"Comparing yourself to others is an insult to the god within you." - Dr. Vasant Lad
Fat. Perhaps no other health topic generates as much interest and controversy as a discussion related to weight. More so than any other aspect of our body, cultural and personal attitudes toward fatness run the gamut, viewed by some with scorn, disgust, or a reflection of self-discipline, whereas for others it may be a measure of beauty and health. We are told that fat makes us sick and carries the certainty of an early death. And because fatness is hard to hide, it makes us vulnerable to judgment and moralization, attracting unsolicited advice from others who feel compelled to help, even when we are not in distress. Our societal disdain of fatness has morphed into a moral panic fueled by headlines that repeatedly reference an “epidemic of obesity”. And a fear of fat leads many to pay thousands of dollars over a lifetime to lose weight—even when they are otherwise healthy. But the vitriol hurled at fat is misguided and obscures the important role it plays in our evolution; fat is an integral part of what makes us human. It is because of fat that we evolved into the homo sapiens we are today; fat is what fueled our ability to travel the globe, make advanced tools, and thrive in complex environments that were unimaginable to our long-ago relatives. Without fat, we would not be the species we are today.
Our culture regards fat as an aesthetic nuisance, an inert slab of gelatinous tissue layered just under the skin that needs constant monitoring or it will grow with every excess calorie we consume or workout we skip. But fat—which is more accurately referred to as adipose tissue—is anything but inert. It is a complex neuroendocrine organ that serves a role as a sophisticated warehouse for our body’s energy reserves. Compared to the logistics necessary to operate an Amazon warehouse, adipose tissue is infinitely more complicated. It not only stores our fuel, but communicates with the liver, brain, and muscles about the changing energy needs of the body. We are now only starting to fully understand how this tissue works and how it becomes dysregulated, as well as the important role it plays in our health. We do know that adipose tissue is programmed for one distinct mission—to keep us from starving—and throughout our evolution has developed some amazing adaptations that we do not yet fully appreciate or understand.
For many years scientists understood that the body’s fuel was stored as droplets of fat in cells that were interlaced into a neat layer located under the skin. Technically known as adipocytes, fat cells were considered inconsequential—just blobs of lipids that were held in storage until they were needed for energy. That all changed around 1994 with the discovery of leptin, a hormone that adipocytes make to communicate with the brain. Once released into the bloodstream, leptin travels to the brain and binds to specific receptors that initiate several highly sophisticated reactions. The discovery of leptin surprised scientists, shifting their view of fat as an inert blob of fat to that of an active participant in the regulation of energy. Leptin opened the door to further research showing that adipose tissue was a highly sophisticated organ that not only sent messages to the brain, but capable of communicating directly with the liver, our muscles, and other tissues. No longer an inconsequential storage bin of calories, we now know that adipose tissue plays a key role in the regulation of hunger, satiety, metabolism, as well as a host of other hormonal reactions.
Humans evolved to be fat, and, in doing so, gained an evolutionary advantage that enabled us to thrive and populate the entire planet. Compared to other primates, humans store high levels of fat. Whereas the average primate has about 5 – 8% of body fat, lean women carry between 15 – 25% fat, while lean men carry 10 – 15%. The difference in fat levels between humans and primates has nothing to do with diets or physical activity; our higher fat levels reflect the incredible energy needs of our bigger brains. The complexity and size of the human brain comes at a higher energy cost than the smaller brains of our primate relatives; at rest, 20 – 25% of our energy needs go to the functioning of the brain. If it were not for adipose tissue, humans could not have survived, as the energy demands of our big brains require a tremendous caloric load. Without fat, humans would have been required to eat constantly to maintain the glucose levels necessary to support the brain’s basic functions. Storing higher levels of fat is a brilliant adaptation that allows us to carry sufficient energy, which is released slowly to maintain a steady supply of glucose for the hungry brain. Enhanced fat storage made our species more resistant to starvation, giving us an edge in survival as well as the freedom to explore and expand into uncharted territories.
Fat cells are highly efficient receptacles for the body’s energy needs. Starting in infancy and continuing into adolescence, the body establishes both the size and number of fat cells we will maintain throughout our lives. There is some turnover in adulthood, as about 10% of fat cells die and are replaced with new ones, but their numbers remain fairly constant in adulthood. Fluctuations in weight do not reflect a change in the number of cells, but, rather, their size; weight loss is a result of the shrinking of fat cells. Some research suggests this may be why it is so hard for some people to maintain weight loss, particularly when pounds are shed quickly, such as what happens with very low-calorie diets. Fat cells are programmed to maintain their size, so they are especially sensitive to changes in cell volume. Rapid shrinking of fat cells stimulates a stress response in adipose tissue as it thinks the body is starving. As the cell shrinks, leptin levels decrease, which results in distress signals being sent to the brain, telling it to downshift our metabolism and stimulate hunger in an effort to get us to eat more and refill the cell. Adipose tissue is very efficient and tenacious; dieting puts us in a battle with its drive to keep us alive. Studies have shown that gradual changes in cell volume are less likely to trigger the alarm, which is why more modest and slow weight loss over an extended period of time is easier to maintain.
Described by scientists as looking like a beach ball with a fried egg on top, fat cells are simple structures—the egg is the nucleus and the beach ball is the cell membrane. Inside the cell is a droplet of fat, also referred to as a lipid molecule. The cell gets smaller when the fat is released for energy and fills back up when excess energy is converted into fat and returned to the cell. Adipose tissue is very skilled at storing and releasing energy, but their cells have limits to the amount of lipids that can be safely stored. When fat cells exceed their storage capacity, they leak, sending the lipids to other cells in the body that are not equipped to warehouse these goods. The spillover can go into the bloodstream where it lodges on the blood vessel walls, or into heart muscle, the pancreas, and liver. Since these areas are not equipped to store fat, the chronic diseases that are related to being overweight--heart disease, high blood pressure, diabetes, and some cancers—start to take hold. Regulation of our energy needs is a precise and exacting science for which adipose tissue is well suited. Send the fat to a different type of cell and it will eventually cause disease. Just as anyone in business knows, outsourcing highly specialized work is always a gamble, and in the case of fat, it is one in which we typically lose.
Contrary to what you may hear or read, fatness, by itself, is not unhealthy, provided the fat droplet stays in its proper storage unit, safely contained and monitored within the sophisticated warehouse of our adipose tissue. Studies continue to show that it is the storage of fat in metabolic organs such as the liver and muscle that increases our risk of diabetes, metabolic syndrome, and possibly other cardiovascular diseases. This may explain why an obese person can show no signs of chronic disease whereas someone of normal weight has high blood pressure and diabetes. But this knowledge does very little to change the rhetoric that swirls around weight and health. Those in the medical community as well as allied health continue to judge and marginalize larger people, perpetuating societal fears of being fat.
The more we learn about the role adipose tissue plays in energy regulation, the more we realize that weight doesn’t always create health problems, nor is it a ticket to an early death. There are at least 5,000 genes and 37 different hormones involved in weight regulation, including the number and size of our fat cells, metabolism, hunger, satiety, and the emotional impact food has on our cortisol levels. All these variables make it impossible to know exactly why someone is a certain weight. Even so, many of us feel completely justified telling a person what they “should” weigh. And while there are several chronic conditions that can be prevented with lifestyle interventions, such as exercise and arthritis, we only seem to preach about one, and that is being overweight.
What happens when you realize that fat is not your enemy, but rather a close ally that supports you through life? Some think that befriending fat opens the door to obesity, and that only by demonizing fat can we control the progression of chronic diseases. Certainly, gaining a significant amount of weight puts us at a higher risk of disease, but there is a great deal of variability in determining our individual tipping points. Making fat an enemy puts us at war with an organ that is vital to our survival. As any dieter knows, willpower is never enough to conquer the strong drive of our fat tissue’s need for survival. Rarely are we smarter than the inherent wisdom of the body; health can only be achieved when we live in harmony with our physiology.
If you are of a more practical nature and all this talk of making peace with fat seems vague, I encourage you to stay tuned throughout November. Now that you’ve been introduced to adipose tissue, we’ll look at the role exercise plays in that elusive process called metabolism, and the impact inflammation, sleep, and stress have on adipose tissue and energy regulation. My hope is that you will enter the holidays armed with a greater appreciation of the complex processes associated with how we manage our energy. Rather than stress about love handles, jiggly arms, or curvy hips, or punishing ourselves for stress eating or skipping a workout, let’s try instead to be amazed at the complexity of adipose tissue and its important role in making us human.
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