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.

Friday, January 11, 2019

Connected Systems

Everything is connected.

No, this won't be a New Age rant on oneness with the universe. I'm speaking of the various systems in the body, which used to be put into boxes as if they operated on their own. There was the circulatory system, the nervous system, the respiratory system, the digestive system, and so forth, and many doctors specialized in one system or another.

Different processes were thought to take place in different systems. For example, gluconeogenesis (the formation of glucose from other compounds) was said to take place in the liver, and although it was mentioned that the kidney also performed some gluconeogenesis, this was mostly ignored. This approach made sense in the past, when measurement techniques were relatively crude, but today techniques have improved and it's even possible in some cases to measure what's going on in single cells.

So now, more and more, we're learning that the various organs have roles other than the main roles that have been known for decades, and the various systems are interconnected, sometimes in surprising ways. For example, not long ago, fat was considered just a way to store extra energy. It's now well known to secrete hormones too.

One recent study showed that a gut hormone interacts with brown fat to tell the brain that it's time to stop eating. The hormone, secretin, has been known since 1902, but its role was said to be to stimulate the pancreas to release bicarbonate to neutralize the acids coming from the stomach. Now it seems it has at least one other role. Mice injected with secretin had less appetite and increased the amount of heat the brown fat produced. Unless you're cold, heat is "wasted" energy, so increasing the amount of heat produced would mean they would gain less weight from the food they ate.

And a study of mast cells also revealed unexpected effects. Mast cells produce histamine, which is important in causing allergic symptoms, so many allergy sufferers take antihistamines. This study showed that histamine that goes to the liver, not the lungs or nose, also helps regulate ketogenesis (the production of ketone bodies from fatty acids).

It does this via a molecule called OEA (oleoylethanolamide). Previously, researchers thought OEA's role was to block hunger pangs. It does, but it also stimulates ketogenesis.

These complex interactions are one reason different people can react differently to various medications and diets. One person might have a difference in the mast cells and another might have a difference in the sensitivity of the liver to histamine and another might have a difference in some related but as-yet-unknown reaction in the same system. (I'm using the term "difference" rather than "defect" because sometimes a metabolic difference that is detrimental in one environment turns out to be beneficial in another.)

Hence we should never assume that what works for one person will work for us. Today we have so many tools to measure the various aspects of our diabetes that we can try something and then if it doesn't work try something else. No one diet or one drug or one exercise regime is best for everyone.

And we should remember that everything is connected. We shouldn't focus on just one system in our body and ignore the rest. They all talk to each other, and maybe healing an ingrown toenail will help our diabetes.

Tuesday, January 8, 2019

On Eggs

Recommendations on eggs seem to go from one extreme to the other, or "yo-yo egg advice."

In the 1950s and 1960s, eggs were considered healthy. Adele Davis, a popular health food guru in those days, had a chapter in her book Let's Cook it Right titled "Serve Eggs and Cheese Daily."  She went on to note that in addition to their protein content, eggs contain a lot of vitamins and minerals, which she discussed.

Then came the low-fat fad, in which any kind of fat was considered poisonous. Egg yolks, which contain a lot of fat as well as a lot of cholesterol, were banned from many tables, and Egg Beaters were used to make egg white omelets and other low-fat egg dishes.

Then the tide turned, and we were told one or two eggs a week, or even one a day (gasp), were OK unless we were diabetic, in which case we should stick to those tasteless egg white omelets. But then the experts changed their minds again and said eggs were OK even for people with diabetes.

And Harvard's Walter Willet said, “There was never any data that showed that people who ate more eggs had higher risk of heart attacks.”

Now comes a study from Finland that says that egg metabolites in blood are related to a lower risk of type 2 diabetes. Note that risk factors in the blood are not the same as actual mortality rates in egg eaters. But they're consistent with the idea that eggs aren't poison, and a previous study had linked egg eating with a lower risk of type 2. This new study was designed to help figure out how the egg consumption affected diabetes risk.

Have we yo-yo'd back to the 1950s and 1960s in terms of egg advice? I suspect we have.