Transcript: The Spillover Effect Links Obesity to Diabetes
Free fatty acids, meaning free fat circulating in the bloodstream not packaged into triglycerides, result in inflammation, toxic fat breakdown products, and oxidative stress, which can gum up the insulin receptor pathways and lead to insulin resistance in our muscles. And insulin resistance is what causes prediabetes and type 2 diabetes.
As the level of fat in the blood rises the body’s ability to clear sugar from the blood drops. Where does this fat in our blood that's wreaking all this havoc come from? It comes from the fat that we eat, and from the fat that we wear.
The number of fat cells we have stays constant in adulthood. It’s interesting; the way they figured that out is by measuring the amount of radioactive carbon trapped in our DNA from all the nuclear bomb tests. Anyway, after massive weight loss, our fat cells shrink as they offload fat, but the number stays the same. Conversely, when we gain weight, our fat cells just stretch as we pack more and more fat into each individual fat cell. So when our belly, butt, or thighs get big, we’re not adding more fat cells; we’re just cramming more fat into each cell. At a certain point, our cells become so bloated that they spill fat back into the bloodstream.
This is an illustration of the so-called spillover effect. Not only does an obese person have more fat on their body, but they’re constantly spilling that fat into their bloodstream. So that could be the link between obesity and diabetes. Fat is spilling out from our fat cells and gets lodged in our muscle cells, leading to the insulin resistance that promotes the onset of type 2 diabetes.
Or the fat can enter our bloodstream through our mouth. If you put people on a low-carb diet, fat builds up in their muscles within two hours, compared to a low-fat diet, and insulin sensitivity drops. And the more fat in the muscle, the lower the ability to clear sugar from the blood. It doesn’t take years for this to happen; just hours after fatty foods go into our mouths, our bodies have problems using insulin. A fat-rich diet can increase fat in the blood, and this increase is accompanied by a decrease in insulin sensitivity.
Studies clearly demonstrate that fat in the blood directly inhibits glucose transport and usage in our muscles, which is responsible for clearing about 85% of the glucose out of our blood. These findings also indicate an important role of nutrition, particularly increased consumption of fat, for the development of insulin resistance.
Normally we have only 10 to 50 micromoles of free fat floating around in our bloodstream at any one time, but those who are obese are constantly spilling fat out into their bloodstream. But we can reach those same levels in our blood eating a high-fat diet. So a skinny person eating a low carb diet can have the same level of fat in their blood as obese people do. Similarly, being obese is like eating some horrible bacon-and-butter diet all day, because obese persons are constantly spilling fat into their bloodstream no matter what goes in their mouth.
To see any graphs, charts, graphics, images, and quotes to which Dr. Greger may be referring, watch the above video. This is just an approximation of the audio contributed by Katie Schloer.
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