Ketosis Part II: Regulation

Now that we have a good idea of what ketone bodies are, and how they start to get formed and where I think it is time to loot at the regulation of the process.  I think what has been really interesting to me in researching this topic is that I expected to find some sort of “master switch” for ketosis.  What I mean by that is I figured that something would happen that would turn on ketosis, and as such you are either in ketosis or out of ketosis.  However, as we saw in the last article everyone produces small amounts of ketones at rest, and ketosis is physiologic process that just happens when the substrates are available and are not being used for other processes. 

There are two main types of regulators for ketogenesis, and while they may seem very different to some people, I think they are rather similar.  It all depends on what energy our body is using, and in what amounts.  Ketogenesis can be controlled either through physiologic processes or through enzymatic processes.  We will start with the physiologic ways that ketosis is controlled, and then go to the enzymatic/hormonal ways, since those are probably a bit more complicated.

When we talk about physiologic processes that induce ketosis we are talking about what is going on in our body to make it start naturally producing ketone bodies.  There are three main ways this happens, and a fourth little trick people use to jump start the process (any guesses now what that is?).  The three ways are: starvation/fasting, prolonged exercise, and a low carb/high fat diet.  Let’s take a look at each of these in turn.

Benefits of Intermittent Fasting

We are going to take a quick break from our regularly scheduled programming because I just stumbled upon this new study from FASEB. The study is titled "Timed high-fat diet resets circadian metabolism and prevents obesity".  The wording "Timed high-fat diets"  is kind of confusing, but if you read the paper what they did was an intermittent fasting protocol.  Rats were separated into one of 4 different groups: an ad libitum low-fat diet (AL-LF), an ad libitum high-fat diet (AL-HF), a restricted feeding low-fat diet (RF-LF), or finally a restricted feeding high-fat diet (RF-HF).  The restricted feeding group was only allowed to eat for 4 hours/day, while the ad lib groups could eat whenever they want.

The results were pretty striking.  The RF-HF mice consumed the same amount of calories as the AL-LF mice, but had a 12% reduction in body weight compared to them.  Also, the RF-HF mice also had lower cholesterol levels, higher insulin sensitivity, and lower inflammatory markers than all the other study groups.  The RF-HF mice also showed signs of improved lipid oxidation, showing that the fat they consumed ended up being burned for energy, and not stored.  Not to mention that the HF diet was based on soybean oil and these are mice that are predisposed to become obese on a high-fat diet.  Finally you might think that these researchers were starving these mice on the RF protocols, but the RF-HF mice had lower ghrelin, indicating a higher degree of satiety.

A lot of people think that the benefits of intermittent fasting come from reducing calorie intake due to the small eating window.  However, this study shows that even if you eat the same amount of food, and pretty crappy food at that, eating in an IF way can help you improve your health.  I have found that I naturally tend to eat in a restricted feeding type way, with most of my eating happening a 6 to 8 hour window just naturally.  I just thought this was a pretty interesting study and showed some of the very powerful benefits of IF protocols for health.