Is swimming good for weight loss?

There is no doubt that swimming is an excellent exercise. It is low impact, great for your lungs & heart, reduces stress, improves strength and helps you stay flexible.

It also works a large number of muscles, and targets those that would otherwise be under-worked. In addition, people from all age groups can (and should) incorporate it into their lives.

But is swimming effective when you are trying to lose weight?

How weight loss works

Weight management is based on a simple equation: calories in – calories out.

“Calories in” represents the calories that you introduce into your body, via the food that you eat. “Calories out” represents the calories that your body burns naturally throughout the day, and when you exercise.

In order to lose weight, the result of this equation needs to be a negative number. This is known as being in a caloric deficit, which forces your body to use its fat stores as a source of energy.

A caloric deficit can be achieved via a combination of monitoring ones diet and exercising regularly.

There are a number of factors that determine how many calories you burn when you swim, including your current weight as well as the duration & intensity of the swim.

A short leisurely swim might burn only 100 calories, whereas a longer intense session could burn up to 700.

It can be difficult to estimate the exact number of calories that an individual burns when they swim, however the CDC approximates that a person who weighs 154 lb (70 kg) burns 255 calories when they swim freestyle at a slow pace for 30 minutes, and 510 calories in an hour.

This calculator also provides a similar estimate. The butterfly and front crawl are the most effective strokes and burn more calories than the breast and back strokes do.

In order for swimming to be effective when you are trying to lose weight, you need to ensure that you are swimming at an intensity that makes your heart beat vigorously and that you do so for a long enough period of time. Doing so will maximize calorie expenditure.

It might not be possible to swim at an intense pace right off the bat, especially if you are just starting out or haven’t swum in a while. However don’t let this discourage you. Start off slowly and gradually increase the intensity at which you swim. As long as you are consistent, you will get there soon enough.

It might even be beneficial to get a few swimming lessons from a professional, just to make sure your ‘form’ is correct. Training equipment such as boards and buoys can also be beneficial for beginners.

High intensity interval training (HIIT) would come in handy once your are confident that you can swim at a fast enough pace. This is a type of training that combines short bursts of intense activity followed by longer periods of the same activity at a more relaxing pace. It has been shown to help with fat burning and weight loss.

For example, this study involved 45 overweight women who either engaged in regular cardio or HIIT. The regular cardio group cycled for 40 minutes at a steady pace, whereas the HIIT group cycled for 20 minutes, switching between cycling “all out” for 8 seconds and then cycling at a slower pace for 12 seconds. The study found that the HIIT group ended up losing three times more body fat.

Even though the study involved cycling, HIIT can be practiced with many different cardiovascular activities, swimming included. An example of this would be to sprint for 1 lap and then recover during the next lap. As your stamina grows you can increase this to 2 sprint laps followed by 1 recovery lap.

There have also been some studies investigating how effective swimming is when it comes to weight loss. This study compared the effects of swimming vs walking on body weight, fitness, lipids, glucose and insulin in older women.

116 women aged between 50 and 70 who lead a sedentary life were randomly assigned to swimming or walking. They engaged in exercise of moderate intensity 3 times a week, for one year (the first 6 months were supervised and the next 6 were not). The results showed that swimming resulted in more weight loss than walking did.

Swimming makes you hungry!

Anyone who has swum for a lengthy and intense enough period will attest to the fact that swimming can leave you feeling famished. The exact reason for this is not known but it is thought to be because of the cool temperature of water in swimming pools.

A clear example of this is the Olympic swimmer Michael Phelps who would eat upwards of 10,000 calories per day (as a comparison, the average adult eats around 2,000) in order to have enough energy to fuel his training sessions.

Diet and exercise go hand in hand when losing weight. The last thing you would want to do is burn 500 calories in the pool and then end up eating 800 calories because you are so hungry. This is why it is important to keep an eye on your diet and make sure you are eating whole nutritious foods that are low in calories but filling at the same time.

For example, a chicken burger has around 600 calories, whereas a grilled chicken breast, baked sweet potato and cup of boiled vegetables has around 500 calories.

Not only does the second meal have fewer calories, it is also more nutritious and will leave you filling satisfied for longer, thereby making it less likely for you to overeat. After swimming, try to avoid calorie dense junk food and opt for natural wholesome food instead.

The number of calories that you should consume when trying to lose weight will depend on your age, gender, height, weight and how active you are.

You can use the calculator below to estimate what your calorie intake should be.

Gender Age Weight Switch to lbs Height Switch to feet and inches Activity Level

This calculator will never show a number below 1000 calories per day. Please speak to a qualified health professional before attempting to eat less than that.

For example, a 35 year old lady who weighs 75 kg (165 lb) is 180 cm tall (5 feet, 6 inches) and swims intensely 4 times a week would need to consume approximately 1900 calories to lose weight.

When trying to lose weight, it is a good idea to increase your protein intake because it has a high satiety, boosts metabolism and is required for muscle growth & repair. There are lots of protein rich foods available including eggs, fish, meat, beans, legumes, nuts, seeds and certain vegetables. Aiming for a protein intake of 25 – 30% of total daily calories would be ideal.

It is also important to drink plenty of pure water and stay well hydrated. It may seem impossible, but swimmers can suffer from dehydration. This is because you sweat profusely when you swim, especially in indoor swimming pools where the air and water are heated. Dehydration can negatively impact weight loss because thirst can be mistaken for hunger, thereby leading to overeating.

Another important thing to note is to be more concerned about your overall body composition than just your weight. This is because swimming builds muscle, and just like fat, muscle has mass. However a pound of muscle is much more compact than a pound of fat, so takes up less space in your body. Take a look at the body’s of professional swimmers and divers – despite the amount that they eat, they are all lean and toned, thanks to the muscle definition that they have.

It may be discouraging to swim for hours on end and then step on the scale and not notice a change. But don’t rely on the scale alone. Instead, get your body fat measured and take pictures of yourself. If after a month you notice that the number on the scale has not gone down much but your body fat has, and you can see visual changes when you look in the mirror and your clothes fit looser, this is definitely a step in the right direction.


Swimming can be highly beneficial for weight loss, so long as it is practiced correctly. If you are not going to be doing any other form of exercise, aim to swim 3 or 4 times a week at an intense pace for at least half an hour. Make sure you warm up and stretch before swimming, to minimize aches and sores the following day. It is also important that there is a lifeguard on duty when you swim.

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