Study: Equal Glucose And Energy Production On Low-Carb Or Low-Calorie Diet

Dr. Jeffery Browning studied glucose distribution on low-carb

Whenever an honest discussion of low-carbohydrate diets comes up within the realm of science and medicine, invariably two common points of disagreement with them arise: 1) your body can’t get enough energy to sustain itself in the absence of carbs from your diet and 2) you are causing damage to your liver. Both of these are simply red herrings in the greater debate about what constitutes a truly healthy diet. While much of the focus on livin’ la vida low-carb has been on weight loss over the years (which it works VERY well in producing), the real benefit that this way of eating affords people is how well it works with the natural functions of the body to produce tremendous health results.

For more than three decades, we’ve been told by the media and those so-called health “experts” in America to simply cut our fat and all of the weight and health problems we have will just disappear. Unfortunately, what has happened is all that fat has been replaced with something even more despicable–CARBOHYDRATES! Not surprisingly, obesity rates are up astronomically and metabolic diseases that once seemed unheard of have become the norm. Things like non-alcoholic fatty liver disease (NAFLD) which can lead to inflammation, fibrosis and cirrhosis have all been brought on by this increase in carb intake, but it’s been difficult to confirm this association to this point. But now we have a new study that provides even further evidence of this undeniable fact about what carbs are doing to our bodies.

Lead researcher Dr. Jeffery D. Browning, assistant professor of Internal Medicine in the Digestive and Liver Diseases department at the University of Texas Southwestern Medical Center, wanted to understand the mechanism behind how glucose is made by the liver (what is referred to as “hepatic energy production”) on a variety of different dietary approaches. To do that, Dr. Browning measured the amount of glucose made by the liver in 14 study participants at varying BMI levels (ranging from 25-35) whose weight was kept stable during the 14-day study.

They were split up into one of two groups:

CARBOHYDRATE-RESTRICTED or
CALORIE-RESTRICTED

Dr. Browning attempted to balance out the two groups by having matches for age, BMI, gender and ethnicity on both sides. Additionally, he recruited another seven study participants with a BMI less than 25 (defined as “lean” in the study) for a weight-stable comparison control group to the two primary groups. The control group ate their regular diet while the two study groups either ate low-carb or low-calorie depending on their assigned group.

All of the study participants were metabolically analyzed overnight for the researchers to assess how much glucose the liver was actually making on its own apart of what is consumed in the diet. In the control group of lean study participants eating their own diet, the significant amount of carbohydrates they were consuming allowed the TCA cycle (aka Krebs cycle) to produce enough energy from glucose.

However…

“This was not the case in individuals undergoing carbohydrate restriction,” the researchers stated.

Those in the CARBOHYDRATE-RESTRICTED group saw an INCREASE in the production of glucose by the liver through gluconeogenesis, where the body can make its own carbs from the protein consumed in the diet. This is why even in the absence of a significant amount of carbohydrates the body can still function at a high performance level–something the researchers took note of.

“This suggests that in fasted human subjects undergoing weight loss, the elevated gluconeogenesis associated with carbohydrate restriction is driven by substrates such as lactate or amino acids,” the researchers explained.

Even still, the TCA cycle in the CARBOHYDRATE-RESTRICTED group was virtually identical to the CALORIE-RESTRICTED group which means the rate of energy generation was the same. In other words, there was no energy drop off by those study participants consuming less carbohydrates since the liver was producing ample amounts of glucose through gluconeogenesis. That’s right, although less carbs were consumed, the amount of glucose produced by the liver made up for the deficit in the diet in the CARBOHYDRATE-RESTRICTED group.

“This observation is reminiscent of ‘hepatic autoregulation’ by which endogenous glucose production remains unchanged in the setting of altered gluconeogenesis or glycogenolysis because the two pathways tend to compensate for each other,” the researchers reported.

That’s just a fancy way of saying that whether you get your carbs from your diet or through gluconeogenesis in the liver, the body will have the necessary glucose it needs to provide the energy it needs to function. Unfortunately, the researchers did not measure ketone body production or fatty acid delivery to the liver, so the clarity of their findings were somewhat constrained because of this.

“We have shown that the sources from which endogenous glucose is produced are dependent upon dietary macronutrient composition,” the researchers concluded.

And on a CALORIE-RESTRICTED diet where the carb intake is higher, the glucose for energy comes from the carbohydrate. But on a CARBOHYDRATE-RESTRICTED diet where the carb intake is significantly reduced, the glucose for energy comes from gluconeogenesis–a basic natural function of the liver. Interestingly, biochemistry professor at SUNY Downstate in Brooklyn, NY Dr. Richard Feinman said in my podcast interview with him earlier this year that just about everyone experiences some level of gluconeogenesis overnight while they are sleeping because those hours of fasting cause the body to revert to providing glucose when all of the carbs consumed are used up. So anyone claiming that gluconeogenesis is somehow harmful or dangerous to the body has some explaining to do since we all experience it from time to time whether we are restricting our carbohydrates in our diet or not.

Dr. Browning and his research team said their study results show great promise for those people suffering from non-alcoholic fatty liver disease (NAFLD) primarily from the improved disposal of fat in the liver. They added that this shows a rather direct correlation between carb consumption and the severity of NAFLD, something I’ve blogged about before and low-carb researcher Dr. David Ludwig has publicly warned about for years. How many more studies is it gonna take for this message to FINALLY stick?

These results of this study are published in the November 2008 issue of the scientific journal Hepatology. You can e-mail Dr. Jeffery Browning about his research at Jeffrey.Browning@UTSouthwestern.edu.