Obesity and Exercise
The modern lifestyle favors obesity, which in recent decades has reached epidemic proportions, especially in developed countries.
Greece occupies one of the first places in Europe in obesity, concerning children and adolescents, as well as adults.
Obesity is a major current medical, social and economic problem. In addition, obesity is associated with several diseases that increase morbidity and mortality.
Obesity is classified according to Body Mass Index (ΒΜΙ).
Normal BMI: 18,5 - 24,9kg/m2.
People with BMI≥30kg/m2 are considered obese and
people with BMI≥40 kg/m2 are suffering from morbid obesity.
Risks of Obesity
Obesity is a strong risk factor for cardiovascular diseases, especially coronary heart disease, hypertension and vascular strokes.
Obesity is accompanied by vascular endothelial dysfunction and increased activity of the sympathetic nervous system in the heart, which contributes to the occurrence of arrhythmias and increases dramatically the risk of sudden death.
Respiratory problems are also serious, such as obstructive sleep apnea and daytime hypoventilation, which are responsible for pulmonary hypertension and right heart failure, polycythemia and drowsiness.
A common finding in obese people is the increased insulin secretion and insulin resistance, mainly due to lack of tissue sensitivity to insulin. Decreased tissue sensitivity to insulin causes metabolic syndrome and diabetes.
Obesity is also characterized by higher levels of cholesterol, triglycerides, LDL and high availability of free fatty acids. Thus, obese people have an increased risk of developing atherosclerosis, gallstones and thromboembolic events.
Obese people may also develop osteoarthritis, hernias, and cancers, such as: cancer of colon, pancreas, breast and endometrium. In fact, it seems that the risk is higher when people are obese during adolescence.
Mental health and social life
Finally, obesity has serious psychosocial consequences, as it negatively affects the self-esteem of the individual, increases stress and depression and leads to restriction of leisure and work activities of the individual and social isolation. Recognizing the problem, motivation and realistic goals are key principles of treating obesity. Obesity and Physical Activity Lack of physical activity is an aggravating factor. On the contrary, the combination of diet and exercise seems to bring the best results both in reducing weight and preventing and treating the complications of obesity. In addition to organized exercise, it is recommended to change the lifestyle, avoid a sedentary lifestyle and increase individuals’ daily activity, in order to increase calorie intake with simple and regular physical activities. Diet exclusively leads to muscle atrophy, especially in the elderly patients. In fact, after diet is interrupted, body fat increases, in contrast to muscle mass, so the problem intensifies. Exercise leads to fat oxidation and thus reduces body weight, while causing an increase in skeletal muscle.
Exercise in obese patients
Exercise programs should be well-designed to be beneficial and safe. Obese people should exercise after a thorough medical examination, in order to significantly reduce the complications that may occur by the following program.
Exercise programs for obese people should be based on:
- body weight,
- functional capacity and
- their personal obligations.
Despite the initial grouping, the program must have individual characteristics and goals. Exercise should be focused on entertainment, new interests’ creation and it should be enjoyable.
Obese people should also be encouraged and supported psychologically at the beginning of the program, since a large percentage of obese people are frustrated by several reasons (non-spectacular weight loss, easy fatigue, lack of confidence, inability to perform certain exercises, etc.) and give up the effort.
Maintaining and/or losing weight requires an active lifestyle with daily increased physical activity.
An effective exercise session should be designed to consume about 200-300 kcal and have a specific intensity, frequency and duration.
Organized exercise programs with beneficial results should be done at least 3-5 times/week.
The most common exercise programs are those that include aerobic activities such as walking, cycling, dancing and swimming. Exercising in water has also very good results. The stationary bike is also ideal, at least in the early stages, because it supports the weight and the obese person maintains its balance better. Particular attention should be paid to warm-up and cool-down, which should necessarily accompany the main part of the exercise.
The program should also include stretching exercises, since they contribute to mobility increase and muscle injuries’ reduction.
When an obese person enters into an exercise program, low-intensity exercise and relatively long duration are suggested, in order to achieve the necessary fat loss.
Exercise and energy
In low-intensity exercise [about 25-40% of the maximum oxygen uptake (VO2max)], plasma free fatty acids (FFA) are used as energy fuel.
In high-intensity exercise the main source of energy is glycogen rather than fat.
From moderate to high intensity exercise (~65% VO2max) free fatty acids and extra glycogen and possibly part of the intramuscular fat are used as energy sources.
Therefore, initially exercises’ intensity is recommended to be in the range of 40-60% of the maximum capacity for work of the individual, depending of course on his state of health. The total burden of each exercise session at the beginning of the program should not be large, to prevent complications and injuries and to avoid the person’s disappointment from the early feeling of fatigue.
Gradually, the intensity and duration of exercise should increase according to the adjustments and the performance of patient. Thus, the goal is for the intensity to gradually correspond to about 50-85% VO2max or to 60-90% of the maximum predicted heart rate or at the expense of 7.5-10 kcal/min and the duration to reach one hour totally.
In recent years, more health centers implement strengthening programs for obese people, as exercise contributes not only to maintain and increase muscle mass, but also to improve body composition.
Muscle strengthening exercises should be characterized by low intensity and many repetitions. The total duration of the program has a key role. Significant benefits come after about 4-6 months of exercise and of course the goal is lifelong exercise.
Of course, the results are greater and more permanent when exercise is combined with the appropriate hypocaloric diet. Unfortunately, the sooner exercise interrupts, the sooner it leads to loss of all its beneficial effects.
Benefits of exercise in obese patients
The weight loss caused by regular physical activity is a result of increased energy consumption, decreased appetite, reduced total body fat and transient fluid loss through sweating. However, it seems that these favorable results mainly concern the overweight and the moderately obese and to a very small extent the excessively obese.
Many studies suggest that weight loss with regular exercise ranges from 3 to 15 kg depending on the duration and nature of the intervention.
This reduction is of course greater when exercise is accompanied by appropriate dietary programs. The combination of exercise and hypocaloric diet is the best way to treat obesity.
Excessive diet may lead to a reduction in both body fat and useful “dry” muscle mass, while exercise increases muscle mass.
In addition, a strict diet could lead to psychological disorders, while physical activity undoubtedly psychologically supports the individual. There are also several observations referring to the appetite decrease with exercise in obese patients.
Effect on metabolism
Exercise affects glucose metabolism. Systematic exercise improves glucose tolerance. In obese individuals, both insulin levels and plasma circulating insulin levels are reduced and tissue sensitivity to lipid insulin is increased.
Effect on the cardiovascular system In general, the immediate mechanisms by which regular exercise offers cardiovascular benefits are:
- reduction of myocardial oxygen demand (decrease in resting heart rate),
- reduction of systolic pressure (reduction of the level of catecholamines circulating in the plasma),
- increase of blood supply to the myocardium (increase of coronary artery blood flow, creation of collateral circulation, etc.),
- and increase of pulse volume, decrease of peripheral vascular resistances, etc.
- Exercise may also help treatment of hypertension, especially in obese women, even when it does not lead to significant weight loss. Effect on the musculoskeletal system Systematic exercise helps to maintain the flexibility of the joints and slow down their degenerative lesions, as well as of the spine, which is particularly strained in obese people.
It also inhibits or slows down the onset of osteoporosis. At the same time, it acts favorably on the metabolic processes of the skeletal muscles, increasing the number of mitochondria and their oxidative capacity.
Exercise improves the respiratory function of obese people, as it increases functional residual pulmonary capacity and the ventilation-perspiration relationship becomes normal.
Finally, the contribution of exercise is important in removing the feeling of fatigue of the obese person, in increasing his self-confidence, in improving his social behavior and therefore in his psychological support and mental balance.
The increase in the functional capacity of the individual is accompanied by:
- self-service capacity improvement,
- increase of self-confidence and self-esteem,
- improvement of the feeling of well-being,
- stress and depression levels decrease and,
- social and professional reactivation increase.
Finally, evidence shows that exercise reduces cardiovascular mortality by 20-25%.