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Why do we get fat?

We have heard that eating too much and exercising too little causes obesity, however our bodies are designed in a way that nothing is left to chance. Contrary to what most people believe, long term weight loss is not simply about cutting a few calories here and there. Suppose we eat equal amount of calories from a doughnut or a salad, the body will have a different metabolic response to use the calories from these foods and the hormonal responses will be completely different. Therefore medical science is coming to a conclusion that obesity is mainly a hormonal, not a caloric, imbalance.

Every single body process is a tight orchestration of hormonal signals. Whether our heart beats faster or slower is tightly controlled by hormones. Whether we feel hot or cold is also controlled by hormones. Whether the calories we eat are burned as energy or stored as body fat is also tightly controlled by hormones. So, a major factor for obesity is not the calories we eat, but how our hormones respond to the food intake. Many hormones such as insulin, leptin, thyroid, mTOR, cholecystokinin influence our appetite, metabolism and body fat distribution. People who are obese have higher levels of these hormones which encourages changes in metabolism and the accumulation of body fat. For example, insulin levels are almost 20 percent higher in obese patients and these elevated levels are strongly correlated to important areas of such as waist circumference and waist/hip ratio.

Obesity and leptin

The hormone leptin is produced by fat cells and is secreted into our bloodstream. Leptin reduces a person's appetite by acting on specific centres of their brain to reduce their urge to eat. Because leptin is produced by fat, leptin levels tend to be higher in people who are obese than in people of normal weight. However, despite having higher levels of this appetite-reducing hormone, they develop what is called as leptin resistance and their brain doesn’t sense that they are full. Thus such people tend to over-eat.

Obesity and insulin

Insulin, a hormone produced by the pancreas, is important for the regulation of carbohydrates and the metabolism of fat. Insulin stimulates glucose uptake from the blood in tissues such as muscles, the liver and fat. In a person who is obese, insulin signals are sometimes lost and tissues are no longer able to control glucose levels. This leads to abnormal accumulation of fat in the body and finally to the development of metabolic syndrome and type II diabetes.

Obesity and Thyroid

Low levels of thyroid hormone slows the metabolism and often causes weight gain. Thyroid hormone is involved in the regulation of metabolic rate and it also plays an important task in the temperature regulation in our body. It also has significant role in our food intake and burning of the body fat.

Once we understand that obesity is a hormonal imbalance, we can begin to take effective action to support a healthy body weight. The key to combating obesity is to help the body by lowering insulin. Current attempts to blame the obesity epidemics worldwide on increased availability of calories have not helped us get rid of the obesity epidemic. Consequently, many research efforts are now focused on harnessing the body's hormone system to treat obesity and obesity-associated diseases. The most promising that seems right now is to decrease the insulin levels and reverse their insulin resistance. There seems to be evidence to support this.

The following two methods seem to give miraculous results:

1. Cutting down on sugar, refined carbohydrates and restricting our carbohydrate intake

2. Increasing the time period in our meal timings so that the spike of insulin does not occur frequently.

Such long-term behaviour changes, healthy eating and regular exercise, can re-train the body to shed excess body fat and keep it off.

Dr Deepti Arora, Physician & Diabetologist

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