Is aerobic exercise the best choice for those who want to lose weight?

Aerobic exercise, in the imagination of many people and health professionals, is now considered the best strategy to promote slimming. The theory behind this consideration is that, during aerobic exercise, the caloric expenditure of the activity is greater than that of training against resistance. This would mean that, if prolonged over the months, aerobic exercise would have a greater impact on the energy balance, making it negative and leading to the much desired reduction in fat mass.

On the other hand, there is a growing consensus that long-term progressive resistance exercise is a more effective option for those who want to lose weight. Some concepts in favor of this idea are:

• Endurance training increases lean mass, increasing daily energy expenditure
• resistance training, because of the higher intensity used, would increase the insulin sensitivity of muscle tissue

• Endurance training promotes the distribution of nutrients in favor of muscle tissue over adipose tissue.Considering this, is aerobic exercise the best choice for those who want to lose weight? To give a response that is supported by data, rather than by beliefs, you must bring attention to the scientific studies carried out on the subject.

The scientific literature of reference, however, does not give a clear answer about aerobic exercise. Before continuing, it is important to stress the centrality of the negative energy balance in weight loss/fat mass and how aerobic exercise must then be integrated with a diet that is low-calorie (in the case of those who want to lose weight).

For fat mass loss, the guidelines have historically recommended prolonged low-intensity aerobic exercise. However, in recent years, exercise against resistance has gained increasing popularity in science, as it regards the ability to induce fat mass loss. A study that questioned this body of knowledge and guidelines was published in 2012. The authors point out that the guidelines on exercise against resistance and weight loss were not concretely reflected in the various studies published on aerobic exercise. The study by Willis and colleagues was, therefore, the first to compare three groups of people randomly assigned to a group that performed aerobic exercise (AE), against resistance (CR) or a combination of the two (M).

Comparative studies about aerobic exercise

After a period of 8 months the results were as follows:

• body mass decreased significantly in groups Aerobic Exercise and Mixed, while it increased in group CR;
• fat mass and waist circumference decreased significantly in groups Aerobic Exercise and M, remaining unchanged in group CR; finally, lean mass increased in group CR but not in groups AE or M.

The main results of the study were as follows:

• resistance training alone does not reduce body mass or fat mass;
• aerobic exercise reduces body and fat mass more than resistance training;
• the combination of the two training modes does not reduce body and fat mass more than aerobic exercise alone.

However, this is only a study: it is not clear in the literature whether resistance training can be a better alternative to aerobic exercise in reducing fat mass, with some research confirming this hypothesis, while others deny it. Despite the lack of scientific evidence, resistance training is considered effective in reducing fat mass.

This consideration is given by the fact that several articles about aerobic exercise report tables showing how resistance training reduces the percentage of fat mass, suggesting that this means a reduction in the absolute value of fat mass. Instead, as reported in the study by Willis and collaborators, resistance training led to a decrease in the percentage of fat mass without any change in the absolute value of fat mass.

This is because resistance training leads to an increase in lean mass. Aerobic exercise has resulted in a greater reduction in both body weight and absolute fat mass than endurance training, although changes in the percentage of fat mass are similar. The changes take place through different mechanisms: resistance training increases lean mass, while aerobic exercise reduces fat mass.

HIIT and the latest trend to lose weight

Although Willis's study puts an order in terms of diatribe aerobic exercise against endurance, another mode of training has become more and more established in recent years, to be the first trend in fitness in the year 2018: we speak of high-intensity interval training (HIIT).

Some articles suggest that this is more effective than aerobic exercise in reducing body fat, although its nature is anaerobic: most studies have focused on a model consisting of 30 seconds of maximum effort alternating with 4 minutes of active recovery.

If HIIT can be an efficient alternative to classic aerobic exercise, what are the mechanisms by which this happens? A brief review in 2016 suggests that high-intensity training would cause a redistribution of hydrocarbons in favor of muscle tissue compared to adipose tissue.

The exercise increases, in fact, the insulin sensitivity of the muscle that contracts that, to return to a condition of balance after an enough stimulus, will require more food hydrocarbons than the adipose tissue. This, according to Kuo's elaboration, would lead to a redistribution of hydrocarbons and a more favorable body composition. Muscle growth is more likely to be induced by high-intensity exercise than aerobic exercise since more cell regeneration is needed after more muscle damage, this would provide an explanation for the mechanism by which HIIT would provide a greater reduction in fat mass than low-intensity aerobic exercise.

The solution is to increase the intensity of training

What can the professional in the sector grasp from this information? Training programmes for an overweight or obese person who wants to lose weight and improve their physical appearance (a profile corresponding to most clients who hire a personal trainer) should guide the person to sustain a progressively higher training intensity, both in relative and absolute terms.

We start by giving greater importance to aerobic exercise, but without neglecting the training against resistance, the basis of which will be set (exercise technique). As the fat mass reduces and reaches normal values (15% for men - 25% for women) it is advisable to increase the time dedicated to training against resistance, to increase the muscle mass of the individual.

How much time to dedicate and how to implement each training mode will obviously depend on the person in front of the professional (initial fat mass, training experience, time available, etc..). In short, nothing new for professionals, but finding scientific data and literature to support their knowledge is now more important than ever.

Fitness medicalization

In fact, there is an increasing medicalization of fitness and there is an increasing need to skim the abundance of poor information that the Internet and the marketing of products/services make available to everyone.

The most common objection that can be made to the above is as follows: "f the necessary condition for losing weight and fat mass is a negative calorie balance, then it is better than the person combines a low-calorie diet with resistance training. In this way, they can gradually lose weight while maintaining their muscle mass and improve their appearance.

In the end, people say they want to lose weight, but what they want is an athletic, muscular and dry body, something that aerobic exercise cannot give. This option may make sense for individuals who have normal fat mass values (< 15% men - < 25% women) but it would not seem advisable for overweight or obese individuals for all the above reasons.

Furthermore, the approach suggested in the article clearly states that aerobic exercise can be very important at the beginning but agrees that it should leave room for progressively more intense work.

Aerobic exercise? Depends on the person

In conclusion, the answer to the question Is aerobic exercise the best choice for those who want to lose weight? is anything but a dry Yes or No. How the answer was examined is strongly influenced by the level of the person: the approach is different for those who want to go from 30% to 15% of fat mass, for those who want to go from 15% to have the abdominals clearly visible or for those who want to define themselves for a bodybuilding contest.

The personal trainer will evaluate each time which the optimal approach is based on the person in front of him. To give an answer that concerns a slice of the population very widespread, overweight people, aerobic exercise is the best choice for an initial period, after which it will have to leave room for more intense workouts and can be used in recovery sessions or in the weeks of discharge. This is a direction to go in, on a practical level the approaches are then theoretically as many as there are people who turn to the professional.

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