Introduction
Obesity is defined as an abnormal or excessive accumulation of fat that serves as a major risk factor for several chronic diseases, including cardiovascular diseases such as heart disease and stroke, causing the majority of deaths worldwide. According to recent trends, there is an exponential increase in the percentage of children and adolescents aged 5–19 years living with obesity four-fold from 2% to 8% globally, while the percentage of adults 18 years of age and older living with obesity more than doubled from 7% to 16%.
The pros and cons of anthropometry
The most common method for measuring obesity is BMI, which is calculated by dividing weight in kilograms by height in metres squared. A body mass index (BMI) above 25 is considered overweight, and above 30 is obese. BMI is used to define obesity since it is an easier and cost-effective parameter. However, the BMI may not be accurate for everyone, as it can overestimate body fat in muscular people, such as in trained athletes and underestimate it in older people or those who have lost muscle.
Body composition analysis (BCA) is a way to measure the percentage of fat, bone, and muscle in your body. It can be measured using non-invasive methods like bioelectrical impedance analysis, MRI, DEXA, air displacement plethysmography, and hydrostatic weighing, these methods are more reliable in diagnosing and tracking down the progress in the management of obesity, but all these methods are time-consuming and expensive compared to BMI, and each of these methods has its specific contraindications.
Types of fat cells
There are three types of fat cells in our body – White, brown and beige.
- White fat cells are used to store lipids in the form of triacylglycerides and release fatty acids when the body needs energy.
- Brown fat cells are predominantly found in infants which gradually diminishes with age, and helps in insulation and maintaining body temperature by non-shivering thermogenesis.
- Beige fat cells are present in adults, embedded between white fatty tissue, especially in the neck and shoulder areas. It produces heat but comparatively less than brown fat cells, also they help in using up excess energy.
Mechanism of the known beige fat cells
The previously known beige cells had a similar function to brown fat cells which are used to generate heat via a protein called UCP1, located in the inner membrane of the mitochondria through which the protons flow back into the mitochondria. Protons are electrically charged particles that help in energy conversion processes in cells generating heat from friction.
The new beige fat cells uses the “Sisyphus mechanism”
Recently an international research team has discovered a new type of beige fat cells without the UCP1 protein, and that these also consume energy and thus produce heat utilising a “Sisyphus mechanism.”
Heat is always released in all the biochemical processes that take place in cells. It involves two conversion processes; The cells break down fats into fatty acids and then convert it into new fats. On the other hand, using enzymes converts creatine and creatine phosphate, a related molecule and converts it back into creatine.
Scientists named these back-and-forth processes as “futile cycles” in which they don’t add anything to the biochemical budget overall, but they consume energy and generate heat.
Fat cells of this new beige type therefore play an important role in energy metabolism in the human body and have a positive effect on metabolic diseases, because beige fat cells convert energy into heat and help to break down the excess fat.
The new type of beige fat cells was first described in mice, later on, it was found in human adipose tissue. However, the previously known type of classical beige fat cells was present in less than half the population but the new futile-cycle type is present in almost all humans but in differing amounts.
Conclusion
The study has shown people with a high number of beige fat cells of either type tend to have better metabolic health and remain physically fit, which makes them less susceptible to obesity and other metabolic disorders such as diabetes.
The discovery of a new type of beige fat cell would embark on the future of obesity management. It may be possible to transplant beige fat cells in those people who have reduced amounts of beige fat cells in their bodies suffering from metabolic disease or obesity. It would also help in the development of new pharmacological drugs which activate the beige fat cells, which often remain inactive and could be used to treat diabetes-induced obesity or those who had already been overweight and have reduced their weight through diet, exercise ,surgery or other means. Activation of beige fat cells would help in maintaining the body weight in the long term.
Dr Yashika,
Junior Doctor, Simplyweight
