You have heard that having too much body fat can be unhealthy. But how much is too much? The answer is “it depends.” You might know someone who has diabetes or high blood pressure without very much excess fat. Or you might know someone who has a lot of excess body fat but no current metabolic diseases. Why is that? Body fat storage can be a complicated issue.
It is not the amount of fat that leads to metabolic disease. Often, it is the health of that fat, and how well it can do its job. Without well-functioning fat tissue, fat builds up in other vital organs outside the fat cells. Fat stored in vital organs is toxic to those organs and is at the root cause of many metabolic health issues
Fat Tissue Does More than Store Energy
You may see fat as an enemy—something that bothers you, that you want to get rid of. However, fat is part of your body for a reason! It has many important jobs to do.
Energy can be stored in many ways, but storing it as fat has certain advantages. Fat tissue is the ideal place for fat to be stored, and insulin is the hormone that puts it there. Because fat stores are such a vital part of a healthy body, fat tissue uses hormones to communicate with the rest of the body about how much fat it has stored to help regulate energy storage throughout the body. These hormones are involved in regulating insulin sensitivity, appetite, and metabolism.
Sometimes Fat Tissue Fails
Fat tissue can only hold so much fat. When fat tissue gets too full, it becomes insulin resistant and stops storing new fat. Since the fat has nowhere to go, it ends up in other vital organs like your liver, pancreas, heart tissue, and skeletal muscle. Those organs are not made to store fat, and it interferes with their ability to function. They too become insulin resistant, among other issues.
To put the brakes on storing more fat once capacity is maxed out, fat tissue sends out “SOS” signals that also cause damage. These signals are hormonal and increase inflammation, change the sensitivity of your appetite regulation, and do even more to promote insulin resistance.
When Does Fat Tissue Fail
When fat tissue is overloaded, it is bad news for the rest of the body. Scientists aren’t entirely sure what determines someone’s fat tissue storage capacity and at what point fat tissue starts causing health problems. The point at which this happens varies greatly from person to person.
As a general rule, the more fat you have, the more likely your fat tissue might be overloaded and cause health problems. Body Mass Index (BMI) is a decent, easy-to-determine indicator of how much body fat someone has in excess of what is healthy. Calculate yours here.
But for some people, fat tissue “overload” happens at lower weights and lower total body fat percentages. So, it is possible to have a fairly healthy BMI, but your fat tissue is still overloaded. This often happens when someone has fat collected in their belly or abdominal region.
Belly fat is a sign that someone has fat build-up in their vital organs that reside in the abdominal region. Waist circumference is a good measure of this. Having a waist circumference over 35 inches for women or 40 inches for men is considered a risk factor for metabolic health issues, regardless of BMI status.
When Does Fat Tissue Fail
Once you understand how all this works, it becomes very intuitive that even a small amount of fat loss can improve metabolic health. In fact, losing just 5% of your body weight is associated with improvements in blood pressure, insulin sensitivity, and cardiovascular disease risk markers like cholesterol and triglycerides. That is just 10 pounds for someone with a weight of 200 pounds.
Fat loss eases fat tissue “overload” and improves the function of fat. When fat functions better, the whole body functions better. Since the issue is central to fat tissue, it is fat loss—not just general weight loss—that creates this effect on health.
Emily Dhurandhar, Ph.D.
Chief Scientific Officer