How does the metabolism work with regard to alcohol?
The subject was in a moderately fasted state when we began the experiment, and you can see the fat calories and carbohydrate calories used in the graph below. This would be a fairly typical pattern of fat and carbohydrate utilisation for a person with a standard diet and under normal circumstances.
You will notice that as the intensity of the exercise increased, the amount of fat burned falls away and the amount of carbohydrate burned increases sharply. this is because the body is not able to mobilise fat as quickly as carboohydrate, so as the body needs to increase the rate of energy production, it switches fuels to carbs for the faster release of energy.
One of the things that you see in more rigourously trained individuals and athletes, is their ability to utilise fat at even very high heart rates. At MVM we have seen people who have continued to use predominantly fat as fuel right up into the 160s and 170s Heart Rate. Of course this takes years of training to achieve this.
So what happened after the alcohol
After completing the first test, the subject was given a large glass of wine and a jam doughnut. While it might have been interesting to see the individual effects of these foods, we were limited by time, and strictly it we were to do that we would need to start with the subject in a fasted state each time, which would necessitate a multi-day experiment.
Regardless, the experiment done as it was, the results of the second test can be seen below. We can see exactly the result we were hoping for. Firstly, note how the total carbohydrate burn is reduced at all levels, even at the highest intensities. Secondly the carbohydrate burn is reduced to zero for some of the test – instead the results are showing that the body is getting all of its energy production from ‘fat’ according to the machine, but we know that this isn’t actually fat, but because fat and alcohol have the same RQ, this is actually alcohol being burned.
Beyond alcohol’s potential as a high number of calories, there are other effects which alcohol has which will impact your health and fitness journey.
Firstly, while alcohol is being turned into energy, the body has to deal with ongoing high levels of glucose in the bloodstream, which will ultimately lead to a loss of insulin sensitivity, and an increase in insulin resistance. Once insulin resistance increases, the body will tend to further put on and store more fat, so its definitely to be avoided.
A second effect of alcohol is the tendency for alcohol to cause fat to be stored around the liver. This fat, called Visceral Fat, is a particularly dangerous type of fat, for a couple of reasons.
Some studies have found that this fat can actually change the hormonal profile of the liver, and cause it to generate and store more food as fat.
Secondly, visceral fat is highly correlated with high cholesterol, including high LDLs, low HDLs, high blood pressure, and increased arterial calcification.