Obesity is one of the most important public health problems of the present time , due to the high economic, social, personal and health costs derived from it, as well as its important impact on the quality of life in the short and long term. It is a multifactorial disease , a consequence of complex interactions between genetic, socioeconomic, sociodemographic, behavioral, and cultural influences, resulting from the imbalance between caloric intake and energy expenditure .
In addition, obesity constitutes a fundamental risk factor in the development of multiple pathologies : type 2 diabetes mellitus, cardio-cerebrovascular disease, dyslipidemia, arterial hypertension, obstructive sleep apnea syndrome, infertility, hypogonadism, non-alcoholic fatty liver disease , osteoarthritis, gastroesophageal reflux disease, and some types of cancer .
Obesity alone is clearly associated with higher mortality . It is estimated that for every 5-unit increase in body mass index (BMI) above 25 kg / m 2, overall mortality increases by 29%; vascular, 41%; and that related to diabetes, up to 210%. In relation to the economy and health, approximately 8.4% of health budgets are destined to provide treatment for diseases related to being overweight.
epidemiology
The prevalence of obesity is increasing dramatically in recent decades; a recent analysis with data from two hundred countries estimated the increase in the number of people with obesity from 105 to 650 million in the last forty years . If this trend continues, by 2025 one fifth of the world’s population would be obese. It is estimated that obesity directly causes almost three million deaths worldwide today.
The prevalence of obesity in adults in our country is above 20% . If we add the overweight subjects (around 35%), the fat ones far exceed half the population. In the last twenty years the prevalence of obesity in Spain has doubled. In childhood and adolescence the figures are no more optimistic. According to the Aladino study carried out with boys and girls between the ages of six and nine, it is observed that 58.5% of schoolchildren have normal weight values while 0.9% suffer from thinness and 40.6% have excess of weight. Of the latter, 23.3% are overweight and 17.3% suffer from obesity.
Prevention
Different factors highly related to obesity have been listed: age, marital status, low wealth index, urban residence, unhealthy dietary habits and easy access to junk food, pregnancy, obesogenic environment (urbanization and industrialization), long downtime, few hours of sleep, frequent use of transport or stress. There are many studies published in the medical literature on the changes and effects aimed at preventing obesity focused on the main identified modifiable risk factors. The commonalities in most of them are based on dietary interventions, as well as the promotion of physical activity.
The diet
The treatment or prevention of obesity through dietary interventions requires reaching a state of negative balance by reducing energy consumption . The best-studied dietary patterns include a diet oriented towards the Mediterranean diet , which emphasizes the intake of vegetables (fruits and vegetables, nuts, legumes, seeds), whole grains (cereals, breads, rice or pasta) and low-fat dairy, and limit red meat and fats, particularly saturated ones. This diet has been praised for its effectiveness in promoting safe long-term weight loss and reducing metabolic and cardiovascular risk factors . Some studies with adults have shown that the consumption of higher quality carbohydrates (higher fiber content and lower glycemic index), such as whole grains, nuts, fruits, vegetables and yogurt, are associated with lower weight gain.
A key factor in the quality of dietary patterns and the prevention of obesity are added sugars , sweeteners added to processed and prepared foods. In particular, a greater accumulation of visceral and liver fat has been reported, regardless of body weight in relation to sugar consumption. Several health agencies have recommended reducing the intake of added sugars to below 10% of the total caloric intake . In this context, the consumption of sugary drinks, eating out and taking out meals seem to be linked to an overall poor food quality. They are associated with higher energy intake, consumption of larger servings, long-term weight gain, and increased risk of obesity. Nutrition awareness, by providing correct nutritional information, as well as offering healthier food options in cafeterias and vending machines, appears to positively affect intake.
But the strategies that have been shown to be most effective are usually those that are directed at different foci. An example is the measure that was carried out in Oklahoma (USA), one of the places in the world with the highest obesity rates. The following institutional intervention actions were carried out there, among others: creation of parks, sidewalks, bike lanes and scenic walks through the city; equip each school with a gymnasium; allocate $ 100 million to create the best rowing and kayaking complex in the world; and burn with taxes on sugars. In addition, society was involved in the program also based on various social support actions: churches organized running clubs, schools analyzed menus, companies held competitions to lose weight, chefs in restaurants competed to offer dishes healthy and fast food restaurants promoted low-calorie menus. All these actions were highly effective, with a global weight loss of more than 450,000 kilos.
Physical activity
Sedentary behavior refers specifically to the time spent sitting, reclining, or lying down during waking hours. Physical activity is better for preventing weight gain than for promoting marked levels of weight loss in the more severely obese. However, physical activity is essential to prevent progressive weight gain in overweight or obese subjects. The American College of Sports Medicine recommends 150 to 250 minutes weekly of moderate intensity cardiorespiratory exercise and resistance training for each major muscle group two to three days a week to prevent weight gain.
Climbing stairs is a viable method of increasing physical activity in the public and work environment. Much attention has been paid to this strategy because of its ability to impact people who have the potential to use stairs in their daily routine or in their workplace; Encouraging participation in this habit can increase physical activity in a very broad demographic. Different studies have analyzed the potential benefit of implementing this measure, with significant decreases in body mass index, fat mass, waist circumference, diastolic blood pressure, and LDL cholesterol. Other studies have explored actions to avoid means of transportation by providing information on local routes for walking and using bicycles on the move.
Diagnosis
Obesity is defined as a state of excess fat tissue mass. As fat mass determination techniques are not widely available, the most widely used parameter worldwide is a formula that relates weight to height. The body mass index is the most universally accepted. Its formula is: BMI = weight / height . This index, when taking into account only the weight and not the weight of the fat, can produce the paradox that a bodybuilder has a BMI that classifies him as obese or overweight despite the fact that, in his case, the weight gain is of muscle tissue and not of fat mass. That is why the value of the BMI must be relativized.
Not all adipose tissue deposits are associated with the same magnitude of chronic disease risk. It is known that the increase in visceral fat is more associated with the risk of illness than the increase in subcutaneous fat . This observation has led to a search for body composition parameters with predictive value beyond BMI. Waist circumference is a measurement that measures both the subcutaneous and visceral adipose tissue. Although highly correlated with BMI, the measurement of waist circumference in some studies outperforms BMI in predictive value of disease risk.
Treatment
Medical treatment is based on lifestyle changes, drug treatment, and surgical treatment .
Changes in lifestyle
1. Reduction of caloric intake
Most of the strategies propose a reduction of 500-1000 kcal / day with respect to caloric needs. These are easily calculated using the basal metabolic rate (MB) according to the Harris-Benedit formula:
For men: basal metabolism (Kcal) = 66.5 + (13.75 x weight in kg) + (5.003 x height in cm) – (6.775 x age in years).
For women: basal metabolism (Kcal) = 655.1 + (9,563 x weight in kg) + (1,850 x height in cm) – (4,676 x age in years).
Subsequently, the expense is added depending on the degree of activity:
- Sedentary. Office work, truck driver, driver: RQD = MB x 1.2.
- Moderate activity. Clerk, police officer on foot: RQD = MB x 1,375.
- Intense activity Construction worker, lumberjack. RQD = MB x 1.55.
There are more sophisticated and accurate strategies for calculating basal metabolism than the Harris-Benedit formula, but they are available only to centers more specialized in the treatment of obesity. Among them, calorimetry , which determines a person’s energy expenditure at rest. By consuming energy, an exchange of gases occurs. To use up the calories provided by the nutrients, the body consumes oxygen and when it burns them, it produces carbon dioxide. Calorimetry approaches basal metabolism by measuring oxygen consumption and CO 2 production.
At this time there are many strategies that have scientific evidence to reduce caloric intake and that report weight loss including:
- Low-calorie diets based on the Mediterranean diet with a balanced distribution of immediate principles (fats, carbohydrates and proteins)
- Low-fat hypocaloric diets.
- Low-carbohydrate hypocaloric diets.
- Ketogenic diets that are very low in carbohydrates and that when metabolizing fat increase ketone bodies that decrease appetite, among other actions.
- Intermittent fasting is a strategy that has become fashionable in recent years and that is beginning to have scientific evidence that it is useful for losing weight. There are different modalities, such as skipping dinner or breakfast, eating a normal day and fasting another day or fasting three days a week compared to four with normal intakes. There are no large clinical studies to date that clarify which of the different strategies proposed is most effective in the long term to lose weight and maintain the weight lost.
2. Increased physical activity
Although this ploy, as we have said, have been shown to be effective in preventing obesity, for treatment, if not accompanied by a caloric restriction, weight loss will be more modest. The American College of Sports Medicine recommends a physical activity requirement of 225-420 minutes / week in case of overweight or obesity to promote weight loss; while to prevent weight gain after a successful loss, it would be 200-300 minutes / week.
3. Pharmacological treatments
In the last century we have lived with frustration the absence of effective alternatives for the treatment of obesity. Some of the drugs we used were withdrawn from the market because of long-term side effects. In recent years, the perspective on drug therapy for obesity has radically changed. At the present time in Spain three treatments are approved for the treatment of obesity.
- Liraglutide 3.0 mg (Saxenda). It is an analog of GLP-1, a molecule that is used for diabetes and reduces weight mainly because it slows the emptying of the stomach and reduces appetite. Clinical trials have been carried out with more than 3,500 participants where it has been observed that the weight loss after 56 weeks was 8% in the liraglutide 3.0 group compared to 2.6% with placebo (difference of 5.4 percentage points) .
- Bupropion and naltrexone (Mysimba). The combination of these two drugs causes a reduction in appetite. The combined administration of bupropion SR (360 mg) and naltrexone SR (32 mg), achieves average weight loss of 5% to 6.4% compared to 1.2% -1.8% with placebo (difference of 3.8-4.6 percentage points).
- Orlistat 120 mg (Xenical). This drug inhibits pancreatic lipase and therefore prevents a percentage of the fat we eat from being absorbed through the intestine. Treatment with Orlistat 120 mg three times a day results in a 4% weight loss relative to placebo.
At this time there are other very promising molecules in clinical development , such as Semaglutide 2.4 mg (GLP-1 analog) and Tirzepatide (GLP-1 analog plus GIP), which achieve reductions of greater than 10%. An unfortunate fact is that, in most countries with public health, these treatments are not funded by that institution.
4. Surgical treatment
Most scientific societies recommend performing bariatric surgery in people with BMI ≥ 40 kg / m2 or ≥ 35 kg / m2 with obesity-associated comorbidities, susceptible to improvement after weight loss. In recent years, they have also recommended an individual assessment of surgery in patients with a BMI between 30 and 35 who have major complications associated with obesity.
The most widely used surgical techniques at this time are the gastric sleeve – a surgeon removes part of the stomach and builds a narrow tube or sleeve with the rest – and the gastric bypass . This consists of reducing the size of the stomach until it has a capacity of 20-50 cc. Then it is connected directly to a more advanced section of the small intestine (bypass), so that only 60% of the mentioned route of the digestive system is used for the absorption of food.
Investigations and future forecasts
Currently there are numerous avenues of research open that can help us understand this pandemic and can provide new tools to prevent and treat obesity.
Genetics. The development of molecular biology at the end of the last century and the feasibility of carrying out genetic analyzes opened great expectations to unravel the genesis of obesity. Studies with twins and adoptive families show that the heritability rate of BMI is high, ranging from 40% to 70%. However, expectations have not been met in genome-wide studies; genetic variants have explained less than 5% of individual variation in BMI. Epigenetics may be a new discipline that sheds light on the lack of explanation for obesity by analyzing the complete genome of obese people.
New environmental factors. Among these we must mention inadequate sleep. Poor sleep or poor sleep has been shown to be a causative agent of obesity. Ghrelin increases and leptin decreases, and with it, appetite; alters thermoregulation; and causes asthenia during the day, which is associated with less physical activity. This relationship between poor sleep hours and obesity is clear in children and adolescents.
Another environmental factor is the changes in non-pathogenic microorganisms that are in our intestines, the microbiota , whose composition and biodiversity have changed dramatically in recent decades. In recent years, scientific evidence supports the idea that obesity and its metabolic consequences are closely related to changes in both the function and composition of the gut microbiota, which plays an essential role in modulating energy metabolism. The use of probiotics (live germs) or prebiotics (foods that modify the microbiota) to treat obesity is being tested, to date with few results.
Finally, thermal comfort , that is, less exposure to cold, has caused our brown adipose tissue to almost disappear, which, unlike white (the usual one), contributes to expending energy . Therapeutic targets are being studied in order to increase the activity of this tissue.
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Francisco Tinahones Madueño, Head of the Endocrinology and Nutrition Service of the Virgen de la Victoria Hospital. Professor of Medicine at the University of Malaga.
