Thursday, January 17, 2019

Measuring Metabolism

I don't usually write about commercial products, but this one seems interesting . . . if it fulfils its promise. It's a way of determining whether you're burning primarily carbohydrate or fat.

This is done by calculating something called the respiratory quotient (RQ), which is the ratio of carbon dioxide production to oxygen consumption. An RQ of 1 means you're metabolizing mostly carbohydrate, and an RQ of 0.7 means you're burning mostly fat. Obviously, numbers between these extremes indicate you're burning both. Protein has a small effect on the RQ.

When I was in a clinical study at the Joslin Diabetes Center some years ago, they measured my RQ. I had a big hood over my head for what seemed like a long time, and it was horrid when my nose started to itch but I couldn't scratch it.

Now an Israeli company has produced a little gizmo into which you breathe, and they say it will give you an RQ. It's not cheap (about $300), and it won't be available until next August, although you can order it now for $249. Last summer, articles were saying it would ship in February 2019 and preorder price was $179. I've seen a lot of gizmos being announced that never come to market, so I'll believe this one when I see it. Nevertheless, it's interesting.

So why would you care what your RQ was? Well, we can all be a little different, and some people may be better at burning carbohydrates or burning fats. Let's say you want to lose fat. When your carbohydrate intake, and hence your insulin level, is low, your hormones can help you break down the fat in your fat cells and ship fatty acids out into the circulation to be taken up and burned by tissues that need energy.

But if you don't burn the fatty acids very efficiently they'll just stay around and eventually may get taken up by the fat cells for storage as (ugh) fat.

It would be interesting to measure the RQ of someone just starting a low-carb diet and then keep measuring as the person became adapted to the diet. Would the RQ show more fat oxidation as time went by and the body became accustomed to using fat for energy? Could the RQ be shown to be related to the fatigue some people feel when going on a low-carb diet?

Some people are more efficient at fat burning than others. Could they determine this by measuring the RQ with this gizmo

If despite limiting carbohydrate in your diet, the gizmo showed that you were still getting a lot of your energy from carbohydrate, you would know that you had to limit carbohydrate more than some other people.

Of course the gizmo could also be used by people who wanted to burn a lot of carbohydrate.

I look forward to the day when this is actually available to see how people are using it.


  1. I wish I had one of those right now! I was very sick with Crohn's disease last year and lost almost 30 pounds (and ended up in the ER with a badly infected perirectal abscess). My next A1c was my lowest in years (mid 5s) and my doctor cut my glipizide in half to 2.5 mg a day. I was very worried because my carb intake skyrocketed with my new Crohn's friendly diet (featuring white bread and white rice!) but so far my bg readings have been lower than what they were before the Crohn's diagnosis. Maybe my metabolism has changed - and if it has, I would love to be able to monitor it!

  2. Why don't you contact them, explain your situation, and ask if they need any more beta testers.

  3. Unfortunately, my luck ran out quickly - a home A1c test in December showed I was already at 7 (up from 5.7 within less than two months) so I went back to 5mg of glipizide and last week it was back to 6. Not great, but I'm very relieved. I'm still not sure what the cause/effect is with so many variables, but now I've gained back 18 pounds and I'm cutting back on the carbs again, which isn't easy once you're used to rice and potato salad again!

    1. I'm sorry. We have to remember that diabetes never goes away completely. If we return to eating rice and potato salad, we'll probably put on weight and BG will be higher.

      I no longer want potato salad, but if you do, Fran McCullough has a great recipe for "potato" salad in her book "The Low-Carb Cookbook."

      I realize balancing diabetes and Crohn's is a challenge. You can do it!