How to Avoid Weight Gain Before and After Marathons

Smiling runners drinking water after marathon

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Many new marathoners sign up for the race with hopes that the training will help them to get a leaner, fitter body. In some cases, the long miles and endless hours of running will result in weight loss. But in other cases, it results in weight gain. And to make matters worse, weight gain after a marathon gain can happen as well.

So why does marathon weight gain occur? Some published studies have shown that weight loss is more common than weight gain during and after training is complete. But there have also been small studies showing that weight gain may occur in some people. And if you find that you are gaining weight during or after a marathon, a quick scan of running-related articles will show you that you are not alone.

A small study of marathon runners conducted at Tufts University found that while some people lost weight during training, an equal number of people gained weight in the months leading up the event.

There are several key factors that can affect your weight during training. To keep your training on track and your weight healthy before and after a marathon, consider a few key factors.

Why Marathon Weight Gain Occurs

Depending on when weight gain occurs, there may be different causes of marathon weight gain.

Weight Gain Before a Marathon

During marathon training, your running mileage increases. However, your appetite is likely to increase as well. As a result, you may boost your food intake. While it is important to consume enough calories to fuel your runs, it can be easy to consume too many calories if you're not careful.

Many runners (understandably) feel entitled to an indulgent meal or regular desserts after pounding the pavement for hours. The problem is that you may end up consuming more calories than you burned during your runs. The increased calorie intake leads to weight gain.

One of the most commonly cited causes of marathon weight gain is increased food consumption. Often the foods chosen after hard workouts and long runs are high-fat, empty calorie foods—or foods that don't provide smart nutrition to fuel your training.

Another explanation is that during marathon training your body is learning to store carbohydrates as fuel (glycogen) for your long runs. Those glycogen stores are important for completing long runs successfully. They will also help you to avoid "hitting the wall" on race day.

But those glycogen stores may cause you to see a couple of extra pounds on the scale on certain days. Your body requires additional water to break down and store glycogen. This extra water shows up as (temporary) extra weight on the scale.

Lastly, as you're training, you're building muscle mass. Muscle is denser than fat, so you may see an increase in your overall body weight.

So should you worry about weight gain before the marathon? What matters most is how weight gain affects your training or race outcome. There has been a published study showing that the most successful marathoners are those that decrease their body weight by 3–4 percent during training. However, this study did not evaluate body composition (i.e. muscle mass or water weight).

If you are concerned about weight gain during marathon training, use different methods to evaluate your body size. Invest in a body weight scale that can show not only overall weight, but also body fat percentage. Some scales even track water weight.

Your body fat scale may indicate that while your weight is increasing, your body fat is decreasing during training. This means that your body is putting on more muscle and losing fat. Increased muscle mass can help you to run more efficiently during the marathon.

You can also take note of how your clothes fit. If your weight is increasing but you notice that your clothes are getting looser or fitting the same, it is likely that your body composition is changing for the better.

While several factors can lead to pre-marathon weight gain, there are different types of weight gain. Weight gain from excess calorie consumption can—and in some cases should— be avoided. But you don't necessarily want to avoid weight gain from increased muscle mass or efficient glycogen stores.

Weight Gain After a Marathon

Post marathon weight gain is more common than weight gain during training. The reason is fairly straightforward.

Many marathoners get used to consuming more calories than normal to fuel their training runs. It can be tough to put the brakes on these eating habits once the marathon is over. And since you're not running as much as you were doing training, all those extra calories can quickly lead to weight gain.

Those who complete fall marathons are especially prone to the post-marathon weight gain because their marathons are followed by the winter holiday season when there's not a lot of time to exercise, but plenty of opportunities to eat.

Also, you may lose some muscle mass after the marathon if your training hours decrease substantially. A less muscular body requires less fuel, even at rest. So you need even fewer calories to sustain your metabolism.

While weight gain during training can be beneficial in some circumstances, weight gain after your marathon is probably not a good thing. Increased weight from the overconsumption of food (a calorie surplus) is likely to be stored as fat.

How to Prevent Marathon Weight Gain

There are different strategies that you can use to manage your weight gain during and after training for a marathon. But the first step is to make sure that you are at a starting at a healthy weight

A body mass index (BMI) calculator or a body fat percentage calculator can give you a general idea if your weight is healthy.

Once you know that you are at a healthy weight, use a calorie calculator to make sure that you are consuming the right number of calories each day.

Tips to Avoid Weight Gain During Marathon Training

Once you know how many calories you should eat each day, start to log your food intake and make sure that there isn't a big gap between the two numbers. If you find that you are eating much more than you need to, evaluate your food habits and consider making these changes.

Reduce Calories Consumed in Beverages

Sports drinks can be high in calories. Make sure that you aren't consuming them on shorter runs when water will suffice. And consider reducing your intake of other high-calorie beverages such as alcohol and caffeinated sodas. Not only do these drinks add calories, but drinking them can lead to dehydration, which can cause fatigue during runs.

Focus on Fiber and Protein

Build meals around healthy lean sources of protein (such as chicken breast, legumes, seafood, or turkey) and fiber-rich carbohydrates (such as green leafy vegetables, whole grains, or fresh fruit). Protein helps you to build and repair muscle tissue after workouts. And both fiber and protein help you to feel full after eating. This will help you to combat hunger cravings that can happen when you train more often.

Choose Fats Wisely

During training, you might be able to consume slightly more fat than you would typically. But that doesn't mean that you should eat any fat in any quantity. Avoid fried foods and saturated fat. Stick to sources of poly- and monounsaturated fat, such as nuts, seeds, plant-based oils, and avocado. Consume these fats in moderation, because even though they provide heart-healthy benefits, they still contain nine calories per gram.

Plan Ahead

Marathon training takes a lot of time. Many runners find themselves running from home to work to training without enough time to stop and eat a full meal. It's smart to carry a few snacks with you so that you are not stuck buying food from a vending machine or fast food restaurant.

Focus on Performance

Keep in mind that in order to reach your marathon goals—whether it is simply to finish the race or set a PR—your body will change during training. Your legs may get bigger as you build strong muscles in your quads and hamstrings. You might notice your winter boots getting tighter around your calves.

These changes may come with an increase in the number on the scale, but they also come with a stronger, faster, more efficient body. And that's a good thing!

Try to focus on performance goals: completing workouts consistently, increasing endurance, getting faster, and boosting your mental strength. These are lifelong skills that will stay with you and help you to maintain a healthy, fit life even after the marathon is over.

Postpone Weight Loss Goals

While you might lose weight naturally during training, trying too hard to restrict calories when your mileage is increasing can cause fatigue, frustration, and lack of motivation. It is nearly impossible to complete a long run if your body is lacking calories and especially carbohydrates.

If your ultimate goal is weight loss, focus on food quality rather than on food quantity. Eating healthy meals and skipping empty calorie foods may help you to reach your weight loss goal. If not, wait until after the marathon is over to attempt a dedicated weight loss program.

How to Avoid Post-Marathon Weight Gain

If you're worried about gaining weight in the months after completing a marathon, here are a few things to try.

Keep Exercising

Some marathoners are so burned out mentally and physically from the marathon that they completely stop running and working out. Try not to wait too long after the marathon to get back to running because once you get out of your running habit, it's tough to get back into it. Even though you'll be recovering for a few weeks, you can still do short, easy runs or easy cross training in the days following your marathon.

Pick Another Race

You don't have to plan to run another marathon, but having the date of another race on the calendar will motivate you to keep running. Look for races in your area and running groups that are training for upcoming races.

Celebrate in Moderation

After you've completed a marathon, it's tempting to overindulge while you're celebrating your achievement with family and friends. It's fine to celebrate your accomplishment with an indulgent meal and some drinks, but try not to let it turn into a month-long celebration. Also, you should learn tips for portion control and avoiding holiday weight gain.

Choose Healthy Rewards

Yes, it's fun to celebrate your accomplishment, but there are ways to do that other than eating and drinking. Treat yourself to a much-needed post-marathon massage or buy yourself some new running gear. Getting some new running clothes will also keep you motivated to continue running.

Keep Healthy Snacks Habits

Even though you may not be running as many miles each week, you may still find yourself feeling hungry all the time. Whether you're at work, home, school, or on-the-go, make sure you're always prepared with healthy snacks so you don't eat unhealthy, high-calorie foods because they're more convenient.

Track Food Intake

After the marathon, recalculate your caloric needs based on your reduced activity level. Then try to stay within the recommended numbers.

It's easy to consume too many calories when you're not really aware of how much you're eating and drinking. Once you start keeping track of your calories, you may be shocked at how many calories you're taking in, and you'll be able to identify areas for improvement. And tracking your calories may actually make you think twice before going overboard.

Display Your Finish Line Photo

Whether it's on your desk, your refrigerator, or your wall, display your race photo proudly. Being reminded of your marathon completion will help motivate you to continue running and you'll be inspired to fit into that marathon outfit.

A Word From Verywell

Choosing to run a marathon is a big commitment. It takes substantial physical and mental energy—especially when you have other priorities in your life such as school, a family, or a career. Trying to lose weight at the same time is likely to be too much.

As you train, try to focus on staying healthy. Eat well, get enough rest, and follow a smart training plan to avoid injury and stay motivated. If your weight fluctuates slightly, don't worry about it unless it begins to affect your performance.

If the weight gain continues to be problematic, consider investing in an appointment with a registered dietitian with expertise in running or sports performance. Together you can develop a meal plan that helps to keep your hunger at bay while keeping you properly fueled for your workouts.

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Article Sources

Verywell Fit uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial policy to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
  • Barandun, Ursula et al. “Running speed during training and percent body fat predict race time in recreational male marathoners.” Open access journal of sports medicine vol. 3 51-8. 2 Jul. 2012, doi:10.2147/OAJSM.S33284

  • Huddleston, J. Tufts’ President’s Marathon Challenge: Can YOUR Body Handle the Physiological Change? The Friedman Sprout. Friedman School of Nutrition Science and Policy. Tufts University. March, 2010

  • Janssen, G., Graef, C., & Saris, W. (1989). Food Intake and Body Composition in Novice Athletes During a Training Period to Run a Marathon. International Journal of Sports Medicine, 10(S 1), S17–S21. doi:10.1055/s-2007-1024949

  • Williams, Paul T. “Asymmetric weight gain and loss from increasing and decreasing exercise.” Medicine and science in sports and exercise vol. 40,2 (2008): 296-302. doi:10.1249/mss.0b013e31815b6475

  • Williams, P T, and P D Wood. “The effects of changing exercise levels on weight and age-related weight gain.” International journal of obesity (2005) vol. 30,3 (2006): 543-51. doi:10.1038/sj.ijo.0803172

  • Zouhal, H., Groussard, C., Minter, G., Vincent, S., Cretual, A., Gratas-Delamarche, A., … Noakes, T. D. (2010). Inverse relationship between percentage body weight change and finishing time in 643 forty-two-kilometre marathon runners. British Journal of Sports Medicine, 45(14), 1101–1105. doi:10.1136/bjsm.2010.074641