Why You Might Not Lose Weight While Running

While training for optimal performance on race day is the main focus for our coaches here at RunnersConnect, many of the athletes we coach set secondary goals to lose weight and generally desire to be healthier overall. Certainly, sometimes these two goals – setting a new pr and losing weight – go hand-in-hand, but as coaches we tend to focus on letting weight loss come naturally as the body adapts to training and new levels of fitness.

However, we can appreciate that runners might want to speedup the weight loss aspect of training, which is why I wrote this earlier post on losing weight while running. Unfortunately, sometimes when a runner first begins serious training, the needle on the scale doesn’t immediately go down, and sometimes it can even head in the wrong direction. This trend can be frustrating and demoralizing to many runners. However, if you understand the science behind initial weight loss and the practical reasons for why this occurs, you can temper yourself from getting discouraged and make positive and long-term gains both to your overall fitness and to your race times. So, here are some reasons why you might actually gain weight when training hard.

The Scale is a Trickster

If the scale were a human, he/she would be considered a deceptive trickster. A scale only provides one number, your absolute weight, which isn’t always an accurate measurement of what is happening in your body. Drink a gallon of water and you’ve instantly gained 8.3 pounds. Remove a kidney and you’ve lost 2 pounds. Extreme examples, I know, but I think it proves that your absolute weight on a scale isn’t always a truthful assessment of changes in your weight, or more importantly your fitness. Here are just a few reasons the numbers on the scale will lie to you:

You will store extra water

When you increase your training to gear up for your goal race, your body begins to store more water to repair damaged muscle fibers and to deliver glycogen to the working muscles. Likewise, you may even be drinking more water to supplement the miles and ensure your hydrated. All this water adds pounds to the scale, but isn’t indicative of your actually weight loss.

Muscle weighs more than fat

While you’re not going to turn into a body builder after just a few days of running, your body will slowly begin to build muscle and burn fat. While this is great news for your overall fitness and race times, you’re actually gaining weight by supplementing low density fat tissue for high density muscle tissue. While it may not look great on the scale, it’s much healthier and will help you to continue to get faster and fitter.

Looking for short-term results

It takes a deficit of 3500 calories to lose one pound. Ideally, you should target a 300-600 a day calorie deficit if you want to lose weight safely and be healthy. This means, you can expect to lose about 1-2 pounds per week. Checking the scale every morning is going to revel very little about your long-term progress or the actual state of your weight loss. If you weigh yourself everyday, you’re simply measuring day-to-day fluctuations in your hydration levels  and other non-essential weight metrics. Just like you wouldn’t expect a 1 minute drop in your 5k PR after a week of training, don’t expect a 5 pound weight loss after your first week of running.

Eating Too Much to Compensate

You burn more calories while running than almost any other activity you can do. Unfortunately, while the energy demands of running are high, this does not mean that you can eat a big mac and a donut guilt-free and still lose weight.  I often hear runners rationalize their dessert intake by saying, “hey, I ran 5 miles today, I deserve it”. Likewise, I see many running groups meet-up at Starbucks or the local coffee shop after a weekend run. Unfortunately, an iced latté and a small scone will quickly eliminate any caloric deficit from the run and negate possible weight loss. While running does burn calories, you have to be careful not to quickly or inadvertently eat them back with non nutrient dense foods.

Likewise, as mentioned in my article on how to lose weight and still run well, you should be providing your muscles with the necessary carbohydrates and protein to recover. This is a delicate balance, and probably the most difficult element to losing weight while running. As a coach, I think it is more important to focus on recovery and ensure that your muscles have the nutrients they need to rebuild. The harder you train, the more often you will get hungry and the real secret is to refuel with nutrient dense and high quality foods. Sacrificing recovery for a few less calories is not a good long-term plan. The numbers on the scale are arbitrary and focusing on them can be detrimental to your long-term progression. If you can continue to build your fitness and training levels, you’ll be running farther, faster, and be much healthier overall.

Calculating how may calories you burn while running

On average, a runner will burn 100 calories per mile, dependent on weight. 

Hidden Calories

Many marathon runners automatically assume they are going shed pounds with all the extra mileage they are putting in. However, not only should you ensure that you’re recovering properly after your hard workouts and long runs by eating the right foods, you also need to account for what I call “hidden calories”. Primarily, hidden calories come in the form of sports drinks and energy gels, which have a high caloric content.

It’s critical that you practice your fueling strategy during your long runs and hard workouts for optimal performance on race day. Likewise, to sustain high levels of training and to complete long and arduous marathon workouts, you need to fuel during your training sessions with sports drinks and energy gels.

However, this also means that the total number of calories you will burn from these long runs and hard workouts will be less than you might realize. Again, for optimal performance and training progression, you need these extra calories. Unfortunately, they can also be the reason you might not see the weight loss on a scale.

Focus On The Right Metrics

The bottom line is this: running will not automatically result in an immediate weight loss. Yes, running burns more calories than any other form of exercise, but the scale should not be the primary metric by which you gauge your fitness level and training progression.

While I understand weight loss is an important goal for many runners, don’t become a slave to the numbers on the scale. Pay attention to how you feel – do you have more energy, feel stronger, starting to fit into your clothes better? While not absolute measurements, these emotions are a much more accurate measurement of your progression.