More Reasons to Eat Low Carb

Several recent studies have supported the consumption of low-carbohydrate diets, especially, of course for people with diabetes but also for people without the disease.

The first study showed that although artificial sweeteners by themselves don't affect metabolism or the brain's sensing of a sweet taste, when these sweeteners are eaten along with carbs, they do, causing insulin resistance and a decrease in the brain's response to a sweet taste. These changes increase the risk of obesity.

In other words, it's OK to drink a diet soda with some steak, but not with french fries.

The mechanism of this effect is not clear, but it could explain seemingly contradictory results of studies of artificial sweeteners. Some studies may have given the sweeteners along with carbs, say adding them to yogurt, whereas others did not.

The full text of the study is available. I found it a bit confusing. For example, they say, ". . . in healthy human adults we observed reduced insulin sensitivity and blunted brain response to sucrose following consumption of seven 355 mL beverages over 2 weeks," but they don't say what the beverages contained.

Nevertheless, the overall conclusions are interesting: "consuming sucralose with, but not without, a carbohydrate rapidly impairs glucose metabolism." Of course, if you're on a low-carb diet, you're less apt to be using a sweetener with significant amounts of carbohydrate.

Another study suggests that low-carb diets may help prevent age-related changes in the brain. The authors say that communication between brain regions destabilizes with age, starting in the late 40s, and destabilization correlates with poorer cognition and accelerates with insulin resistance.

The researchers found that glucose decreases, and ketones (which are formed when glucose ingestion is low) increase, the stability of brain networks. 

The authors say that as people get older, "their brains start to lose the ability to metabolize glucose efficiently, causing neurons to slowly starve, and brain networks to destabilize." Hence a ketone-producing low-carb diet could provide the energy the brains need.

They used functional MRI to image the brains of 1000 people aged 18 to 88 and found that destabilization was associated with impaired cognition and was accelerated with type 2 diabetes, which affects the neurons' ability to metabolize glucose. They found that either a low-carb diet or a ketone-rich drink stabilized the networks.

The last study found that mice fed a ketogenic diet were better able to fight off the influenza virus than mice on high-carbohydrate diet. The authors said that the diet enhances the production of a certain type of T cell that produces mucus in the lungs that helps to trap the virus.

This study was done with the flu virus, and there is no evidence that a ketogenic diet would protect against coronavirus. But perhaps it could. We know that high blood glucose levels weaken your immune system, and people on low-carb diets tend to have lower glucose levels, so it could help in that way as well as possibly triggering lung changes.

Not everyone is happy on a low-carb diet long term, but it's certainly worth trying.