People with Type 2 diabetes have been found to have better blood sugar control after gastric bypass surgery than with diet alone–even if the same amount of weight is lost. A recent study published in Science Translational Medicine attempted to understand if something other than weight loss was contributing to better management of blood sugar.
Based on animal studies, it is suspected levels of branched-chain amino acids (BCAAs) and fatty acylcarnitines are higher in patients with insulin resistance . So researchers looked at these levels in plasma from morbidly obese patients with Type 2 diabetes who had lost 10 kilograms with either gastric bypass surgery or a strict diet.
They found levels of both were decreased in the gastric bypass patients within a month but not for those who lost weight with diet. Even after two months, the diet patients had little or no change in these levels.
This led researchers to conclude mechanisms other than weight loss contributed to better blood sugar control and something about the gastric bypass surgery itself helped to improve control. It was unknown whether the lower BCAA and acylcarnitine levels were the cause or consequence of the improvement.
BCAAs make up as much as 25% of the amino acids in dietary protein, and are found to be elevated in diets high in animal protein. People who are obese tend to have higher BCAA levels than those who are not obese.
Acylcarnitines are the result of incomplete or inefficient oxidation of fat. Higher levels are felt to be an indicator or biomarker of prediabetes and Type 2 diabetes. This is because incomplete oxidation of fats has been found to occur in these conditions.
In a 2009 study using rats, researchers concluded insulin resistance was caused by a high-fat diet. They also discovered insulin resistance developed with a high BCAA intake but only if there is also a high fat intake (even though this group ate less). They also found a moderate fat intake did not cause insulin resistance in the test subjects.
What Can be Learned From This?
As stated, it is not clear whether the decreased levels were the cause of consequence of better blood sugar control. Regardless, we should watch our fat intake. According to the researchers, they did not feel a moderate fat intake caused insulin resistance. They also did not feel BCAAs (high in animal protein) were harmful by themselves, but when combined with a high fat intake and eating beyond energy needs. So, in other words, if you are already eating a lot of animal protein, you might want to reconsider a lot of additional fat.