Doing 20 repetitions of squats can meet the cardiovascular and the resistance requirements for a complete weight loss workout. Although not as effective at either as more specialized workouts, it can provide a quick fix for those with crowded schedules.
A set of 20 squats works out the largest muscles of the body, requiring you to immediately take in extra oxygen to feed them. This makes this a better cardiovascular workout than other fast-twitch calisthenics and weight routines, says Oregon-based fitness coach Ben Cohn. It gets the heart pumping and the calories burning that much faster. Likewise, as a body weight exercise or as a weight workout, the muscle growth helps to boost your metabolism.
You can do your squats with no weights, holding dumb bells or with a barbell across your shoulders. In all three cases, you should take care to protect your back and knees. According to Stuart McRoberts in "Brawn," you should stand with your feet shoulder width apart. Your feet should point out at 90 degrees from one another, both pointing 45 degrees out from the direction you're facing. This will keep the knees aligned and protected. Although you bend at the hips and knees, you should keep your back straight but not locked. One good practice is to keep your eyes on the ceiling as you go through the motion. This naturally keeps your back aligned.
A set of 20 squats takes about 30 seconds at a moderate pace. According to fitness resource website HealthStatus, this will burn about 3 calories without weights and 4 with weights. Although this isn't a lot of calories on its own, it's an impressive burn considering the brief duration. Note that your caloric burn will go up if you are heavier than average, or down if you are lighter than average.
Because your body weight — and any additional weight — resists your attempts to stand during a squat, the exercise builds muscle in your glutes, thighs, hamstrings and back. In his landmark book "Eat, Drink and Be Healthy," Harvard nutritionist Walter Willett writes that bodies with more muscle burn more calories in all activities. This means that the more squats you do, the more calories you will burn with each subsequent workout.
Advantages of 20-squat sets for weight loss include simplicity and portability. Squats are easy to learn and require no props, meaning you can knock out a set any time you have a spare minute. This defeats one common barrier to exercise: finding the time and the facilities.
One con of 20-squat sets for weight loss is that the individual sets burn few calories. At 3,500 calories per pound, you'd need to do 1,750 sets to burn a pound worth of calories. A second disadvantage is that squats done wrong can cause serious problems in the back and joints. Cohn advises getting trained in squats by a qualified professional before committing to a course for losing weight.