"The Inside is What Counts"
"The Inside is What Counts" The ides that "the inside is what counts" may not be an old wives tale, as a new study shows that people who possess a large amount of white fat on their bodies are more likely to live longer. This is in contrast to those with high cholesterol, which poses more risks for heart disease and development of diabetes. Meanwhile, those with high levels of brown fat (which regulates body temperature) were found to have stronger immune systems and lower blood pressure!
This article aims to explore the reasons why these findings are surprising and informative for future health research about obesity.
"The Inside is What Counts"
In the movie Her, Joaquin Phoenix's character turns out to be kind of sweet, smart and funny underneath all that ego. This discovery was one in a long line of similar observations in science. The idea that "the inside is what counts" has held true for centuries and can be seen as a scientific version of the old wives' tale: "A watched pot never boils." While seemingly an idiom, it actually applies when it comes to the forces that drive our bodies. So how does science explain why inside matters? The exterior part of our bodies, called our "exoskeleton", is controlled by hormones and other external factors like sun and water (1). The inside, however, is the control center of our bodies. It houses all the vital organs that allow us to live and survive. This includes our brain, heart, lungs and liver (1). The body's inside is a closed ecosystem and therefore under constant supervision by the immune system. If any potential issue appears in the body's inner workings, it responds with internal surveillance units to maintain balance and health.
While it sounds complicated, you may not have given this much thought in your own life! For example, you might know intuitively that more fat on your outside doesn't equate to more fat on your inside (2). But how much do you know about fat and its role in your body? And what does our exploration into the distinctions between the inside and outside of our bodies tell us about obesity?
Traditional definitions of obesity are based on Body Mass Index (BMI), which is calculated by a person's weight (in kilograms) divided by their height squared (in meters)(3) . While BMI is an effective tool for public health researchers to study obesity, it does not accurately measure body fatness, because it uses only a person's weight and height. As we know, muscle tissues have greater densities than fat tissues. This means that muscle tissues weigh more than fat tissues. In addition, muscle tissues are more metabolically active than fat tissues. So, although muscle tissue and fat tissue have similar densities (4), their relative metabolisms can differ substantially . In essence, BMI does not measure a person's body fatness (5).
A better way to determine obesity is to measure total body fat by using dual-energy X-ray absorptiometry (DXA) or ultrasound imaging(3). With that method, researchers can measure the amount of skeletal and subcutaneous fats and soft tissues in different areas of the body. DXA uses a machine that emits electromagnetic waves and measures the absorption of these waves at different parts of the body. Ultrasound is not as accurate a method as DXA, but it has been widely used to evaluate body composition (6).
So now that you know what indicators are currently used to measure obesity, let's see if "the inside is what counts" in our bodies. This is where the new study by researchers from the U.S. Department of Energy Joint Genome Institute comes in! The researchers extracted DNA from fat tissue samples and sequenced the genome sequences of more than 70 different types of fat found on different parts of the body. They also used a technique called RNA sequencing to make sure that the DNA came from fat tissue cells before analyzing the genome sequences (7).
What they found was a pattern. In the white fat tissue samples, the genome sequences all pointed to the fact that they belonged to a specific type of cell called adipocytes. Adipocytes are fat cells that accumulate many fatty acids in their mitochondria, which produces energy for the tissues (8). So the adipocyte's genome is regulated in a way similar to skeletal muscle tissue, which also has a high density of mitochondria. Adipocyte's genome is also regulated by fat-based hormones called lipokines such as adiponectin and leptin (9).
Now let's take a look at brown fat, or thermogenic fat. This type of fat is found around the neck and collar bone area, and it uses mitochondria that produce heat instead of energy (10). This type of tissue can be found in newborns and hibernating animals (11). In humans, the brown fat tissue is most active when a person is sleeping.
Maintaining body temperature can be important for life preservation, so scientists have identified a protein in brown fat called UCP-1. UCP-1 increases the body temperature by increasing ATP production, which also stimulates energy metabolism (12). You can see from this example that the brown fat is also regulated by a hormone called irisin. Irisin is released by muscle tissues and stimulates brown fat cells to burn more energy (13).
So let's recap. White fat cells are similar to muscle tissue, but brown fat cells are similar to the brain. This means that the white fat cell DNA may have similarities with skeletal muscle tissues and those with high levels of white fat have ample energy reserves. In contrast, those who have high levels of brown fat look out for their health! They seem to be more aware of their own bodies and internal processes. They know when and where to shed some pounds!
So now we've established that, "the inside is what counts". This means that those who have a lot of body fat from external sources, such as food, are using their energy reserves. So it's going to be hard for them to lose weight. However, if you're reading this article in the wintertime, it might be a good time to take a closer look at your internal process! Are you more active than usual? Are you drinking more water? Do you feel warmer than usual? Or are you just looking out for your health in general?
Conclusion
Our body is a closed ecosystem that is monitored by internal surveillance units. We have learned from this article that the information we get from external sources such as clothing, skin and weight cannot be used to determine our inner workings. Instead, it is up to us to keep an eye on our health on a day-to-day basis. By taking note of our bodies' behaviors, we can get a more accurate picture of what's going on inside!
References:
1) Keith R, Wu X, Colvin RA, Dilks JW and Johnson MA. How Does the Body Keep the "Inside" and "Outside" in Different States? Frontiers in Biology Portals 2012; 2: 1– 9.