One of the biggest mistakes people make is that they fall into a routine and stick to the same workouts. While effective in the beginning, eventually the body gets used to them and no longer finds them challenging. You want to constantly shock your body, get your heart rate going and burn fat. Even if you only have 30 minutes (that’s the least amount of time you should spend at it. Anything less is not really worth your time, you’ll barely get your metabolism going), you want to make the most of it.
Don’t get too hung up on numbers. While you want to maximize your calorie burn, it is also about the power of your workout. Inevitably you will burn more doing cardio than you will in a more strength/circuit style class or workout but you will also build more muscle in the latter which is crucial to your weight loss, since muscle burns twice as much fat.
You want to have at least two cardio and 3 to 4 strength/circuit workouts per week. I know it’s not always easy to make it part of your everyday life, but if you want it bad enough, you’ll make time. I’m not trying to sound like an asshole, it is the truth. Cardio will help you get the fat off but will not help you tighten up and get all those definitions we all all love. With cardio, try to work at 75-80% of your max heart rate. You can get that number by subtracting your age from 220 to get your maximum heart rate, then just do the math from there. Most cardio machines have sensor. While they are not completely accurate (they tend to show a lower value), they will give you a rough estimate.
You also want to up the ante. If you lifed 15lbs, the next time, or next rep if you’re doing circuits, go for 20. Also once you get heavier weights, decrease the number of reps so you don’t destroy your muscle. Say if you did 15 chest flies with a bridge on a body ball using 15 lbs weights, when you go to 25 lbs, only do 10 or 12. You want it to feel like work, you want to come out of that gym sweating with our legs turning to jello. Don’t overdo it though. If it really hurts, stop. No point in getting injured.
Don’t forget to fuel your body. Make sure you eat something no sooner than an hour but no later than 30-45 minutes before and no sooner than 30 minutes after a workout. For your pre-workout meal try to make sure you get both carbs and protein; for post workout try to make it mostly animal protein to help your body patch up the damage (normal muscle tear) caused by the workout. If I’m on the go, I usually have a protein bar with me for that very purpose. Stay clear from high calorie, high sugar ones. My personal favorites are Think thin and Power crunch. They both have 5 to 0g of sugar. Think Think tends to be a little higher in calories, but they do have reasonable numbers. Now that you know all that, what are you waiting for? Hit the deck!