Butter beans and peas
  • Most fruits
  • Leafy greens
  • Steel-cut oatmeal
  • Whole-grain bread

Low GI foods are generally high in fiber, which slows down the absorption of the natural sugars that give you energy. The slow absorption means that your meals will keep you steadily energized for longer instead of giving you a quick burst of energy (and a quick crash).

After Training – Protein to Repair

The foods you eat after a training session are just as important – if not more important – than the foods you eat before training.

The right foods will give you the nutrients you need to repair and recover quickly – and stronger than before.

High-protein foods will help build and maintain muscle mass. Protein is satiating, so you’ll feel fuller for longer.

If you notice that you have intense sugar cravings after a long run, it’s because your body is trying to tell you that it needs more fuel. Sugar is a quick fuel source, so the body craves this fast form of energy.

Protein can help curb these cravings while providing the fuel your body desperately needs after training. 

Great sources of protein include:

  • Poultry, like chicken and turkey
  • Eggs
  • Lentils and beans
  • Fish
  • Low-fat yogurt or cottage cheese
  • Nuts and seeds, including chia seeds and quinoa (yes, quinoa is a seed)

Make sure that you’re getting enough protein throughout the day to support your recovery and maximize the benefits of training.

Foods to Avoid

Nutrition is more important than you think. In fact, improper nutrition can contribute to injuries that could knock you out of the game. A shoulder injury can easily keep you out of work for 30 days. That’s a month of valuable training time, and could very well prevent you from competing.

Be smart about your food choices, and do your best to avoid:

  • Junk food, like cakes, candy and other high-sugar foods
  • Processed foods that may be high in calories and fat
  • Foods that are high GI, like white bread and most breakfast cereal

High GI foods may give you a quick burst of energy, but that energy boost won’t last long. Halfway through your run, you may find yourself puttering out. 

Nutrition is key when it comes to marathon training. Fuel your body with the right foods, and you’ll have the energy to get through each training session and give it your all.


  1. Thanks for the advice. I have a new years resolution to do a marathon this year, so fingers crossed. I want to know what and what not to do.

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