Dissatisfaction with the body and the medical problems associated with being overweight are two of the most frequent concerns in a society plagued by the epidemic of obesity and eating disorders.
New and reversed “miracle diets” appear constantly, showing that we are facing an unresolved issue on which there continues to be a demand from society. The strategies for weight loss focus on weight loss diets (low in calories) and exercise.
But when it comes to losing kilos it is important to know at the expense of what we lose, fat or muscle? How does the woman’s body respond to changes in diet and physical activity? We all know the seemingly simple equation of energy balance that we are faced with when we want to lose weight: the energy that enters in the form of food and that is spent throughout the day. But the variables of this balance interact and when we manipulate one of them the body sets in motion mechanisms to compensate it, with which the balance balances again and losing weight becomes difficult. But before continuing, I invite you to watch this video if your goal is to lose weight.
What do we spend energy on?
Our total energy expenditure in one day includes:
- Basal expenditure is what the body consumes while resting to maintain vital functions and accounts for most of the energy consumed
- Spending to digest and absorb food (yes, eating consumes energy)
- And finally, the expense for physical activity, which is the most variable
In view of these three ways to spend calories, the ideal would be to increase those we consume at rest.
Well, and on what does the spending at rest depend? Mainly from muscle mass (lean body mass), although age, sex, genetics, temperature, nutritional status, thyroid status also influence …
People with greater muscle mass, younger, and better nourished have higher energy consumption at rest.
With age, basal expenditure decreases, an increase in fat mass, and loss of muscle occurs, changes that are related to the trend of a more sedentary life over the years. There are studies that have demonstrated a higher expenditure in rest in women between 35 and 50 years of age who exercise regularly (9 hours a week), compared to those considered sedentary.
As muscle mass is the determining factor of resting expenditure, weight loss, and weight loss programs must avoid muscle loss and achieve weight loss through a reduction in body fat.
Increasing muscle mass
Can we increase our muscle mass? Yes, the exercise that increases muscle mass more effectively is anaerobic, the one in which we perform muscle contractions with resistance exercises and weight exercises.
The calorie expenditure of strength training in itself is lower than that of aerobic exercise (running, swimming, cycling …) and therefore by itself does not lead to weight loss, but develops changes in female body composition (increased muscle mass and decrease in fat mass) that can increase spending at rest and thus help in weight control.
What is the exercise that consumes the most energy?
Aerobic, the one we do when running, cycling, swimming, light walking … With the practice of this type of exercise, we can consume calories during training. It has been objectified that, although not in all types of practices or people, an increase in calorie expenditure may persist in the hours after exercise and continuously during rest.
The amount of energy we spend with the exercise will be determined by its intensity and duration. We know that during high-intensity aerobic exercise there is a higher calorie expenditure than with low-intensity exercise, however, maintaining an intense exercise over time is exhausting so an efficient training plan would be one that includes exercise intervals high intensity with others of lower intensity.
If you prefer or we can only practice low-intensity exercise it will be necessary to do it more frequently and for a longer time to achieve a notable weight loss. In any case, weight loss through aerobic exercise, without caloric restriction, is possible but requires high intensity and frequency of training on the part of the woman.
It has been seen that the effects of physical exercise are highly variable in each person depending on the state of previous training, the type of exercise that is practiced, the intensity and frequency, if compensation is made (voluntary or involuntary) of the expense with the intake …
Despite not being the central tool in weight loss, it must be borne in mind that physical activity plays a very important role in maintaining weight once it has been lost and is essential support during the weight loss phase.
What is the effect of combining both types of exercise?
The combination of aerobic and anaerobic exercise represents an improvement in health, although it has not been fully demonstrated that practicing both together leads to greater weight loss than aerobic exercise in isolation.
In recent years, research is being carried out with exercise protocols of approximately 20 minutes duration, alternating short high-intensity cycles (8-15 seconds) with low-intensity cycles (15-20 seconds), achieving considerable reductions in fat mass in young women. ; Although the optimal duration of the different exercise cycles remains to be established, it seems to be a solution to the lack of time dedicated to sports.
How do diets affect energy balance? What happens when we diet?
The hypocaloric diets achieve a reduction in weight but when ingested very low calorie the body diminishes it spends idle through different mechanisms (leptin levels of thyroid hormone activity sympathetic nervous system …), to compensate for the balance.
Another event that occurs with diet weight loss alone is an undesirable loss of muscle mass associated with desirable fat reduction.
It has been seen that combining diet with aerobic exercise we can achieve significant weight loss to a greater extent than with diet alone. This combination attenuates the loss of muscle mass.
On the other hand, there are studies that have shown that overweight young women who start a very restrictive diet (less than 1000 kcal/day) have a lower energy expenditure after practicing moderate-intensity exercise compared to those who exercise following an intake. adequate caloric, therefore, seems reasonable, does not make very-low-calorie diets because the body defends itself by decreasing its resting energy expenditure, which makes it very difficult to lose weight.
The effect of diet on body composition varies depending on the content of macronutrients (proteins, carbohydrates, and fats) in the diet. Currently, research is underway on what may be the most beneficial proportion to avoid loss of muscle mass without damaging other organs. This change in proportions should not be based on drastically limiting the intake of any of the macronutrients, because diets, whether hyper protein or very low in fat, can have non-beneficial consequences for health.
As already noted, hormonal status influences energy expenditure. The thyroid is one of the endocrine glands involved and one of the most frequent endocrine diseases in women, hypothyroidism, sits on it.
Thyroid function adapts variably to exercise with both increasing and decreasing levels of thyroid hormones in relation to the type and duration of exercise, ambient temperature, and caloric intake. One of the most constant changes that have been observed when exercising associated with a deficit in intake is that there is a greater transformation of the thyroid hormone T3 inactive to inactive form (rT3) in order to decrease energy expenditure. It is the body’s way of adapting to the “stress” of energy reduction.
How can thyroid failure affect weight loss and exercise?
The primary hypothyroidism is a situation in which the thyroid is unable to produce thyroid hormone (T4 and T3) in amounts necessary, and without treatment results in decreased energy expenditure. We currently have tablets that contain thyroid hormone type T4, which is less active than T3. The transformation of T4 into T3 is carried out in different organs.
In women who suffer from hypothyroidism, it is the thyroid gland that fails and thanks to the treatment we can reestablish the optimal levels of the hormone. Once the treatment has been adjusted correctly, the rest of the organs are in charge of making the hormonal conversion (go from T4 to T3) depending on their metabolic needs.
The functioning of the body of the hypothyroid woman who follows a correct treatment is totally normal, having no limitations, for this reason, for weight loss or for the practice of exercise.
- The weight should be understood as a marker of our health, not as the object of fighting ourselves.
- The physical activity is the only component of energy expenditure that is under our control and we can change voluntarily.
- The exercise is a stimulus to boost loss and the best tool for maintaining a stable weight.
- The strength training without dietary changes generally but has shown changes in body composition (increased muscle mass and decreased fat mass) is not translated into a weight loss
- The greatest benefit is achieved by associating aerobic and anaerobic exercise.
- The weight loss achieved with a low-calorie diet includes fat and muscle mass, to reduce the loss of the latter it is advisable to include exercise.
- A very low-calorie diet can have a negative effect on energy balance and pose a health risk.
- Regardless of the weight loss achieved with exercise, it has numerous benefits for women’s health (preventing osteoporosis, improving mood, avoiding weight gain, promoting plasticity and brain function, reducing cancer risk …)
- The sedentary lifestyle is a risk factor of diseases of all types (cardiovascular, cancer, metabolic as diabetes, osteoporosis …).