Why Some Runners Don’t Lose Weight
One of the most disconcerting experiences stepping on the scale at the end of a marathon training program only to realize you have gained weight. You may find yourself wondering, “How is that even possible?” There are a multitude of reasons why runners gain weight instead of becoming the stereotypically rail-thin athlete that many people associate with endurance sports.
You are overestimating how many calories you burn
In a study1 published in Journal of Sports Medicine and Physical Fitness, men and women each performed a controlled treadmill workout that was designed to burn either 200 or 300 calories, based on each individual’s measured biometrics. After the exercise, participants were asked to estimate how many calories they burned. They were then given free-access to a buffet-style meal and asked to refuel according to how much energy was expended. On average, athletes assumed they burned 650 calories more than they actually did, while consuming an excess of 250 – 300 calories. In reality, runners burn approximately 80 – 120 calories per mile, depending on body weight and running efficiency. They often feel that running provides an excuse to eat a limitless number of calories, which leads to weight gain.
You are slacking off the rest of the day
When in the midst of heavy training, it can be easy to decide you’ve earned a break from exercising the rest of the day. Stairs versus the elevator? Close parking spot versus one farther away? Post-dinner walk versus sitting on the couch? Many runners use their workouts as an excuse to slack off throughout the day. When this attitude is combined with overeating, gaining weight is likely.
© Big Stock Photo
Your body is storing water/fuel
Just because the scale reads a higher number today than it did yesterday, does that mean you have truly gained weight? For instance, if you weigh yourself and then immediately drink a 16-ounce glass of water, you would weigh exactly one pound extra if you weighed yourself a second time. Does this mean you gained one pound? In a literal sense, yes, but in the way we typically think of weight loss and weight gain in terms of fat, the answer would be no. Runners are encouraged to make two important nutrition changes, including drinking more water and eating more complex carbohydrates. Both can falsely lead an athlete to believe that he or she has packed on pounds, when in reality the body is simply storing fuel for future use.
You are experiencing inflammation
Inflammation is often responsible for mysterious weight gain, especially when an athlete is in the beginning stages of a new exercise program, or experiencing symptoms of over-training. When beginning a new running regime, athletes will be sore due to micro-tears in their muscles. The body’s natural repair response creates swelling in the area to adequately heal these minor injuries. This inflammation leads to water retention, which can make the scale read a higher-than-normal number. On the other hand, a runner who is training too hard may trigger the immune system to release mediators in the form of cytokines that produce an inflammatory response in the body, making the over-trained athlete susceptible to injury, infection, decreased performance and apparent weight gain.
You are gaining muscle
While the old adage “muscle weighs more than fat” does not necessarily make logical sense (after all, one pound of muscle and one pound of fat weigh the same), these bodily components do have different densities. Therefore, if the same volume of fat and muscle were compared side by side, fat would take up considerably more space than muscle. Within the first six weeks of starting a new running program, body composition will change. Many people become leaner, replacing excess body fat with new muscles in the core, calves, quadriceps and hamstrings. If starting an exercise program solely for weight loss purposes, it is often more useful to track how many inches are lost (i.e. from the waist) instead of tracking how many pounds you lose.
You are not recovering properly
Many runners also live very busy lifestyles, often juggling work, kids and training. Due to the “more is more” mentality when it comes to training, many runners do not receive an adequate amount of sleep. Besides helping muscles (and micro-tears) recover, sleep is also important for regulating stress hormones, such as cortisol. When too little sleep and increased levels of exertion via running are combined, cortisol is released into the bloodstream which triggers the body to go into “survival” mode, leading to increased sugar cravings and fat storage.
You are not exerting the same effort as before
There comes a point in every runner’s life when he or she reaches a plateau – fitness, weight loss or otherwise. If your running routine is the same as it has always been and nothing else (i.e. sleep or diet) has changed, yet you are gaining weight, your routine may be to blame. Over time, runners become more efficient at running, which leads to fewer calories burned per mile. Therefore, if a runner sticks with the same routine year in and year out, he or she will no longer receive the same benefit as in years past. Try changing up your routine by adding more mileage, faster paced runs or interval workouts.
Your thyroid is weakening
Finally, one reason some runners gain weight is due to changes to the thyroid brought on by running. While this point is contested in both scientific literature and in online fitness blogs (a review of both can be found in this Runner’s World article), the fact remains that thyroid function is affected by stress, and that running (especially high intensity/high mileage training) can signal to the body’s endocrine system to slow down its metabolism. When running is combined with other external factors, such as inadequate sleep or poor diet, it is certainly possible that the thyroid is to blame for a runner’s inability to lose weight.
Why Some People Don’t Get Fat
I’m pretty sure you’ve always wanted to know why some people never get fat, and this paragraph just needs to be here. Many beginning runners are jealous of their fellow teammates. “He eats twice as much as I do and he’s skinny as a rail. I just smell that burger and I immediately gain weight!” We all know those friends who spout this.
At the end of the day, there is always that runner who seems miffed that he or she could not eat as much as his or her peers – and they cannot understand why! I have always been lean, so life never seemed unfair for me, but I studied this a lot. Fat loss or fat gain is not mathematical and some people lose or gain body fat more easily than others.
Research2 suggests that when people overeat, about 80-90% of the excess calories are stored as fat, while the rest gets lost as heat. Fat cells that are overfed grow in size – that is how people become obese. Here are the four primary ways we burn calories.
1. Basal metabolic rate (BMR). Your body – liver, kidneys, heart, lungs and other organs – uses a consistent amount for energy every minute to sustain the needs required for you to just live. In other words, BMR is the amount of calories you burn doing nothing. Some runners believe their BMW is low and that causes them to gain weight quite easily. That is not the case. Only a few people have a “slow metabolism.”
2. Purposeful exercise. The amount of calories you burn while running, swimming, cycling or doing other sports activities.
3. Non-exercise activity thermogenesis (NEAT). Walking, brushing teeth, fidgeting washing dishes – this is energy used to maintain your posture when sitting or standing and muscle contractions that occur throughout the day apart from your purposeful exercise.
4. Thermic effect of food. This is the energy your body uses to process the food, digest it, absorb the nutrients and either store the excess energy as body fat or convert food into fuel for the organs or muscles. One thing is mathematical here – the thermic effect of food actually increases about 15% when you overeat because of the the additional energy required to process the extra food.
In the study, sixteen non-obese people (four females and 12 males), ranging in age from 24 to 36 years, volunteered to eat 1,000 extra calories a day for eight weeks.
Wrapping it up
Bottom line, the researchers showed that NEAT explains the huge variation in weight gain that occurs with the people in the overeating study. The subjects who were good putterers and fidgeters gained less. In the study, the average increase in NEAT was 337 calories per day, and it ranged from burning 691 calories more than baseline to burning just 98 calories less than baseline. The subject who actually burned the most calories walked around the research facility about 15 minutes more per hour than the others.
Despite popular belief, the “slow metabolism” is not a major cause of gaining weight. It seems that most often, runners who are easy gainers sit calmly, are mellow and don’t fidget. The athletes who are always skinny bounce around, walk and fidget. The information from this study, combined with the information from above, should help you understand why you are not losing weight while running.
1. Willbond SM, Laviolette MA, Duval K, Doucet E. Willbond SM et. al. Normal weight men and women overestimate exercise energy expenditure. J Sports Med Phys Fitness. (2010) 50(4):377-84. (link)
2. Bray GA, Smith SR. Effect of dietary protein content on weight gain, energy expenditure, and body composition during overeating: a randomized controlled trial. JAMA. 2012 Jan 4;307(1):47-55. doi: 10.1001/jama.2011.1918. (link)