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Preparing for a marathon takes more than just following a training plan. As I wrote about in my previous blog, there are other factors that make a difference come race day. But what sometimes gets overlooked (and has the potential to catapult you the next level) is your nutrition. Yup, believe it or not - what you eat throughout your training, and especially on race day, can greatly impact your personal marathon goals. “But where do I even begin?” you might be thinking? Well, don’t worry - Dr. Rob is here to help you avoid common marathon training nutrition mistakes. Let’s dive in to learn some helpful tips, shall we?


In my opinion, two of the most important factors determining performance on race day are training and nutrition. Most endurance athletes spend countless hours per week planning, training, and preparing their running sessions. But how much actual time do those athletes spend on nutrition? More times than not, the answer is not enough.

I’m constantly reminding my clients not to take their nutrition for granted, warning them that neglecting their diet could jeopardize all the hours and days of their hard training. But here’s the good news - with just a few modifications to your diet, any athlete can ensure they are 100% prepped and ready to go. See below for my top 4 tips:


While training, and especially on race day, you want to make sure you are maintaining a normal blood sugar level without too much fluctuation. Remember, when your blood sugar dips, so too will your energy. And when you hope to run 26.2 miles, you can't afford to give out midway — you’ll need enough gas in your tank to take you to the end.

In addition to eating before your workouts, you should be fueling throughout your long workouts. You're likely to burn through your breakfast calories within an hour or so, so I recommend that my clients eat BEFORE they feel hungry. Depending on your size, you should aim to consume a small snack or meal an hour to keep your body working at its peak. This should be something that you know is good on your stomach but light enough that it won't come back up on you while you are training. Stick to more complex carbohydrates with small amounts of proteins and fats thrown in. This can include a banana with peanut butter, pasta, or rice.

What does a mid-training snack look like? You need carbs for fuel — gels, sports drinks, power bars

or dried fruit all do the trick. But what kinds of food you eat depends on what your body can tolerate, so explore different options during your training to learn what foods will work specifically for you during the long run (including race day). For example, many energy gels are known to give digestion problems due to the high levels of maltodextrin and the sharp

fluctuations of glucose levels in the body. The “runs” after a race is a well-known issue for people who have taken certain energy gels during a race. I have certainly experienced this myself on many occasions while trying different and new products over the years. So, experiment BEFORE the big day to see what works best for you!


Just as important as the food you consume is the amount of fluids you take in before, during, and after training...and of course on race day.

During a marathon, one of your main concerns should be to prevent dehydration, which not only slows your performance, but also delays your recovery. That's why it's important to calculate how much you sweat and what is the content of your sweat so you know the exact amount of water and electrolytes you need to replenish those lost fluids and minerals.

So how do you figure out your sweat rate? A simple way to analyze this is without drinking anything, weigh yourself before and after an hour-long run. If you lose two pounds of water, that's equivalent to one quart, meaning you should drink eight ounces every 15 minutes. To better help your specific needs, there are various sweat calculators on the internet that will help you do these calculations.

You can even get fancy and have a lab do an analysis of your sweat by wearing a special patch and running or cycling for about 20 minutes, Hand off the used, sweaty patch to the lab and they will give you a thorough and detailed analysis of your sweat rate and content so you can REALLY dial things in.


A lot of marathoners think if they lose weight, they'll be lighter and run faster. While this may sound correct, cutting too many calories from your diet will lead to low energy and not allow you to recover appropriately. And when you don't eat enough, your body doesn't have sufficient fuel to power you through your workouts.

What I have seen happen to clients who lose too much weight is they lack the needed energy to log those long miles. To perform your best, I recommend either fueling up an hour or so before a run or refueling within an hour after one. And make sure you're getting sufficient calories throughout the rest of the day, too.

With that said, training for a marathon doesn't give you the full luxury to eat whatever you want, anytime you want. I know what you're thinking: "But I just logged 16 miles! I can have that sleeve of Girl Scout cookies!"

Here's the problem: Outside of training, you're likely moving not as much as you were during training. Additionally, the stress placed on your body by training has created a level of inflammation and stress that needs time and nutrients to recovery. You're body needs the appropriate types of calories, minerals, and nutrients to recover and also to maintain appropriate body mass (even produce greater muscle strength and mass).

Therefore, it is okay that you reward yourself every now and then with something you enjoy. However, just because you ran 16 miles does not mean you need to eat 16 miles worth of calories of cookies or cake for that day. If you are struggling with the nutrition component of your training plan, speak with a sports nutritionist, especially one who works with runners and triathletes. They will be able to point you in the right direction of what to do and when.



So you’ve done all the training and race day is a week away. This is when your nutrition becomes even more important. During this crunch time, I tell my clients to think about their marathon diet in 3 separate time chunks: (1) the week leading up to the big race (2) the day/night before and (3) and the all-important day-of. Here are my tips for runners during this crucial time.

The Week Leading Up

The several days prior to running a marathon are no time to limit your calorie or carbohydrate intake. The meal you eat the morning of the race alone can't provide you with enough energy, so you'll have to use some that's stored up. Your body stores carbohydrates as glycogen to use when it's running on empty. To build up your glycogen stores for race day, you’ll need to relatively bump up your calorie and carb intake the week prior to the marathon (but don't go overboard).

During the days leading up to your race, focus on including plenty of complex carbohydrates in your diet. These can help provide the energy you need to perform. Foods I suggest incorporating are whole-grain bread, whole-grain pasta, potatoes, rice and legumes.

Dr. Rob Quick Tip: Load up on nitrates. Nitrates are found in plant foods, like beets, arugula, and swiss chard. When consumed, they are converted into the potent vasodilator, nitric oxide, which increases blood flow to the heart and working muscles. It also increases the efficiency by which our muscles produce energy from oxygen. This means you’ll be able to race faster and longer.

The Day Before

I tell my clients to try to eat meals that are balanced in protein, fat and carbohydrates. For example, you can have oatmeal with peanut butter for breakfast and salmon with rice for lunch or dinner. Try to avoid fruit and vegetables (i.e. due to their high fiber content, they may increase your risk of an upset tummy on the actual race day).

Dr. Rob Quick Tip: Steer clear of greasy foods and alcohol the day and (especially) evening before a marathon. These can cause unwanted digestion issues and dehydration you'll want to avoid mid-run.

Race Day

The food you consume on your training days is the food you should stick with for the race. NOTHING NEW ON RACE DAY! Now is not the time to change anything up! So ensure you have your standard race breakfast that you have trained beforehand. And what should that breakfast look like? Be sure to avoid high fiber, high fat and high protein foods. Aim for at least 100 grams of carbohydrate and of course, drink enough fluid and check that your urine color is light yellow or clear.

Dr. Rob Quick Tip: Running on a full stomach can be uncomfortable, so plan to eat breakfast two to four hours before the start of the race.

If you’re a runner looking for more tips on how to excel in your marathon training, please touch base with me using my website, , give me a call at 516-387-0053, or reach out to me via email at .

If you enjoyed this blog, please share it out on your social media, at work, or with your friends and family. I hope this has helped you and I hope that you tune in to future content that will be posted on this page.


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