The basics

What is Keto?

Keto is short for ketogenic diet. A ketogenic diet is a very low carbohydrate diet, higher in fat with a moderate amount of protein.
It takes the names from ketosis, the metabolic state when ketones, small molecules produced by the liver when fat is broken down for fuel, are above a certain level.

The answer to the question of what is ketosis and ketone bodies can be quite geeky and complex. Dr. Peter Attia explains it better than I do in his own blog post Ketosis - advantaged or misunderstood state?

The main idea is to force your body to enter nutricional ketosis. A sustainable metabolic state in where body makes use of your fat for fuel in a natural and easy way. For this you will have to restrict carbohydrates below a certain level.

The term nutricional ketosis was coined by Jeff Volek PhD RD and Dr. Stephen Phinney MD PhD in their book The Art and Science of Low Carbohydrate Living.
Dr. Volek and Dr. Phinney's research, together with many recent studies, have given the basics for a well formulated and sustainable ketogenic diet. And that was the model I followed to get back to my ideal weight.

How does Keto help me lose weight?

I am going ahead and say that Keto is not just for weight loss. Keto is nothing more of a modern term for how we used to eat for generations before western societies decide it was best to increase sugar and reduce fat in order to stay healthy. Actually the opposite happened. More got fat, type 2 diabetes mellitus and other modern diseases increased exponentially despite us following the guidelines that should have helped prevent it. 

It is increasingly believed that obesity, and diseases that accompany weight gain are linked to hormone imbalance or resistance. By reducing the amount of carbohydrates, we will be reducing the amount of insulin required, allowing our body to make use of fatty acids and ketone bodies for fuel by braking up the fat reserves.

The main driver for Keto works by controlling insulin. As a result, this will allow your body to use your fat stores. We basically gain control of the mechanism that tells the body when and how to use the fat we have been storing for decades. 

In simple terms, Insulin is an hormone produced in the pancreas which, among other functions, has the job to signal cells to make use of the glucose present in the blood stream. At same time it will tell the body to increase fat storage.

The majority of the diets work under the principle that we need to use more calories than we take in. It is all about the calories, we have been told.
But the notion of calories in and calories out is a ridiculous over-simplification that doesn't actually work for the majority of the people. If it did, obesity wouldn't be on the rise, because we are all being told to move more and eat less. Gyms are as full as shelves are with low fat products.

Dr. Jason Fung explains in it his 'The Aetiology of Obesity' video series that we have been gaining weight despite following the approved and common agreed healthy guidelines. According to Dr. Fung, and many others, instead of eating less, more often, low fat food and whole grains we should actually be eating less often, less grains and high fats.
For the majority of the people, no matter how many diets they try, how many times they exercise, how often they count calories or follow the standard guidelines, the weight always keeps coming back. In fact recent studies show that obesity, diabetes, cardiovascular diseases, cancer and many other modern diseases have been raising despite many of the vilified foods seeing a reduction in consumption.

Prof. Tim Noakes, for years an avid advocate of carbohydrate use for performance, claims that we have got it all wrong. If fact he apologised for it, as medical doctor, professor and scientist.
We should go back to eat how our bodies have evolved to.

We have been around for far longer than the current standard guidelines. Even agriculture is a recent discovery when compared to how long humans have been around for. The Fat Head Movie (this is just a clip) puts it quite clearly. Film maker Tom Naughton explains it in a very funny way.

It all comes down to this:
Right now we are told to eat 45% of our diet as grains and reduce fat.
But if we consume far too much carbohydrates, worse, we eat the wrong ones and far too often, we may develop insulin resistance or metabolic syndrome as a result. And even if we haven't, just know that as far as the body is concerned carbohydrates are sugars.

Our body can use glucose or ketones and fatty acids for energy. But in the presence of both, glucose takes precedent. There's several reasons or theories for it. One of the reasons is because there's limit storage space for glucose. The body keeps roughly 24h worth of energy in glucose form as glycogen, located in the liver and muscles. In contrast, fat is stored everywhere else.
Glucose is a fast burning fuel and the body keeps it for when a boost of energy is required. From an evolutionary point of view, this would have been useful in case you have to run away from a predator. But in other circumstances it should be able to use both and store both as fat to be used later when food is scarce.
You can actually live with no food if you have enough fat reserves. The longest fast recorded was 382 days. Yes, more than Jesus.  Anyway... moving on.

The body has to maintain a small amount of glucose for certain functions but too much of will cause other health problems. In order to regulate this fine balance the pancreas releases insulin into the bloodstream to direct  glucose to the cells that are in need of energy while at the same time block them from using fatty acids. 
The whole time insulin is up, doing what its supposed to do, the body is in fact in fat storage mode. And, the more resistant your cells are to insulin, the more insulin the body will need pump into the bloodstream in order to perform the same operation.
Fructose, another type of sugar, found in fruit, cannot be metabolized by the liver so it is turned into fat for storage straight way.
This deserves its own chapter but I feel the way food manufacturers and marketing companies use and sell this sugar is borderline illegal. That Sugar Film shows the impact of eating sugars at the recommended dosage.

In short, control insulin and you control the world. I mean your world.
That is about it. There will be other chances to go deeper into the science.

If you clicked any of the links above you would have probably have learned that humans are meant to go in and out of ketosis every day. A good example is when we sleep, the body naturally moves into a fasting state. And at some point would break the fast with whatever food was caught.

It's worth noting that metabolic syndrome has also been linked not only to obesity but to diabetes, many types of cancer, Alzheimer's (also called type 3 diabetes), and many others.

If you're interested in more of the science behind all this I highly encourage you to watch one of Jeff Volek's talks in Keto Adaptation.

In fact here's my Keto playlist on YouTube. Keep calm and Keto on.