T Nation

Glycerine - count the carbs or not?

I rarely eat protein bars, but sometimes I do when I’m in a rush. I like the
new Desiner protein bars that are supposedly low carb but are loaded
with glycerine. Some people say count the “invisible” carbs by doing a
little math with the calories, some say it affects your blood sugar levels
different so don’t. I’m not on a low carb diet, just want to keep my
macronutrient levels right. Could someone knowledgeable answer this
question for me?

they have a caloric value so count them in your daily total

I use Labrada’s Lean Body bars. Its not exactly a “low carb” bar, but their not too high. The thing I like about them is that they list both the sugar and non-sugar alcohol on the label under the “carb” section, and that takes some of the guess work out.

the reason its not included as a carb is because it doesnt affect your blood sugar.

Can anyone put some science behind one of these answers? Seems like no one knows. JMB? T-mag staff? Anyone who knows for sure?

The reason most don’t comment on this with confidence is because there hasn’t been much done on the subject. Most of what has been done, has used respiratory gas exchange to estimate the contribution of glycerol to metabolism. This method is pretty simple, but is not appropriate and therefore studies that have used this approach are essentially worthless. REcently though a group out of Canada published a study that used 13C radioactively labeled glucose or glycerol to determine the level of oxidation of glycerol when administerd with glucose. They showed that glycerol was oxidized during moderate intensity exercise and provided about 4% of the energy, which was similar to the exogenously administered glucose.

The take home point to this study was that glycerol has traditionally been thought to be essentially, metabolically inert during exercise, but this is not the case. Further, it was not clear whether the glycerol was converted to glucose in the liver, or metabolized in the peripheral skeletal muscle. The exercise was performed at 70% VO2max, and at this intensity, gluconeogenesis will be minimal, therefore it was likely oxidized in the muscle. Further yet, in the absence of lipolysis associated with exercise, glycerol will provide substrate for esterification with free fatty acids in the liver, resulting in triglyceride formation. It is true that glycerol will not influence insulin levels, so, it is a better carb source on a low carb diet, but the calories are approximately 4 kcal/gram and can be oxidized, or used for triglyceride formation, so you should certainly count them.

Wow, Steve, that was a great answer! T-Mag staff, are you watching this guy?

Btw…did anyone see the designer ads promoting glycerine as …the fat burning carb…sheesh…Mike

I’ve always counted them as carbs - I have my diet spreadsheet set up so you enter calories, protein grams, and fat grams, and it automatically puts anything else in the “carbs” category. I just consider it a very low glycemic-index carb (useful for diabetics like me) and go from there.

Is that where that information about designer bars being ‘fat burners’ is coming from? Jesus, I’ve had some chick coming in the store telling me for weeks now that she read in a magazine about those bars helping to burn fat. I kept insisting to her that there was nothing in those bars that wasn’t in the other bars, but she read it so it must be true.

Its incredible how far a company will reach in order to put stuff in they’re ads.