Obesity: Causes, Impact on Adults, and Diet Solutions
Introduction:
Obesity is characterized by an excessive buildup of fat in adipose tissues. It isn’t just about gaining weight; it’s about gaining fat. This syndrome occurs when there is a considerable increase in body weight due to an imbalance in energy intake and expenditure. When more energy is taken through food than is expended through physical activity, the surplus energy is transformed into fat and stored in adipose tissues.
To better comprehend obesity, you must grasp the ‘Fat Cell Theory’.
Fat cells, also known as adipocytes, are found mostly in adipose tissue, which is distributed throughout the body. The overall number of fat cells is determined early in development to allow for fat accumulation. Fat cell count increases more rapidly in late childhood and early adolescence. Fat cells divide when they reach a certain size, and the number of fat cells may increase throughout adulthood. Obese folks have more fat cells than leaner people.
image: Overweight
WHO Classification of Weight Status
| Weight Status | Body Mass Index (BMI), kg/m² |
|---|---|
| Underweight | < 18.5 |
| Normal Range | 18.5 – 24.9 |
| Overweight | 25.0 – 29.9 |
| Obese | ≥ 30 |
| Obese Class I | 30.0 – 34.9 |
| Obese Class II | 35.0 – 39.9 |
| Obese Class III | ≥ 40 |
Check out this resource for an easy and accurate BMI calculation to assess your health and weight status. click here
1. Understanding the Leptin–Melanocortin Circuit
The leptin–melanocortin pathway in the brain plays a crucial role in managing appetite and regulating food intake. At its core is leptin, a hormone produced by fat cells, which acts like a messenger to the brain about the body’s fat levels. When fat stores increase, leptin levels rise, signaling the brain to reduce hunger. However, in obesity, the body can become resistant to leptin, similar to how it develops insulin resistance in diabetes. This condition, known as leptin resistance, blocks the brain’s “full” signal, leaving the person feeling hungry even after eating.
Leptin levels drop during fasting and increase after meals, helping regulate hunger based on energy needs.
2.Physical inactivity dramatically raises the risk of obesity via numerous mechanisms:
Energy Imbalance: When physical activity is minimal, the body burns fewer calories. If caloric intake remains constant or increases, any energy surplus is stored as fat, resulting in weight gain.
Metabolic Effects: Regular exercise improves insulin sensitivity and promotes efficient metabolism. Lack of exercise can cause insulin resistance, a condition in which the body’s cells do not respond properly to insulin, resulting in fat buildup.
Muscle Composition: Inactivity can lead to an increase in intermuscular fat (fat within the muscles), which is related with an increased risk of heart disease and metabolic illnesses.
3.Excessive Caloric Intake
Obesity was once thought to be simply a result of consuming more calories than the body burns, with the solution being to eat less and exercise more. However, this explanation is now considered oversimplified. An alternative view suggests that a high-carbohydrate diet, particularly one rich in sugar and starch, leads to high insulin levels, which promote fat storage and hinder the use of calories by muscles. This can create feelings of hunger and slow metabolism, making weight loss more difficult. On the other hand, another perspective proposes that obesity is regulated by the brain, which balances signals from hormones, the nervous system, and environmental factors. In this view, fat tissue also plays an active role in regulating hunger and energy expenditure, making obesity a more complex issue than just calorie or carbohydrate intake.
image: Eating unhealthy foods
4.Insufficient sleep
Sleep plays a key role in managing glucose levels and the body’s hormone balance. When you don’t get enough sleep, it can lead to higher blood sugar levels, lower insulin sensitivity, and decreased leptin (a hormone that controls hunger). It also raises cortisol and ghrelin levels, which increase appetite. Sleep and exercise are closely connected, as exercise helps improve sleep, and poor sleep can lead to less physical activity. One study even showed that changes in sleep duration can increase the risk of obesity by affecting fat levels and genes linked to obesity.
5.Socioeconomic status
According to studies, having a lower socioeconomic status increases the risk of obesity, particularly when accompanied with stress and emotional eating. Interestingly, in low-income countries, people with better socioeconomic position are more likely to be fat because they can purchase high-calorie foods and are less physically active. In wealthier countries, however, higher socioeconomic position is frequently associated with healthier lives, including more physical activity and better eating habits. Some countries, such as India, suffer from both obesity and malnutrition as a result of these socioeconomic conditions.
Obesity in adults can lead to several serious health complications, including:
- Impaired Glucose Tolerance and Diabetes Mellitus: Obesity can make the body less sensitive to insulin, leading to higher blood sugar levels and an increased risk of type 2 diabetes.
- Hypertension: Excess body fat can contribute to high blood pressure, which increases the risk of heart disease and stroke.
- Heart Disease: Obesity can cause heart-related issues, including coronary artery disease, due to the buildup of fatty deposits in blood vessels.
- Dyslipidemia: This condition refers to abnormal levels of cholesterol and other fats in the blood, which can increase the risk of heart disease and stroke.
- Cerebrovascular Disease: Obesity increases the risk of conditions like stroke, as it can lead to the narrowing and blockage of blood vessels that supply the brain.
- Metabolic Syndrome: This is a group of conditions, including high blood pressure, high blood sugar, and abnormal cholesterol levels, that increase the risk of heart disease, stroke, and diabetes.
- Pulmonary Abnormalities: Obesity can affect breathing and lead to conditions like sleep apnea and asthma due to excess fat around the chest and abdomen.
- Gastrointestinal Abnormalities: Obesity can lead to issues such as gastroesophageal reflux disease (GERD), fatty liver disease, and an increased risk of gallstones.
- Osteoarthritis: The excess weight from obesity puts added pressure on the joints, especially the knees and hips, leading to arthritis and joint pain.
- Reproductive Disease: Obesity can affect hormonal balance and lead to fertility problems, menstrual irregularities, and complications during pregnancy.
Cancer: Obesity is linked to an increased risk of several types of cancer, including breast, colon, and endometrial cancers.
Dietary Approach by Restriction of Macronutrients
There are 3 primary macronutrients, namely carbohydrates, fat, and protein. Carbohydrate yields 4 kilocalories (kcal) per gram, protein yields 4 kcal per gram, and fat provides 9 kcal per gram. Manipulation of macronutrient composition to aim for energy restriction as a dietary intervention has been studied extensively, and this kind of dietary intervention has been used for a long time. Even in energy-matched diets, the varying composition of macronutrients has different weight loss outcomes and overall health benefits. These different outcomes are likely secondary to differences in endocrine effects and changes in the gut microbiome that ultimately impact fat storage and body weight.
low-fat diet A low-fat diet has long been recommended for preventing heart disease and promoting weight loss. Fat provides 9 kilocalories (kcal) per gram, which made it the focus for reducing energy intake. A low-fat diet typically includes 20-25% of daily calories from fat, while a very low-fat diet contains 10-20% of calories from fat. The idea behind low-fat diets was that cutting fat would help with weight loss and improve heart health. However, recent studies show that low-fat diets are less effective for long-term weight loss compared to low-carbohydrate diets. In fact, when compared to regular diets, a low-fat diet leads to similar weight loss results as a high-fat diet. Research indicates that low-fat diets are not more effective than other dietary plans for obesity, and maintaining a very low-fat diet over time can be difficult.
image: diet
Low-carb diets: Modern diets are often high in calories and refined carbohydrates, partly due to past recommendations for low-fat diets. Carbohydrates, once seen as a primary energy source during ancient times, have earned a bad reputation in today’s world. However, the carbs from plant-based, high-fiber foods were healthier for our ancestors. In a typical American diet, 45-65% of energy comes from carbohydrates. A low-carbohydrate diet is typically defined as getting less than 45% of daily energy from carbs, usually between 52-150 grams per day. Low-carb diets are thought to promote weight loss by reducing insulin levels, which encourages the body to burn fat. Very low-carb diets, with fewer than 20-50 grams of carbs, lead to the production of ketones, a byproduct of fat burning. This approach is often part of a low-carb, high-fat diet.
The Mediterranean diet: is based on the traditional eating habits of people in countries like Italy and Greece. It includes lots of fruits, vegetables, nuts, seeds, seafood, fish, and olive oil. This diet is mainly plant-based, full of fiber, and rich in antioxidants and important vitamins and minerals. It’s lower in unhealthy saturated fats and omega-6 fatty acids, but higher in healthy fats like monounsaturated fats and omega-3 fatty acids.
The Mediterranean diet is known for its heart-healthy benefits, but it has also been shown to help with weight loss. Studies have found that when combined with calorie control and physical activity, the Mediterranean diet can lead to significant weight loss. A meta-analysis of studies found that this diet improves metabolism and reduces the risk of type 2 diabetes and metabolic syndrome compared to other diets. After 12 months, people following the Mediterranean diet lost an average of 8.7% of their weight, and those on a low-carb Mediterranean diet lost about 10%.
The Ornish diet: was created by Dr. Dean Ornish in 1977. It focuses on eating foods that are rich in complex carbohydrates and fiber, while being low in fat, especially saturated fat. The diet encourages whole, plant-based foods like whole grains, fruits, vegetables, and legumes, and avoids processed foods.In clinical trials, the Ornish diet has shown modest weight loss results. On average, people lost about 3.5% of their body weight after 6 months and 3.2% after 12 months. The diet is often combined with other lifestyle changes like aerobic exercise, strength training, yoga, and stress management for better health results.
The vegetarian diet: is becoming more popular for promoting overall health, and there are different types of vegetarian diets. A vegan diet includes only plant-based foods, excluding meat, fish, dairy, and eggs. A lacto-ovo-vegetarian diet includes dairy and eggs along with plant-based foods. A pescatarian diet allows fish along with plant-based foods.A recent study looking at 12 clinical trials found that people on a vegetarian diet lost more weight than those on a non-vegetarian diet. Among the vegetarians, those on a vegan diet lost more weight compared to those on a lacto-ovo-vegetarian diet. The study also showed that people on a vegetarian diet with calorie restrictions lost more weight than those on a vegetarian diet without calorie restrictions.
Intermittent fasting: is an eating pattern where you fast for certain periods and eat within specific windows, helping reduce calorie intake. This can lead to weight loss, better blood sugar control, and lower risks of high blood pressure and heart disease. Fasting helps burn fat, reduce inflammation, and protect against diseases like Alzheimer’s. It may also improve insulin sensitivity and metabolism. Compared to strict calorie cutting, intermittent fasting could be easier to stick with long-term while offering benefits like slowing aging and improving overall health.
Reference:
https://www.ncbi.nlm.nih.gov/books/NBK551660/figure/article-35266.image.f1/
