A few things influence how many calories you burn when swimming: Bodyweight: A larger individual will burn more calories naturally than a smaller person. Intensity of Workout: The quicker you swim, the more calories you burn. Workout Duration: The longer you exercise, the more calories you burn. Swimming is a low-intensity activity. You can increase the intensity of your workout by adding some additional exercises to your routine or by going faster. Eating while you're swimming is fine as long as it doesn't affect your performance. The best thing you can do for your body in terms of nutrition is eat regularly and consume foods that are high in protein and carbohydrates. Swimming requires lots of energy, so make sure you refuel after each session. Some examples of effective post-swim meals include: Whole-wheat pasta with tomato sauce, chicken breast, salmon, or vegetables like peas or corn It's important to remember that you can't outrun your appetite. If you feel like you're hungry during your workout, then eat something before you begin. Also, try not to skip meals when you're trying to lose weight. This will only cause you to crave more fatty foods as well as other harmful substances such as caffeine which act as stimulants that will keep you alert even when you should be sleeping.