Many people think they can start swimming and those extra pounds will start melting off instantly. We’re sorry to be the bearers of bad news, but that’s just not the case. Sometimes, your swimming routine can cause you to gain some weight! 

While your individual body composition and goals are just that – individual – we want to break down a few reasons you may put on some extra pounds when you start swimming regularly. And don’t worry, it’s not all bad!

Why Swimming is a Good Workout

Swimming is one of the best workouts out there. It’s accessible for people of a variety of ages and abilities, and is a great option for cross-training or a primary workout program. Here’s why:

  • Added Resistance: When you swim, you’re actively working against the water. Water is 800 times more dense than air, which makes for a good challenge that burns calories!
  • Total Body Workout: Swimming works nearly every muscle in your body. You just don’t challenge your body the same way when you run or cycle.
  • Restricted Breathing: Swimming forces you to maintain a strict breathing pattern, which can be tough, and pushes your heart rate higher! You can play around with different breathing patterns to challenge yourself even more.

Why Some People Gain Weight Swimming

It’s important to note that not everyone gains weight swimming, and not everyone loses weight. However, if you do find that you’re gaining weight even after staying consistent with your training, this may be why:

You Get Hungry

Related: What Swimmers Should Eat Before, During and After Swimming

If you’re a swimmer, you’re probably very familiar with post-swim hunger! 

While swimming does burn a lot of calories, you may be overestimating the amount of calories you burn during each workout. As a result, you may overeat and put your body in a calorie surplus! This can cause you to gain weight if maintained for a long period of time.

To help curb your hunger, make sure you’re fueling properly throughout the day, and have a good snack before your workout. 

Swimming Isn’t Weight Bearing

Swimming is a great low impact activity. Due to the weightless nature of the sport, you will burn fewer calories than you would during a run or other land-based workout. 

If weight loss is a major goal for you, swimming can still be a good fit. You will just need to approach your training slightly differently. Try our Beginner Weight Loss Training Plan to get started.

Water Regulates Your Body Temperature

If you swim in a colder pool, the water helps to keep your body temperature under control as you start to push yourself during hard workouts. Most pools are likely between 79 and 82 degrees Fahrenheit. This means that your body does not have to expend as much energy to cool you down as it would during a run or gym workout.

Related: How to Lose Weight Swimming

You still sweat while in the pool, so make sure to drink plenty of water!

If your pool is too hot, your body can overheat, which can be dangerous. Be sure to monitor how you’re feeling and take extra rest if needed.

Increase in Muscle Mass

When you start swimming regularly, you’ll build muscle in areas you weren’t using as much before, like your shoulders, lats, back and core. 

As they say, muscle weighs more than fat. It’s common to see the scale increase when you lose body fat and gain muscle. More muscle helps you avoid injuries and swim faster…both good things!

If you’re already pretty muscular, you may not gain too much new muscle, but your body will start to retain more water as your training ramps up, which results in a small weight gain.

How to Burn More Calories While You Swim

Related: How Many Calories Does Swimming Burn?

If weight loss is a priority for you, try mixing up these variables to increase the effectiveness of your swim workouts. 

  • Frequency: It’s better to do four 30-minute swims per week than two one-hour swims. If you swim 3,000 meters in one hour, split the distance into four 1,500 meter sessions.
  • Distance: In general, swimming longer distances burns more calories.
  • Intensity: Incorporate speed work and shorter rest intervals to get your heart pumping!
  • Strokes: Swim all four strokes to challenge yourself in new ways. Many people find Individual Medley sets to be more challenging than freestyle sets.
  • Equipment: Mix in fins, paddles, a snorkel and more to vary your training and add extra resistance to build strength.

Calorie Torcher Swim Workout

Try this swim workout to burn calories and challenge your stamina! This Workout was created in the MySwimPro app, using personalized intervals for MySwimPro CEO Fares Ksebati. To get your own personalized Workouts, sign up for MySwimPro Coach!

  • Distance: 2,500 yards/meters
  • Duration: 55 minutes


  • 1×300 Freestyle @ 4:00 Easy
  • 4×50 Kick with fins @ 1:00
  • 6×50 IM Order x2 @ :50

Pre-Set (2x)

  • 4×25 3 Strokes 12 Kicks Drill @ :40 with fins, paddles & snorkel
  • 1×200 Freestyle @ 2:30 with snorkel

Main Set

  • 4×100 Freestyle @ 1:10 Descend
  • 8×50 Pull @ 1:30 Descend, with paddles & pull buoy

Cool Down

6×50 Freestyle @ 0:45 Ascend

For more swim workouts like this, download the MySwimPro app! Start a personalized Training Plan designed for your speed, goals and schedule.

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