Is it true that aerobic exercise burns fat faster than other types of exercise?
Aerobic exercise is the only way for your body to burn fat directly. Anaerobic exercise uses only carbohydrtes and fats. Fat is releaed from fat cells after about 20 minutes of aerobic exercise. At that point, your body shifts from using mainly carbohydrates as fuel to using more fats. You need to keep in mind however, that when you eat, you replenish both carbohydrates and fats.
As soon as you reach the point of having consumed an excess of calories, your body begins to store those calories as fat. If you eat after an activity that utilizes more fats than carbohydrates, you fill up your carbohydrate stores faster, thereby creating a situation where the excess calories are converted to fat anyway. Therefore you have not altered your body’s overall caloric balance. You lose weight when you expend more calories than you consume, not because you burn fat when you work out.
Does aerobic exercise accelerate weight loss when combined with a low-calorie diet?
In general, participation in moderate amounts of aerobic exercise combined with dieting does little to accelerate weight loss. In order for aerobic exercise to have a significant effect on weight loss, regular workouts (i.e at least 4 times per week) need to be performed at a high level of intensity (i.e. greater than 80% of maximal aerobic capacity) for at least 60 minutes duration per workout. Most experts agree however, that moderate amounts of aerobic exercise performed without changing ones diet, will have little impact in promoting weight loss.
Why does aerobic exercise have little effect in accelerating weight loss when combined with a low calorie diet?
There are several possible reasons for why this happens. Among the most common are as follows:
Many overweight/obese individuals are unable to perform high amounts of exercise with out subjecting their bodies to an undue level of orthopedic stress, which can lead to injuries. High amounts of exercise are needed to promote weight loss and therefore the risk of injury to these types of individuals outweighs the benefits that can be gained safely.
The net caloric expenditure of moderate aerobic exercise is relatively small. The net caloric cost of exercise is equal to the number of calories expended during an exercise session that are used beyond the number of calories expended by an individual resting metabolism (RMR), and any other activities that the individual might have been engaged in had they not been exercising.
For example: the net caloric expenditure of a 4 mile walk in one hour completed by a person weighing 150lbs. Gross caloric expenditure for a 4 mile walk = 280 calories, resting metabolic rate for 1 hour – 70 calories. Caloric expenditure for mild physical activity had the person not been walking 4 miles -70 calories. Net caloric expenditure of a 4 mile walk 140 calories.
Some individuals who exercise tend to reward themselves by reting and relaxing after their workouts are over. As a result, the net change in their total 24 caloric expenditure levels may be unchanged.
Does aerobic exercise have a positive effect on the reduction in resting metabolism associated with dieting?
Current research suggest that aerobic exercise training does not otherwise diminish the usual 10-20% diet induced reduction in RMR. In facr the results of some studies indicate that combining aerobic exercise with a very low calorie diet (less than 1000 per day) stimulates the boby to save energy thereby signaling the body to initiate the process of decreasing the RMR.
Does aerobic exercise counter the decrease in lean muscle mass associate with dieting?
The combination of a moderate intensity aerobic exercise program with a low calorie diet does little to protect lean muscle mass during weight loss. During weight loss the percentage of weight lost as lean muscle mass increases in direct proportion to the magnitude of the coloric deficit encountered by the body. As a result of rigourous fasting, the total body weight that is lost is approximately 50% fat and 50% lean muscle mass. During a very low calorie diet but with adequate protein intake, the proportions improve to 75% fat and 25% lean muscle mass. During a low calorie diet (1200 – 1500 calories per day) the proportions improve even more to 90% fat and only 10% lean muscle mass. Moderate intensity aerobic exercise on the other hand has been found to have a very limited effect on these body composition proportions. Resistance training during weight loss, however, has been shown to provide a sufficient stimulus to offer protection against the loss of lean muscle mass during sensible dieting.
If aerobic exercise does not help me lose weight faster, then why should I do it at all?
Despite its limitiations with regard to promoting weight loss, exercising aerobically provides several important health benefits. Among the major benefits of aerobic exercise for overweight/obsese individuals are as follows:
Improved aerobic capacity .
Reduced risk of developing obesity related diseases such as diabetes, coronary heart disease and hypertension
Improved blood lipid lipoprotein profile specifically decreased triglycerides and increased HDL-C
Improved psychological status, increased self esteem, general well being, decreased anxiety and depression
Enhanced long term weight management
Regular exercise is the most powerful predictor of long term weight loss success. It helps individuals not only lose weight but keep it off.
Is there a quick and easy way to lose weight?
No, almost all diets share at least one common trait, eventually they do not work. To lose weight and keep it off, you must be willing to incorporate permanent changes in both your eating and physical habits. In other words a ‘lifestyle’ change.
