Marathon Training and Weight Gain

A couple of weeks ago I published a piece on the 5 most common marathon training mistakes.

One of the discussed potential mistakes, not increasing nutritional intake, garnered a lot of questions and concern.

Specifically, many runners worried that if they followed tip 4 “to increase calorie intake” and eat more to compensate for their increased miles, they’d gain weight, and thus were hesitant to adopt the idea.

The fear of weight gain is exactly why this problem remains one of most common marathon training mistakes!

To help clear up the issue and hopefully lend more support to my advice, I want to discuss the idea in-depth, especially as it relates to weight loss and marathon training.

Increasing nutritional intake to promote recovery

In the article, I outlined why during marathon training you need to eat more to fuel recovery.

Simply put, with increased mileage, harder workouts, and difficult long runs, your body needs calories (nutrients) to spark recovery.

Without fuel, the body can’t recover.

My recommendation was to add an extra 300 to 500 calories, in the form of healthy, nutrient-dense foods, to your daily calorie intake on harder workout days.

This will provide your body with the extra energy it needs for recovery.

Of course, this sparked a lot of fear about gaining weight. Many runners sent me questions like,  “if I eat an extra 300 to 500 calories, aren’t I going to gain weight?”

Luckily, the answer is no.

Why it’s likely you won’t gain weight when training hard, even when eating more

The body is an amazingly adaptable organism. Take for example what happens when you eat too few calories.

Many dieters know (or should know) that eating too little is detrimental to weight loss.

In the absence of calories, the body starts to slow its metabolism to conserve energy (remember that calories are simply a measurement of energy).

That’s why many extreme diets plateau after a few weeks of great gains.

You cut the calories and experience great gains for a short time period, but then the body adapts by slowing the metabolism and soon you need to eat even less calories to lose more weight until you can’t possibly cut out any more.

The same theory holds true when you increase calorie intake when training hard.

With the increased demand for nutrients and energy to fuel your workouts, your metabolism will increase if provided with the right fuel. Feed the furnace and it will start to burn hotter.

Of course, this doesn’t mean you can stuff your face with junk food and empty calories and not suffer consequences.

But, it does mean that adding an extra 300 to 500 healthy calories on hard running days, when your body’s demand for nutrients and fuel are at its peak, will result in faster recovery times with no impact on your weight.

However, this doesn’t mean that you will lose weight by training for a marathon.

Unfortunately, despite how logical it may seem, training for a marathon and losing weight don’t usually mix. In fact, when training for the marathon, it’s very likely you’ll gain weight – and it has nothing to do with overeating.

Not only is this common, but from a training and performance perspective, it might even be a good thing.

How can gaining weight be a good thing?

As you’re probably aware, one of the goals of marathon training is to improve your body’s ability to store and conserve glycogen for late in the race.

What many runners forget is that for every ounce of glycogen stored, the body also stores 3 ounces of water.

Add to that your desire to stay hydrated and you can easily put on a few pounds just by being hydrated and fully fueled for a long run.

If training is going well, you’ll also be burning fat and building muscle. The more miles you put on your legs, the stronger they will become.

In essence, you’ll be trading low density fat tissue for high density muscle tissue. Great for your performance, but not for the scale since muscle tissue is roughly 20 percent heavier than fat.

Conclusion – don’t use the scale as a measuring device

As you can see, when you’re in the best marathon specific shape – topped off glycogen stores, well-hydrated, and fit with plenty of muscle ready to run far – you’re going to be potential heavier than you’re out of shape, marathon unprepared self.

The bottom line is that the scale should not be the primary metric you use to measure your health, fitness, or marathon readiness.

While I understand weight loss is an important goal for many runners on the road to being healthier and performing better, don’t become a slave to the numbers on the scale. Eat right, fuel your training and you’ll see the results both in your appearance and your performance.