Swimming , my favorite sport

Assuming you can perform each stroke for the same amount of time, the butterfly will be your best bet for both fat loss and muscle building. This is because you are burning the greatest number of calories per hour while performing it, making it an efficient way to create the caloric deficit needed for fat loss. It is also the stroke that takes the most muscular power, therefore giving your body the best total strength-training workout.

If building muscle is your primary goal, you may wish to perform this stroke at the highest intensity possible, but for a shorter period of time. That way, you won't expend as many calories (since you need to be in a surplus to build muscle), but you will push yourself hard enough to stimulate muscle growth.

important considerations

Since you are performing this workout in water, there are a few additional considerations. One of the most important aspects of swimming is learning to regulate your breathing; because your head is only above the water at certain moments, you must adapt your breathing to each stroke. Some people will need to practice this before jumping into a workout. If you haven't mastered your breathing rhythm, you will find it difficult to push yourself hard enough to derive benefits, as your muscles need oxygen to perform properly.

It is also critical for you to master the type of stroke you plan on using before trying to swim laps. If you aren't performing it correctly, you will be inefficient and will tire out much more quickly than if you were using the proper technique. If your body is moving in rhythm with a fluid series of actions, you will be able to focus on pushing yourself to get your heart rate up, thus improving your workout.

benefits of swimming

There are many reasons to take your next workout to the pool. First, it is a great cardiovascular exercise. If you push yourself hard enough, swimming can be comparable to -- if not more intense than -- running. Since you use both your upper and lower body to propel yourself through the water, you engage more muscles and burn more calories than with running (during which the upper body doesn't work that much).

In addition, swimming gives you a great strengthening workout. The day after your first serious session in the pool, your upper body will likely be very sore. You will be using muscles in ways you don't normally use them, which will serve to strengthen your whole shoulder girdle as well as your back muscles (particularly your Latissimus Dorsi muscle).

Finally, many people find swimming to be a very good way to relieve stress. It allows you to clear your head so you are not only getting physical benefits, but psychological ones as well.

It's not always a fat loss issue , some people have to gain weight

1. Keep in mind your goal is to gain weight while building muscle mass. If you just start eating a lot more and you don’t exercise, all you’ll end up with is unhealthy fat gain.
2. Concentrate on adding protein to your diet. Protein is what makes your muscles grow, and muscles weighs more than fat; the more muscle mass you have, the more you will weigh. Get the maximum amount of protein that your body can use in a day—about 1 gram for every pound you weigh. If you currently weigh 170 pounds (77.27 kg), add at least 170 grams of protein to your daily diet.
3. Figure out how many more calories per day you need. Use a quick online calculator to find your resting metabolic rate (RMR) or use the formula below:
   • Multiply your weight in pounds or kilos by 12.
   • Multiply that figure by 1.6 to get your basic resting metabolic rate (how many calories you burn without exercising at all)
   • Multiply by 5 the number of minutes you spend each week on lifting weights.
   • Multiply by 8 the number of minutes you spend each week on aerobic exercise (running, cycling, etc.)
   • Add together the total minutes you spend on each type of exercise each week and divide the total by 7. Add this number plus 500 to your basic metabolic rate. The result will tell you how many calories you need every day to gain 1 pound (.45 kg) a week.
4. 4
   Increase the amount of time you spend on strength training. Concentrate on building up your largest muscle groups. For best results, do 3 sets of 12 repetitions for each type of strength training.
   • Squats
   • Pull ups
   • Bench presses
   • Dead lifts
5. Give your muscles time to recover from strength training exercises. Muscles grow when you are at rest, which is why it is advised to rest for 24 hours after a day of strength training. Your muscles also need some recovery time while you are engaged in strength training; be sure to rest for 1 or 2 minutes between sets of repetitive sets.
6. Have an energy shake immediately after each workout. According to a study carried out at the University of Birmingham,UK, energy shakes will help you improve your endurance while exercising. Carbohydrates increase the insulin level in your body, and that will slow down the rate that your body breaks down protein—the protein you need for muscle building. Have a banana, a handful of dried fruit or a sports energy shake immediately after you work out.
7. Don’t abandon your high intensity workouts. You do burn more calories during aerobic exercise, but aerobic exercise stimulates your muscles in ways that strength training does not. Aerobic exercise increases your cardiovascular health, and it will keep you from getting fatigued when you are doing your strength training.
8. Eat six meals a day. It’s important to keep your body supplied with energy and nutrition throughout the day. Some of your meals can be in the form of high calorie, healthy snacks, such as nuts, avocados and protein shakes.
9. Get 8 hours of sleep every night. If your body doesn’t get enough rest every night, you won’t have enough energy to exercise.
10. Don’t get stuck in a rut. Your body has the ability to adapt quickly, so if you don’t alter your exercise routing occasionally, you will hit a plateau. Once a week, change up your routine. You can increase or decrease the number of reps or sets, or simply change the order in which you normally do your routine.

First of all , you should have a nice body to exercise ( losing weight )

Sure, you can not  lose weight in one day but if you folow these steps you will notice the difference in one week . There are plenty of fad diets that work to shed pounds rapidly -- while leaving you feeling hungry and deprived. But what good is losing weight only to regain it? To keep pounds off permanently, it's best to lose weight slowly. And many experts say you can do that without going on a "diet." Instead, the key is making simple tweaks to your lifestyle.
One pound of fat -- is equal to 3,500 calories.  By shaving 500 calories a day through dietary and exercise modifications, you can lose about a pound a week. If you only need to maintain your current weight, shaving 100 calories a day is enough to avoid the extra 1-2 pounds most adults gain each year.
Adopt one or more of these simple, painless strategies to help lose weight without going on a "diet":

1. Eat Breakfast Every Day. One habit that's common to many people who have lost weight and kept it off is eating breakfast every day. "Many people think skipping breakfast is a great way to cut calories, but they usually end up eating more throughout the day, says Elizabeth Ward, MS, RD, author of The Pocket Idiot's Guide to the New Food Pyramids.  "Studies show people who eat breakfast have lower BMIs than breakfast-skippers and perform better, whether at school or in the boardroom." Try a bowl of whole-grain cereal topped with fruit and low-fat dairy for a quick and nutritious start to your day.
2. Close the Kitchen at Night. Establish a time when you will stop eating so you won't give in to the late-night munchies or mindless snacking while watching television. "Have a cup of tea, suck on a piece of hard candy or enjoy a small bowl of light ice cream or frozen yogurt if you want something sweet after dinner, but then brush your teeth so you will be less likely to eat or drink anything else," suggests Elaine Magee, MPH, RD, WebMD's "Recipe Doctor" and the author of Comfort Food Makeovers.
3. Choose Liquid Calories Wisely. Sweetened drinks pile on the calories, but don't reduce hunger like solid foods do.  Satisfy your thirst with water, sparkling water with citrus, skim or low-fat milk, or small portions of 100% fruit juice. Try a glass of nutritious and low-calorie vegetable juice to hold you over if you get hungry between meals. Be careful of alcohol calories, which add up quickly.  If you tend to drink a glass or two of wine or a cocktail on most days, limiting alcohol to the weekends can be a huge calorie saver.
4. Eat More Produce.  Eating lots of low-calorie, high-volume fruits and vegetables crowds out other foods that are higher in fat and calories. Move the meat off the center of your plate and pile on the vegetables. Or try starting lunch or dinner with a vegetable salad or bowl of broth-based soup, suggests Barbara Rolls, PhD, author of The Volumetrics Eating Plan. The U.S. government's 2005 Dietary Guidelines suggest that adults get 7-13 cups of produce daily. Ward says that's not really so difficult: "Stock your kitchen with plenty of fruits and vegetables and at every meal and snack, include a few servings," she says. "Your diet will be enriched with vitamins, minerals, phytonutrients, fiber, and if you fill up on super-nutritious produce, you won't be reaching for the cookie jar." 
5. Go for the Grain.  By substituting whole grains for refined grains like white bread, cakes, cookies, and pretzels, you add much-needed fiber and will fill up faster so you're more likely to eat a reasonable portion. Choose whole-wheat breads and pastas, brown rice, bran flakes, popcorn, and whole-rye crackers. 
6. Control Your Environments.  Another simple strategy to help cut calories is to control your environment -- everything from stocking your kitchen with lots of healthy options to choosing the right restaurants. That means avoiding the temptation by staying away from all-you-can-eat restaurants.  And when it comes to parties, "eat a healthy snack before so you won't be starving, and be selective when you fill your plate at the buffet," suggests Ward.  Before going back for more food, wait at least 15 minutes and have a big glass of water.
7. Trim Portions. If you did nothing else but reduce your portions by 10%-20%, you would lose weight. Most of the portions served both in restaurants and at home are bigger than you need.  Pull out the measuring cups to get a handle on your usual portion sizes, and work on paring them down.  Get instant portion control by using small bowls, plates, and cups, says Brian Wansink, PhD, author of Mindless Eating. You won't feel deprived because the food will look plentiful on dainty dishware.
8. Add More Steps. Get yourself a pedometer and gradually add more steps until you reach 10,000 per day. Throughout the day, do whatever you can to be more active -- pace while you talk on the phone, take the dog out for an extra walk, and march in place during television commercials.  Having a pedometer serves as a constant motivator and reminder.
9. Have Protein at Every Meal and Snack.  Adding a source of lean or low-fat protein to each meal and snack will help keep you feeling full longer so you're less likely to overeat. Try low-fat yogurt, small portion of nuts, peanut butter, eggs, beans, or lean meats. Experts also recommend eating small, frequent meals and snacks (every 3-4 hours), to keep your blood sugar levels steady and to avoid overindulging.
10. Switch to Lighter Alternatives. Whenever you can, use the low-fat versions of salad dressings, mayonnaise, dairy products, and other products.  "You can trim calories effortlessly if you use low-fat and lighter products, and if the product is mixed in with other ingredients, no one will ever notice," says Magee. More smart substitutions: Use salsa or hummus as a dip; spread sandwiches with mustard instead of mayo; eat plain roasted sweet potatoes instead of loaded white potatoes; use skim milk instead of cream in your coffee; hold the cheese on sandwiches; and use a little vinaigrette on your salad instead of piling on the creamy dressing.