Put an End to Midseason Weight Gain


By now you’re likely well into your summer training and competition season, so how the hell are you gaining weight?! Midseason weight gain is surprisingly common, especially for endurance athletes. Sometimes it’s perfectly normal and may actually improve your performance, but often it’s caused by simple misconceptions about training, fueling, and recovery. Whether you’re a cyclist, runner, or triathlete here’s how to have a lean and fast summer.

How mid-season weight gain can be positive

While endurance athletes generally benefit from being lighter and leaner, there are instances when weight gain can be a sign of progress.

Increased glycogen storage:

The more you train the more glycogen your muscles store. There’s an upper limit to glycogen storage (about 500 grams or 2000 calories), but people don’t automatically max out their glycogen storage; it increases as a response to training. Each gram of glycogen stores 3 grams of water with it (1g CHO + 3g H20 = 4 grams), so 500 grams of CHO stores 1500 grams of water with it, accounting for 2 kilograms of total weight. Increased glycogen storage doesn’t account for 2 kilograms of weight gain, though, because you always stored some and there’s no gauge to determine the increase from pre-training glycogen storage to your level of storage.

Increased plasma volume:

Improved aerobic fitness and acclimation to exercising in the heat lead to concurrent increases in plasma volume, which is going to contribute to minor weight gain. The physiological advantage from increased plasma volume is so great, however, that it far outweighs (get it, haha!!) the small increase in bodyweight. Blood plasma is a heat sink and a reservoir for sweat. As blood circulates through working muscles it absorbs heat. Skin blood flow also increases as a response to increasing core temperature so the heat can be transferred to the environment. While near the skin, some of the fluid in blood plasma is drawn into intercellular space to replenish interstitial fluid that was drawn into sweat glands and secreted onto the skin.

Increased muscle mass:

Yes, you may have gained muscle mass, and that is a good thing! When we start working with new athletes, there is often some rapid weight loss (10-15 pounds) and then weight stabilizes but body composition continues to improve. This can happen with experienced athletes as well, and depending on the athlete you may be getting leaner and gaining enough muscle mass to more than offset the lost fat weight. And yes, older athletes can gain muscle mass. You may not gain as much as younger athletes or as quickly, but older muscles still respond to stimulus the same basic way younger ones do.

Causes of unwanted midseason weight gain

Before you get too excited about the section above, plasma volume and glycogen storage account for the minor day-to-day fluctuations in your weight, which are hopefully only about 1%. And unless you are specifically training to gain muscle mass, you’re not going to gain 5 pounds of muscle in 2-4 weeks. If your weight has increased more than 3% (+5 pounds for a 165-pound athlete) this summer, something may be amiss.

Here are a few reasons athletes inadvertently gain weight while training

Failure to apply progression principle

As you improve your fitness you have to increase your training workload in order to continue making progress. In training terminology this is known as the Principle of Progression. For time-crunched athletes, training time or volume is typically constant, meaning you can’t just add more training time to increase workload. That means you need to examine your training intensities to see if it’s time to increase them. Running a 9-minute mile may have been your lactate threshold pace earlier in the spring, but now that you have improved your fitness you may need to run 8:30 pace to achieve the appropriate workload. If your lactate threshold power on the bike was 250 watts in the spring, that may now be more appropriate as your Tempo power and your power for lactate threshold intervals may need to increase to 265-275 watts. In a variety of ways your body gets better at squeezing performance out of calories, so if you are training with outdated intensities you may not be burning as many calories as you think you are.

Caloric overcompensation

As training workload increases many athlete increase caloric consumption more than necessary. Sometimes this results from a work-and-reward mentality: “I trained hard, so I can eat whatever I want.” Other times it results from a misconception about how much food is required to optimize post-workout recovery and/or fuel up for an upcoming workout.

To avoid caloric overcompensation during the summer I recommend focusing any increase in caloric intake immediately before, during, and after training. This means adding a small snack in the hour before training, consuming some additional calories while you’re training, or adding some recovery-specific calories in the 60 minutes post workout. These small additions are typically 100-150 calories each (a bottle of sports drink/recovery drink, a bar, or a gel). It is harder to gorge on these items and end up adding 1000 calories to your daily intake.

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Social drinking/eating

Community is one of the biggest draws of endurance sports, and although we may spend long hours by ourselves training through the winter we do so – in part – so we can enjoy our sports together during the summer! Many of these get togethers include mid-ride café stops and post-workout beers and meals. I am not suggesting you skip these social occasions. They are one of the best parts of being an endurance athlete. But you do have to recognize these social occasions can contribute to in-season weight gain.

Poor recovery habits

Of all the reasons athletes may gain weight during the summer, this is the most serious and detrimental. Training leads to inflammation. That’s normal and an essential part of adapting to training stress. However, your recovery habits can mean the difference between minor inflammation that goes away and continual inflammation that leads to weight gain. Seemingly inexplicable weight gain is one of the signs we look for in athletes who may be chronically under-recovered.

Athletes who are not adequately recovering from exercise and lifestyle stress often have elevated levels of the stress hormone cortisol. Chronically elevated cortisol levels have been associated with sugar and junk/comfort food cravings, as well as increased fat storage. If you are gaining weight and have been training hard, it may be worthwhile examining whether your food choices and eating habits have also changed recently.

What NOT to do if you’re gaining midseason weight

Counteracting midseason weight gain is typically a matter of making sure your caloric intake is aligned with your expenditure (avoiding overcompensation or excessive social consumption) and focusing on improving recovery strategies. What you DON’T want to do is increase training workload even higher in an effort to lose the weight! If your training workload is appropriate for improving performance, it is most likely higher in the summer than during any other period of the year. Increasing it further for the purpose of creating a caloric deficit is likely to diminish your performance gains and be insufficient to produce much weight loss.

The other thing to consider is that having fun during the summer season may be worth gaining a few pounds. Most of us aren’t making a living based on our cycling, running, or triathlon performance. If your performance is satisfactory and you’re enjoying your engagement with your sporting community, then a few pounds shouldn’t get in the way.

Chris Carmichael
CEO/Head Coach of CTS

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Comments 4

  1. Excellent & very well-informed piece, Chris.

    I have the opposite problem (?): midseason weight loss. I make sure I hit all my macros, calories, and refuel and hydrate obsessively. I live in a very hot climate & often train in 90-100 F heat (I methodically acclimate for this). Midseason, I train 10-12 hrs. per week. I do get back to my usual weight during recovery weeks.

    My form improves by all measures, regardless of weight loss. All I notice is subcutaneous fat loss. Could I improve my performance by maintaining my weight? If I were a climber, I’d be excited, but I’m not.

    Thanks very much!

  2. This might explain the mystery 2 kilo gain. Fortunately, I have resisted the drop at all costs because that just makes me more hungry. One thing I am doing is mixing up.the rides. H
    I.have less time for endurance rides, but the hills are calling. That helps with boredom and helps with the time crunch. Great words on overtraining. Two days of rest per week and the addition of yoga.

  3. Excellent piece. Weight is a complicated subject. Intensity always sheds it on me while LSD riding always makes me gain. Ps I shredded 2500 cals on a 5 hour mtb ride yest, intook 2500 cals and gained 2 lbs…..

    1. This was a great article, that gave me more insight as to why I might be gaining weight during the midseason. As athletes we do tend to eat a little to much after we do a really long or hard workout. However, if we just remember to recover properly we might be able to slow weight gain down. I can understand how hard it is when you are a time crunch athlete, with family and work there seems to never be enough time to do a workout let alone recover.

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