The Science Behind Aerobics And Weight Loss

If there is a sure shot way to lose weight it definitely involves a lot of moving about and efforts. It is called exercise. When we say exercise it is more than just walking but then again it definitely doesn’t have to be lifting real heavy weights at the gym.

If you are thinking of something that will help you lose weight and not be strenuous then you can opt for aerobic exercise.

Aerobic means in the presence of oxygen. Aerobic exercise involves large muscle groups being used for long period of time and this in turn strengthens the heart.

The heart muscle becomes stronger and more efficient; a larger amount of blood can be pumped with each stroke. This in turn increases an individual’s stamina.

How does aerobic training cause fat loss?

When you are exercising, moving your muscles requires energy. Muscles derive energy from carbohydrate and fat. This requires oxygen.

Normally our heart beats at 60-80 beats per minute at rest. While exercising we require more oxygen so to provide that our heart beats faster.

aerobic image 1As we regularly practice aerobic exercise, our heart becomes stronger and pumps more blood with each beat. This leads to greater stroke volume which means that the heart doesn’t have to beat fast enough to meet the oxygen requirements of the exercise.

Eventually your muscle gets stronger and more efficient in utilizing this amount of oxygen which in turn translates into burning more fat.

Aerobic exercise is fueled by either carbohydrate or fats. Mild to moderate intensity exercise (150 beats per minute) increases fat and glucose oxidation by 5-10%.

The relative contribution of fat and carbohydrate utilisation to total substrate metabolism is dependent on exercise intensity, exercise duration, dietary and training status.

The contribution of fat oxidation during high intensity aerobic exercise (160 beats per minute) is substantially declined compared to low to moderate intensity exercise.

This is when carbohydrates are burnt and this crossover usually occurs as a result of abundance of glycolytic (carbohydrate breaking) enzyme instead of lipolytic (fat burning) enzyme.

Aerobic exercise and Fat burning zone

This cross over point (I just mentioned in earlier para) then gives rise to the idea of fat burning zone. It is commonly thought that low intensity workout will help burn more fat but what one tends to forget the total calories burnt.

For example walking may help burn 200 calories of which 60% is fat; that would be 120 calories of fat per hour. Jogging will help burn 500 calories of which 40% is fat which would be 240 calories of fat per hour and that is about twice the amount.

Whatever be the case both intensity of exercise translate to weight loss but only the time for results may differ. One way you can revamp your aerobic training is by trying out interval training that is doing different aerobic exercises with short bursts of high intensity.

What does research have to say about role of aerobic exercise in weight loss?

There is plenty of research on aerobic exercise and its effect on weight loss. And it is generally recommended as it thought to the best exercise for fat loss.

Multiple benefits linked with aerobic exercise

In comparison to a sedentary lifestyle any form of exercise equates to fitness and well being. Aerobic exercise is very popular for fat loss. In addition there is a number of health benefits linked to it.

Long term aerobic training improves exercise performance and aerobic fitness in individuals.  Both low and high intensity aerobic exercise benefits lipid levels and helps maintain lean mass.

Aerobic exercise should be recommended to those suffering from fatty liver disease.   Aerobic exercise along with diet induced weight loss improves glucose metabolism and insulin sensitivity.

aerobic image 2

Aerobic training also reduces obesity induced inflammation.   Regular aerobic exercise reduces the risk of developing cardiac diseases and improves lipid and cholesterol levels.

Adding aerobic exercise to a diet alone weight loss intervention causes significant loss of abdominal fat.  Among different aerobic exercises, it has been proven that walking and cycling are effective measures to lose weight.

Moderate intensity intermittent aerobic exercise for more than 150 min/ week is more efficient than continuous aerobic exercise in weight loss of obese and overweight women.  30 vs. 60 minutes of aerobic exercise produce similar weight loss results.

Metabolic rate reduces with loss of weight. If you don’t believe this read: Metabolism and weight. Aerobic exercise prevents decrease in metabolism occurring as a result of weight loss.

What does this mean?
Apart from causing weight loss, aerobic training helps lower cholesterol, improves insulin sensitivity, reduces liver fat and reduces risk of cardiovascular disease.

Moderate intensity aerobic exercise at 150 min per week is better than continuous aerobic exercise. Walking and cycling are scientifically proven to help in fat loss.

Aerobic training gets rid of harmful visceral fat

A review study  suggests that there is a dose dependant relationship between aerobic exercise and visceral fat reduction: more exercise greater fat loss.

Aerobic exercise, such as brisk walking, light jogging or stationary ergometer usage helps in reducing visceral fat. A 6 month study  showed that aerobic exercise combined with diet induced weight loss prevents and reduces fat deposition in the body especially in the trunk region.

A clinical trial  demonstrated that 8 weeks of aerobic exercise of different intensity and volume reduced liver fat and visceral fat to a small extent without affecting body weight.

Lee et al have shown that aerobic exercise and not resistance exercise is effective in reducing liver and visceral fat in adolescent girls irrespective of calorie restriction.

What does this mean?
Aerobic exercise is effective in reducing harmful visceral fat (fat wrapped around organs) and belly fat. This fat is harmful because it leads to development of metabolic and heart diseases.

Aerobic exercise affects appetite related hormones

Aerobic training alone is found to increase adiponectin levels.  Research shows that aerobic exercise 4 times a week for 12 weeks positively affects hormones like apelin and ghrelin which regulate fat deposition and metabolism.

It also lowers leptin in proportion to amount of exercise done.

Research suggests that aerobic exercise training promotes satiety while equivalent resistance training does not.

However other researchers have shown that despite of changes in appetite influencing hormones both aerobic and resistance training do not significantly affect energy intake.

What does this mean?
Research shows that aerobic exercise influences hormones that control fat deposition and appetite and this may have implications in obesity treatment.

Does aerobic exercise alone help in weight loss?

A combination of diet and exercise is the usual treatment for obesity. However scientists have also studied the effect of aerobic exercise alone.

aerobics image 3A review of 14 clinical trials demonstrated that aerobic programs lasting from 6-12 months led to a modest reduction in weight and waist circumference.  Researchers concluded that aerobic exercise alone is not effective for weight loss but when combined with diets it can be effective.

Donnelly JE and other researchers oppose this idea through their study.  Here the effect of aerobic exercise alone without calorie restriction on weight loss was studied. Individuals were assigned to exercise groups where the aim was to burn either 400 Calories or 600 Calories per session.

Weight loss for the 400 and 600 kcal/session groups was 3.9 kg (4.3%) and 5.2kg (5.7%), respectively. But the exercise period was quite long: 5 days a week for 10 months in the face of which the results don’t look significant.

Further research also shows that without dietary restriction you would need at least 9 months to observe full effect of aerobic exercise on weight loss.

Dengel et al state that addition of aerobic training to a hypocaloric diet does not help reduce loss of lean tissue.

What does this mean?
Aerobic exercise can lead to modest weight loss results which seem insignificant over the time span achieved. If combined with low calorie diet, its results are potentiated.

Aerobic vs. Resistance training: Which one is better?

Calorie restriction alone leads to weight loss as well as loss of muscle mass.  Therefore incorporating exercise in a weight loss program can prevent loss of muscle mass.

Aerobic exercise leads to loss of fat mass and improves overall health whereas resistance training prevents loss of and increases muscle mass and improves metabolic rate.

An important factor to be considered during a workout is the oxygen consumed and the metabolic rate raised. It is said that resistance training increases metabolic rate for hours post exercise which is why it is preferred over aerobic exercise.

Greer et al  studied the effect of steady state aerobic, intermittent aerobic and resistance training on metabolic rate. It was found that resistance and intermittent aerobic exercise raised metabolism for 21 hours in comparison to steady state exercise.

Ballor et al  compared the effect of resistance and aerobic training. The study lasted for 12 weeks. As per the results aerobic training group lost around 2.5kg while the weight training group lost only 0.4kg.

Additionally the weight training group gained weight but it is not mentioned whether lean or fat mass was gained.

A review study  comparing different exercise techniques and their effect on weight loss reported that a combination of aerobic and resistance training works the best.

As per the results aerobic training produces significant reduction in weight and waist circumference while resistance training is better for gains in lean mass.

A study  in older population showed that combination of aerobic and resistance training leads to increased gain in muscle mass and reduced percentage of body fat especially in arms and trunk region. The duo has also been proven to get rid of subcutaneous or superficial abdominal fat.

What does this mean?
Aerobic exercise causes fat loss while resistance training leads to muscle gain. It depends on your requirements and ability as to which one would be better for you. The combination of the two works best in reducing fat especially in trunk region.

What types of exercises are included in aerobic training?

A lot of exercises that you can do on your own come under aerobic exercise:

  • Walking
  • Running
  • Cycling
  • Swimming
  • Skipping
  • Boxing
  • Dancing

If you plan to hit the gym then these would come under aerobic exercise:

  • Stationary cycling
  • Indoor rower
  • Treadmill
  • Stairmaster

In case you are interested in knowing how much calories you burn with every exercise, then check out this link by Harvard Med School.

WHO suggests that ‘Adults aged 18–64 should do at least 150 minutes of moderate-intensity aerobic physical activity throughout the week or do at least 75 minutes of vigorous-intensity aerobic physical activity throughout the week or an equivalent combination of moderate- and vigorous-intensity activity.’

Precautions

There are no such significant measures to be taken to ensure safety during aerobic exercise. One precaution would be don’t eat 60-90 minutes prior to exercise and eating would mean a full fledged meal.

Keep yourself hydrated. Don’t overdo it and gradually increase the intensity of exercise. Consult a doctor prior to training to ensure that you are fit enough to engage in such activities.

Conclusion

Aerobic exercise seems like a safe and great way to start including some form of physical activity in your daily routine. In addition to helping with weight loss it also helps improve stamina and overall health of the individual.

Also it includes some easy exercise like walking and jogging which doesn’t need supervision. 30 minutes of exercise 5 days a week is enough to get you going.

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