Weight Gain After Cardio: What You Can Do About It.

Hey Davey,

I have been doing a lot of cardio recently but have found that in the past four days I weigh four pounds more than usual? Is it water weight? Is it new muscle? What’s going on!


Hey Jerry,

First things first, four pounds is nothing to fret about. I think I’ve taken shits that are bigger than that (too much information?) – so keep in mind your body’s own internal biological workings. Ensure that you are weighing yourself at the same time of day and at the same point in your routine for more accurate results; some people report body weight fluctuations of as much as six pounds during the course of a single day.

If the four pounds aren’t the result of normal flucuations – and instead, indicative of a true trend (i.e., you gain another four pounds next week) – it’s impossible for me to say whether it’s water, fat or muscle. But in actuality, it could be any or all of the three.

While people generally associate cardiovascular exercise with weight loss – it’s not always the case. Long cardio sessions can result in the breakdown of muscle – which slows the metabolism and often results in unwanted weight gain. For the best results, limit your cardio exercise to 45 minutes or less. Many of my cardio sessions are only 15 minutes long (but very intense). It’s a matter of quality – not quantity!

If, in addition to your cardio workouts, you are engaged in strength training (i.e., lifting weights, weight machines, etc.), then it’s possible that your additional mass is muscle. Muscle is very dense and heavy. If you are looking to release extra body fat, adding muscle is one of the best ways to do it. To know if your gains are muscle, you’ll have to look beyond the scale. Instead, try alternative ways to quantify your progress – such as measuring your waist. If you lose inches off of your waist and yet gain pounds, it’s a good clue that your gain is the result of muscle. And that would be a very good thing!

Lastly, your weight could be the result of water retention. To eliminate water weight, eat a healthy, balanced diet that is low in sodium. Moreover, you need to drink water to lose water – so stay hydrated. If you are not drinking enough water, your body will go into “drought mode” and retain any and all water like a camel. Not drinking enough water, by the way, also slows down your body’s metabolism and can result in unwanted weight gains.

Bottom line: Ensure that you are limiting your cardio workouts to 45 minutes (or less), are participating in strength training workouts and are staying hydrated.

I hope that helps!


About Davey Wavey

Davey Wavey is a certified personal trainer and YouTube sensation with more than 250 million video views. For Davey's fitness tips and secrets, sign up for his free monthly newsletter - or download any of his affordable and effective workout programs.


  1. Great advice. I know you said this, but I can’t stress this enough to people. Weight should only be used as a very rough gauge of progress. On the scale of measuring your progress, it’s way down there. And I’m one of those that have seen fluctuation of up to 6 pounds in one day, so don’t stress it.

    As an extra question to Davey (or anyone that knows) You say that excessive cardio routines will break down muscle. What about very low intensity routines? So let’s say that I do 30 minutes of bike a pretty good pace, then slow down to a very casual stroll on the bike (or maybe a walk) for another hour, for additional calorie burn. My thought is that this will not break down the muscle like intense activity, but what do you say?

    • Hey Zak,

      if you have low intensity workouts where you’re moving but feel relaxed and where you can easily talk to someone, than you are not in a Cardio mode but in the fat burning range. (That is to say in the aerobic traning) There this effect of muscle breakdown should not occure.
      sure you burn calories slower than when you do excessive cardio (which really bursts your metabolism and burnes a lot of energy) but you can basically go on for as long as you want. it’s not so much more different then when you go for a day of hiking or skeeing or something alike.

      It is called the fat burning mode because if you train at high heartrates your body needs to use the easily accessible energy. nut if you train with a low heart rate it can use the energy that takes a little more effort to break it down and this is your fat. Also fat can only efficiently be burned in aerobic training, but I guess that’s something for Davey to explain. he finds better words ๐Ÿ™‚

      in any case, cario training is a very good thing and it also helps burning fat in the long term. it makes you fitter in general, bursts your metabolism (which in turn is good for fat burning too), and what I like best about it, it makes you feel terribly good! but there is also nothing to say about your slower workout for additional calorie loss. only one thing you should bear in mind! your calorie deficit must not exceed a certain level a day. for if the deficit is too big, i.e. you’re burning too many calories without a sufficient calorie intake, your body will go into starvation mode and extract every little bit of energy it can get from anything you eat and drink and will store it quicker than normaly…. I think Davey gave tips on that one too already.
      so yeah. low intensity training is good too and should not break down muscles ๐Ÿ™‚

      • ups I meant
        “hey Joe”
        that is what happens if the browser displays the wrong post ๐Ÿ˜€

  2. Thanks for this post today! My partner and I are both in a marathon training program, and finally, at the end of week 8, I feel like I am losing instead of gaining. All of the water that we have been drinking was good for our long runs, but afterwards I would feel and look bloated. Yesterday was the first time I put on my skinnys and noticed that they were no longer skinny. Give it time!

  3. I watch the tape measure on my waist, not the scale!

  4. I am a certified personal trainer and I can say with certainty and experience that many people will absolutely gain bodyfat as a result of long aerobic sessions done at a moderate intensity. Marathon run training is probably the biggest culprit when it comes to this example. If you go to watch a marathon you see thousands of runners who have big, flabby bodies and old t-shirts from previous marathons yet they will be crossing the finish line with good times (sub-4 hours). The body often responds to endurance training by storing bodyfat and increasing appetite.