If I want to lose fat quickly, should I do as much cardio as possible?
Actually, no. The amazing and often frustrating thing about the human body is it adapts. If you start with a lot of cardio, you will lose fat. However, once your body adapts to this amount of work and fat loss slows, you will have to do more. The concern here is that you will need to eventually do so much cardio that fitting it into your lifestyle may be difficult. There are other components of a cardiorespiratory exercise program that can be manipulated other than time. For example the mode, frequency or intensity.

I do not do cardio because I hear that it will burn muscle. Is this true?
No. To use a significant amount of muscle protein as an energy source you would have to be eating very few calories or exercising for a very long period of time. During the typical cardio bout, muscle glycogen and fatty acids from fat stores provide the majority of energy.

Which is best for burning fat – high-intensity or low-intensity cardio?
Losing fat is a matter of consuming fewer calories than those that are expended. So, whatever allows one to burn more calories is preferable. Performing cardio at a higher intensity (based upon abilities) will allow one to burn more calories in less time. Additionally, high-intensity cardiorespiratory exercise has been shown to increase metabolic rate for a longer period post exercise (EPOC) than lower-intensity cardio.

I read that doing cardio first thing in the morning on an empty stomach is the best way to lose fat. What do you think?
Well, it is a way, but not necessarily the best way. When you awaken, your body is in a fasting metabolic state and burning fewer calories per unit of time than usual. Consuming some food will perk your metabolic rate up (hence, the term "breakfast" – breaking the fast). Additionally, glycogen stores are depleted by as much as 80%. This will adversely affect your ability to work out at a high intensity and may cause weakness and dizziness and lead to early fatigue.

If meal preparation time is an issue, the use of a meal replacement drink can be helpful.

Will using the stairmaster make my legs and butt bigger?
No. If the exercise is done at the appropriate intensity to make it aerobic, the stimulus will not be sufficient to cause muscle hypertrophy (growth). Often what happens is that when one begins an exercise program, their hunger may increase or they may begin justifying additional food – the "I earned this" syndrome. If caloric intake exceeds expenditure, then fat stores can increase. This may occur on the thighs and buttocks.

Should I perform cardio before or after my resistance training?
For the majority of people, it makes no difference and becomes a matter of preference. If one’s goal is maximum anaerobic power and strength, then it may be advisable to limit the amount of high intensity cardio done prior to resistance training, sparing glycogen for the heavy stuff. If this were, indeed, the goal, one may not even be doing cardio and, realistically, glycogen usage would not be that great.

I take a 20-minute ab class several times a week but I don’t seem to be making my midsection more defined. What’s wrong?
Although doing ab classes increases the amount of calories you burn in a day, where fat comes from and when is beyond our control. To lose the body fat that covers your abdominal muscles, you must be in a caloric deficit. Performing cardirespiratory exercise will increase the amount of calories burned and will tap into the body’s fat stores to provide the missing calories. Ultimately, fat stores in the abdominal region can and will contribute to this. Depending on your lifestyle and genetic factors, this may happen sooner or later.

Which piece of cardio is the best for burning fat?
All are effective for increasing caloric expenditure and aiding in fat loss. The intensity at which you perform the exercise is a better aspect to focus on. Performing aerobic exercise at a higher intensity will allow you to burn more calories per unit of time than if the exercise were performed at a lower intensity.

If possible, change the mode of cardio you do every few weeks. This will help prevent the reduction in energy expenditure that accompanies an adaptation to a given mode. Keeping the exercise unaccustomed leads to higher energy expenditure during the activity.

The display on the cardio machine I use says I burn a lot of calories during my workout. Is it accurate?
Most likely not. There are many factors that influence the number of calories that one expends during exercise, such as muscle mass, current physical condition and even genetic factors. The number displayed on the equipment tends to be optimistic.