Are you happy with your body weight? If so, you are a rare person. Most people in our society think that they should be overweight or underweight (mostly underweight). In general, their primary concern appears to be, but they often find that physical health is also somehow related to body weight. One does not necessarily cause the other – that is, ideal body weight does not guarantee good health. Instead, both depend on food and physical activity. A balanced diet and an active lifestyle promotes good health. A balanced diet maintains a healthy body weight. In this article you will find the health risks and causes of overweight and obesity.
Weight gain occurs when energy intake exceeds the energy consumed. Conversely, weight loss occurs when the energy consumed exceeds the energy intake. In the most extreme cases, both being overweight and underweight have health risks. Weight management is an essential component of good health.
Overweight And Obesity
The prevalence of overweight and obesity is still high in the United States. Because of the change in methods, the prevalence of obesity before 2011 cannot be estimated between later years, but trends clearly show that in the last five decades, in every state, in both sexes, obesity has increased in all ages. An estimated 70% of adults in the United States are considered overweight or obese, as defined by a BMI of 25 to 29.9 or 30.
At the very least, the risk of being overweight among children in the United States has risen alarmingly. Obesity has spread worldwide, affecting 1.9 billion adults and children under the age of 41. Rising rates of obesity in countries around the world reflect the global food system that provides energy-efficient, affordable and efficiently marketed products. Before examining the suspected causes of obesity and the different strategies used to treat it, it is helpful to understand the development and metabolism of body fats.
1. Fat Cell Development
When the “input energy” exceeds the “output energy”, much of the excess energy is stored in the fat cells of the adipose tissue. The amount of fat in adipose tissue reflects both the number and size of fat cells. The number of fat cells increases most rapidly during the growing years of late childhood and early adulthood. After growth has stopped, the number of fat cells may continue to increase as the energy balance is positive. People who are obese have larger fat cells than people of a healthy weight.
Excess fat fills the body’s natural storage site first – adipose tissue if fat remains abundant, the excess is deposited in organs such as the heart and liver. The fats that accumulate outside the adipose tissue – called ectopic fats – disrupt normal metabolism and contribute to the development of diseases such as heart failure and fatty liver. As fat accumulates outside the womb, metabolic changes that indicate disease risks – such as insulin resistance – become apparent and chronic inflammation develops.
2. Fat Cell Metabolism
The enzyme lipoprotein lipase (LPL) plays a major role in the metabolism and transport of fats, and thus is involved in the development of obesity. One of its roles is to remove triglycerides from the blood to store them in adipose tissue and muscle cells. Obese people have higher LPL activity in fat cells than lean people. This high LPL activity makes fat storage particularly effective.
Thus, even modest excesses in energy intake have a more dramatic effect on obese people than lean people. LPL activity in different areas of the body is partly affected by sex. In women, fat cells in the breasts, hips and thighs produce an abundant amount of LPL, and fat is stored in those sites of the body; in men, abdominal fat cells produce an abundant amount of LPL. This enzyme activity explains why men tend to have central obesity around the abdomen while women are more likely to develop lower body fat around the hips and thighs (pear-shaped).
Gender differences also manifest themselves in the activity of lipase enzymes, which control the release and breakdown of fat in different parts of the body. Lower body fat release is less active in women than in men, while upper body fat release is similar. Moreover, the rate of fat breakdown in women is lower than in men. Thus, women may have more difficulty losing fat in general, and from the hips and thighs in particular.
3. Set Point Theory
Many physiological changes, such as blood glucose, blood pH, and body temperature, remain quite stable in a variety of variations. The hypothalamus and other regulatory centers constantly monitor conditions and carefully adjust them to maintain homeostasis. The stability of such complex systems may depend on point control regulators which maintain the variables within specified limits.
Researchers emphasized that after weight loss, the body modifies its metabolism in favor of restoring the weight. The decline in metabolism after weight loss is greater than would be expected based on body composition alone. This adaptation helps explain why maintaining weight loss is difficult.
Causes Of Overweight And Obesity
Why do people accumulate excess body fat? The obvious answer is that they consume more energy from foods and drinks than they do in physical activity and metabolic processes. But this answer does not explain why they do so. Is it hereditary? The environment? Cultural? Behaviorism? Social and Economic? Metabolism? All of these? Most likely the latter. Many factors contribute to the development of obesity and most of them are interrelated. Here we discuss the main factors contributing and interacting – genetics and the environment.
Genetics And Epigenetics
Genetics plays a clear causative role in relatively few cases of obesity, for example, in Prader-Willi syndrome – a genetic disorder characterized by excessive appetite, obesity, short stature and often intellectual disability. However, most cases of obesity are not caused by a single gene. More than 100 sites in the human genome are associated with obesity and lipid distribution.
Obesity is a classic example of epigenetic regulation. Researchers have been examining the human genome for genetic and epigenetic answers to obesity questions. Every cell expresses only the genes for the proteins it needs, and each protein performs a specific function. Few proteins help explain appetite control, energy regulation, and the development of obesity.
The obesity gene, called ob, is mainly expressed in adipose tissue and leptin codes for the protein. Leptin acts primarily as a hormone in the hypothalamus. Leptin maintains balance by regulating food intake and energy expenditure in response to adipose tissue. As body fat increases, so does the hormone leptin – which limits appetite. When body fat is low, the hormone leptin decreases – which stimulates the appetite and reduces energy expenditure. In short, leptin promotes a negative energy balance and reduces body weight and obesity.
Another protein, known as ghrelin, also functions as a hormone primarily in the hypothalamus. Unlike leptin, stomach cells mainly secrete the hormone ghrelin and it promotes positive energy balance, increased body weight and obesity. Ghrelin stimulates the appetite and raises the craving for food. Ghrelin levels in the blood usually rise before a meal and decrease afterwards – reflecting the hunger and satiety that precedes and follows eating.
On average, Ghrelin levels are high when the body is in a negative energy balance, as occurs during low-calorie diets, for example. Ghrelin levels drop when the body is in a positive energy balance, as they do with weight gain.
3. Uncouple Protein
Genes also encode proteins involved in energy metabolism. These proteins may affect the storage or expenditure of energy with different efficiencies or in different types of fats. The body has different types of adipose tissue and the amounts of each are determined by genes. White adipose tissue stores fat for other cells to be used for energy. Brown adipose tissue releases stored energy in the form of heat, thus protecting against cold and preventing obesity.
Environments That Promote Overweight And Obesity
When the rate of obesity increases and genes remain relatively unchanged, the environment must also play a role in obesity. Obesity represents the interaction between genes and the environment. The obesity environment encompasses all the conditions that we encounter on a daily basis that drive us towards obesity. Over the past several decades, the demand for physical activity has decreased with increasing food availability, challenging the human body’s ability to defend against weight gain.
Keep in mind that genetic and environmental factors are not mutually exclusive. In fact, their interaction produces epigenetic genes that provide a better understanding of obesity and related diseases. Genetics can affect eating habits, for example, eating and activity behaviors affect the genes that regulate weight in the body. Interestingly, even social relationships can affect food choices and the development of obesity. When a friend, sibling or spouse gets fat, a person is more likely to get fat.
One explanation for obesity is that overweight people gain more weight, although diet history does not always come in large quantities. Diet histories are not always accurate records of actual intake. Both normal weight and obese people usually misuse their diet.
Most importantly, the current diet does not reflect the eating habits that lead to obesity. Obese people who have had a positive energy balance for years and may accumulate more body fat may not have a positive energy balance at this time. Both current and past eating and activity patterns affect current body weight.
2. Physically Inactive
Our environment also promotes physical inactivity. Life requires a little hard work. Instability plays an important role in weight loss and poor health. Watching television, playing video games, and using a computer is mostly physical sophistication. The more time people spend in these blasphemous activities, the more likely they are to be overweight, the more likely they are to pick up the metabolic risk factors for chronic and chronic diseases (high blood lipids, high blood pressure, and high blood glucose). Restless activities can help you gain weight in many ways.
- First, they simply need less energy than their metabolic rate.
- Second, they replace the time spent in more active activities.
- Third, watching television affects food purchases and interacts with food snacking on high calorie, solid fats. The most heavily advertised sugary foods and beverages.
People can be obese, therefore, not because they eat too much, but because they move too little, not only in purpose-related exercise, but also in the activities of daily life. Studies have shown that the difference in time between obese and lean people consumes about 350 kcal a day in lying, sitting, standing and eating. In general, lean people are more active in their careers and leisure time. The energy expended in non-invasive everyday activities – called non-exercise activity thermogenesis (NEAT) – performs a significant function.
Problems of Overweight and Obesity
Millions of American adults are trying to lose weight any day. Some of them may not even need to lose weight. Others may benefit from weight loss, but they will not succeed. Very few people succeed in losing weight, and even fewer succeed permanently. For many people, further dieting and improving exercise habits may be enough to prevent weight gain. Whether a person will benefit from weight loss is a health question.
Obesity produces many health issues. Health professionals use BMI and waist circumference to determine the potential health risk of obesity. BMI is high and as the length of the waist increases, so does the risk of heart disease, type 2 diabetes, and any other cause of death. Weight loss is recommended for people with obesity (BMI ≥ 30) and for those who are overweight (BMI 25 to 29.9) with one or more obesity risk factors associated with:
- Fatty liver disease
- Abnormal blood lipids
- Diabetes or pre-diabetes
- Sleep apnea
Simple weight loss can improve blood lipids, blood glucose and blood pressure. Losing more weight can have more benefits and may even reduce the need for medication.
Also, read this article: Why Do We Get Fat? The Science Behind Being Overweight