Is the Ketogenic Diet Just Another Low-Carb Diet?

Is the Ketogenic Diet Just Another Low-Carb Diet?

 

Unfortunately, the definition of a low-carbohydrate diet is confounded by the fact that there is no minimum recommended daily allowance for carbohydrates. However, a commonly accepted definition is that a low-carb diet is one that supplies less than 50 percent of its calories from carbohydrates (Feinman et al., 2003). This is in stark contrast to the less-than-50-grams-per-day recommendation for very-low-carbohydrate ketogenic diets. (If the friend we mentioned earlier in the chapter who was eating around 4,500 calories per day used the 50 percent definition, he’d be “low-carb” if he ate 550 grams of carbs a day! We all know that this is anything but low-carb.)

As previously discussed, a ketogenic diet is one in which glucogenic substrates are low enough to force the body to transition from metabolizing glucose to burning fat and subsequently producing ketones. So while a ketogenic diet is low in carbohydrates, a low-carb diet isn’t necessarily ketogenic.

A classic study (Young et al., 1971) demonstrated a clear difference between low-carb and ketogenic diets. Scientists took overweight young men and placed them on “low-carbohydrate” diets consisting of 30, 60, or 100 grams of carbohydrates per day. They found that after nine weeks, the 100-gram group was not in ketosis at all, while the 30-gram group had achieved high levels of ketosis.Moreover, the 30-gram group lost more fat than both the 60-gram group and the 100-gram group despite there being no differences in total calories or protein consumed. This study clearly demonstrates that not all low-carbohydrate diets are the same, and certainly not all are ketogenic. 

KETOSIS : The Basics

KETOSIS : The Basics

what it means to be in a state of ketosis.

For our entire lives, we’ve been told that the primary source of energy for our bodies is carbohydrates, or glucose. However, there is an alternative fuel source that our bodies can use under various conditions—a fuel source that is more efficient and often underutilized. That source is ketones.

Ketone bodies are produced when the body metabolizes, or breaks down, fat. The cells in the body are able to utilize these ketones as fuel to help power everyday functions. There are three kinds of ketone bodies:

• acetoacetate (AcAc)

• beta-hydroxybutyrate (BHB)

• acetone (Acetone is actually produced by breaking down acetoacetate, making it more of a by-product, but for our purposes, it can be considered a ketone body.)

Each type of ketone body serves unique functions and can be tested for. For example, BHB in the blood can be tested using a finger prick, AcAc in the urine can be measured using a urine strip, and acetone in the breath can be measured using a breath meter.

All of us, at some point in our lives and routinely throughout the day, have some amount of ketones in our blood, yet we often don’t realize it. For example, if you ate dinner at 5 p.m. and didn’t eat again until 10 a.m. the next day, you likely would be in a minor state of ketosis since you hadn’t eaten food and had been fasting for seventeen hours. Our bodies naturally make ketones under these circumstances; however, most people never achieve a consistent state of ketosis due to the constant supply of carbohydrates in their diet. Therefore, instead of breaking down and metabolizing fat, our bodies metabolize carbohydrates—or, rather, glucose. In other words, when glucose is available in the blood, the body will use that to make energy instead of dietary fat or stored body fat. However, when glucose isn’t as readily available (glucose is still around but isn’t as high), the body turns to breaking down fat, and ketones become its primary fuel source.

Ketos is is, essentially, the state of having elevated ketone levels, typically above 0.5 millimole per liter, or mmol/L. How a state of ketosis is induced, how high a person’s blood ketones are, and what benefits are achieved from that degree of ketosis vary widely from individual to individual.