Energy Balance (Obesity, Undernutrition, Malnutrition) PDF

Energy balance (obesity, undernutrition, and malnutrition) Prepared and presented by Dr. Sherif Diaaeldin Assistant Professor of Physiology Definition Energy balance is defined as the state achieved when the energy intake equals energy expenditure. This co...

Energy balance (obesity, undernutrition, and malnutrition) Prepared and presented by Dr. Sherif Diaaeldin Assistant Professor of Physiology Definition Energy balance is defined as the state achieved when the energy intake equals energy expenditure. This concept may be used to demonstrate how bodyweight will change over time in response to changes in energy intake and expenditure. When the body is in energy balance, bodyweight is stable  Energy intake: The amount of energy we take in from food and drinks is known as energy intake. This is influenced by the type and amount of food we eat, as well as the frequency with which we eat. Energy expenditure: The amount of energy we expend through physical activity and bodily functions is known as energy expenditure. This is influenced by the amount of exercise we do, as well as our metabolism. Our metabolism is the rate at which our bodies convert food into energy. It is influenced by several factors, including our age, sex, and genetics.  Humans take in energy through the intake of food and drink and expend energy through the resting metabolic rate (RMR)—the thermic effect (TEF) of food and physical activity. The RMR is the energy expenditure required for maintaining normal body functions and homeostasis. TEF refers to the energy required to absorb, digest, and metabolize the food consumed and typically accounts for 8–10 % of daily energy expenditure. Factors affecting the basal metabolic rate (BMR) include: Body Composition: Fat-free mass and fat mass influence BMR. Lean body mass, especially muscle mass, requires more energy to maintain, thus contributing to a higher BMR Age: Metabolism generally slows with age due to a loss of muscle tissue and changes in hormonal and neurological processes Body Size: Larger adult bodies with more metabolizing tissue have a larger BMR Gender: Men generally have faster metabolisms than women, partly due to their larger size Genetics: Genetic predisposition can partly determine metabolic rate  Physical Activity: Exercise increases muscle mass and can increase BMR, as hard-working muscles need more energy Hormonal Factors: Hormonal imbalances, such as hypo- and hyperthyroidism, can affect metabolism Environmental Factors: Changes in environmental temperature, such as increased heat or cold, can affect BMR as the body works harder to maintain its normal temperature Drugs: Certain substances like caffeine and nicotine can increase BMR, while some medications may affect metabolism What is the difference between BMR and RMR Basal metabolic rate (BMR) and resting metabolic rate (RMR) are similar but have slight differences. BMR is the minimum number of calories required for basic functions at rest, while RMR, also called resting energy expenditure (REE), is the number of calories that your body burns while it’s at rest. BMR is usually measured in a darkened room upon waking after eight hours of sleep, 12 hours of fasting to ensure that the digestive system is inactive, and with the subject resting in a reclined position On the other hand, RMR has fewer restrictions and can be measured under less restricted conditions than BMR. Obesity Obesity is a condition of excess body fat. It is defined as having a body mass index (BMI) of 30 or greater.  Causes of obesity: 1. Genetics: Some people are more genetically predisposed to obesity than others. 2. Diet: Eating too much calorie-dense food and drinks is a major cause of obesity. 3. Physical activity: Not getting enough exercise can contribute to obesity. 4. Several medical conditions can contribute to obesity. These include: Hypothyroidism: Thyroid hormone plays a role in regulating metabolism, and when levels are too low, metabolism slows down, leading to weight gain. Cushing syndrome: When cortisol levels are too high, it can lead to weight gain, particularly in the trunk and face. Polycystic ovary syndrome (PCOS): PCOS is a hormonal disorder that affects women of reproductive age. It is characterized by irregular menstrual periods, excess androgen production, and insulin resistance. Insulin resistance can lead to weight gain, particularly around the abdomen.  Prader-Willi syndrome: Prader-Willi syndrome is a genetic disorder that causes a chronic feeling of hunger and an inability to control appetite. This can lead to significant weight gain. Low levels of leptin: Leptin is a hormone produced by fat cells that signals to the brain that you are full. Low levels of leptin can lead to increased appetite and overeating. High levels of ghrelin: Ghrelin is a hormone produced by the stomach that signals to the brain that you are hungry. High levels of ghrelin can lead to increased appetite and overeating. Medications: Certain medications can also contribute to weight gain, including corticosteroids, some antidepressants, and antipsychotics. These medications can affect metabolism, appetite, or fluid balance, leading to weight gain.  Obesity increases risk for many other diseases which include: Heart disease: People with obesity are more likely to have high blood pressure, high cholesterol, and high triglycerides, which are all risk factors for heart disease, coronary artery disease, heart attack, and stroke. Type 2 diabetes: People with obesity are more likely to have insulin resistance, which is a precursor to type 2 diabetes. Certain cancers: Obesity is a risk factor for several types of cancer, including endometrial cancer, breast cancer, colon cancer, kidney cancer, and pancreatic cancer. Osteoarthritis: Obesity is a major risk factor for osteoarthritis, a degenerative joint disease that causes pain and stiffness. The excess weight puts extra stress on the joints, which can lead to damage and pain.  Infertility: Obesity can be a cause of infertility in both men and women. In men, obesity can lead to low sperm count and quality. In women, obesity can lead to irregular periods and an increased risk of polycystic ovary syndrome (PCOS). Pregnancy complications: Obesity can increase the risk of pregnancy complications, such as gestational diabetes, preeclampsia, and cesarean delivery. Mental health problems: Obesity is associated with an increased risk of mental health problems, such as depression and anxiety. Undernutrition is a condition of having too little of essential nutrients, which can lead to a range of health problems, including: Wasting: Wasting is a loss of muscle and fat tissue, which can lead to weakness, fatigue, and a weakened immune system. Stunting: Stunting is a condition of impaired growth and development, which can lead to cognitive and physical impairments. Micronutrient deficiencies: Micronutrient deficiencies are deficiencies in vitamins and minerals, which can lead to a variety of health problems, such as anemia, goiter, and rickets. Health impact of undernutrion Increased risk of death: Undernutrition is a major cause of death in children under the age of 5. In 2020, it was estimated to be the cause of 45% of deaths in children under 5 years of age. Weakened immune system: Undernutrition can weaken the immune system, making people more susceptible to infection. This is because undernutrition can impair the body's ability to produce white blood cells, which are essential for fighting infection. Increased risk of chronic diseases: Undernutrition increases the risk of developing chronic diseases, such as heart disease, stroke, and cancer. This is because undernutrition can lead to changes in metabolism, inflammation, and gene expression that can increase the risk of these diseases.  Impaired growth and development: Undernutrition can impair growth and development in children, leading to cognitive and physical impairments. Children who are undernourished are more likely to be stunted, which is a condition of impaired growth and development that can lead to cognitive deficits, reduced physical stature, and increased risk of chronic diseases. Other health consequences of undernutrition can include: Wasting: Wasting is a loss of muscle and fat tissue, which can lead to weakness, fatigue, and a weakened immune system. Micronutrient deficiencies: Micronutrient deficiencies are deficiencies in vitamins and minerals, which can lead to a variety of health problems, such as anemia, goiter, and rickets. Pregnancy complications: Undernutrition can increase the risk of pregnancy complications, such as preeclampsia, low birth weight, and miscarriage. Causes of undernutrion Malabsorption: This can be caused by a variety of conditions, including celiac disease, Crohn's disease, ulcerative colitis, and short bowel syndrome. Anorexia nervosa: Anorexia nervosa is an eating disorder characterized by an extreme fear of weight gain, a distorted body image, and severely restricted food intake. People with anorexia nervosa often have a very low body weight and may experience a variety of medical complications, including undernutrition. Bulimia nervosa: Bulimia nervosa is an eating disorder characterized by binge eating followed by purging behaviors, such as vomiting, laxative use, or excessive exercise. People with bulimia nervosa may have a normal body weight or may be overweight or obese. However, they are still at risk for undernutrition due to their purging behaviors.  Other eating disorders: Other eating disorders, such as avoidant/restrictive food intake disorder (ARFID) and pica, can also lead to undernutrition. ARFID is characterized by an avoidant or restrictive eating pattern that is not explained by another medical condition or eating disorder. Pica is characterized by the eating of non-food substances, such as dirt, paint, or chalk.  Cancer: Cancer can lead to undernutrition through a number of mechanisms, including: a) Direct malnutrition: Cancer cells can consume a lot of nutrients, which can deprive other cells of the nutrients they need. b) Cachexia: Cachexia is a syndrome of wasting and weakness that is often associated with cancer. It is caused by a complex interaction of factors, including inflammation, anorexia, and hormonal imbalances. c) Side effects of cancer treatment: Certain cancer treatments, such as chemotherapy and radiation therapy, can cause side effects that can lead to undernutrition, such as nausea, vomiting, and diarrhea.  Gastrointestinal disorders: Gastrointestinal disorders, such as Crohn's disease, ulcerative colitis, and inflammatory bowel disease (IBD), can lead to undernutrition through a number of mechanisms, including: a) Malabsorption: These conditions can damage the lining of the small intestine, which can impair the body's ability to absorb nutrients from food. b) Increased nutrient losses: Diarrhea, which is a common symptom of these conditions, can lead to increased losses of fluids and electrolytes, as well as nutrients. c) Decreased appetite: Pain, fatigue, and other symptoms of these conditions can lead to a decreased appetite, which can further contribute to undernutrition.  Chronic infections: Chronic infections, such as HIV/AIDS, tuberculosis, and malaria, can lead to undernutrition through a number of mechanisms, including: a) Increased metabolic demands: Infections can increase the body's metabolic demands, which can require more nutrients. b) Decreased nutrient absorption: Infections can damage the lining of the intestine, which can impair the body's ability to absorb nutrients from food. c) Decreased appetite: Infections can cause fatigue, malaise, and other symptoms that can lead to a decreased appetite. d) Medications: Certain medications can cause side effects that can lead to undernutrition, such as nausea, vomiting, diarrhea, and decreased appetite.  Malnutrition Malnutrition refers to an imbalance in nutrient intake. It can mean having too little of essential nutrients, known as undernutrition, or having too much, known as overnutrition. Undernutrition is more common than overnutrition, especially in developing countries