There is no one diet that is best for everyone but depending on what you want from your food, or diet, understanding the differences are important. The main difference between these two types of low carbohydrate diets are the ratios. It is very important to note that neither are high protein diets. If you consume more protein than your body utilizes it will be converted to glucose.
The brain uses two fuel sources glucose-produced from carbs and ketones produced from fats. Our early ancestors, hunters and gatherers, naturally used fats as their fuel because this was before farming and agricultural by-products. They would have to fast when they ran out of food and hunt for more fuel. This is so different than our current day utilization of food. We are able to buy whatever we want whenever we want it. Usually, in our current day society, the fuel source is glucose. As we have seen in these past few decades with the rise of diabetes, obesity, and many other modern-day illnesses I believe there is a direct correlation.
Keto diet, “long chain triglyceride diet” uses a measured ratio of 5-10% carbs, 20-25% protein, and a 70-80% fat intake. Or, another way to look at is a ratio of 4:1 or 3:1 fat to protein. The extreme low carb intake forces the body to go into a “ketogenic” state and burn fat as the main fuel source instead of carbohydrates. I remember this from the “Dr. Atkins” diet many many years ago. Why is this good? Well, it is good for rapid weight loss and neurological disorders. Carbs in short lead to excess water storage. The fluid is in the extracellular tissue, not being utilized by the cells themselves. But more importantly, it is extremely beneficial for neurological disorders specifically epilepsy. It has also been shown to dramatically help diabetics as well and folks with ADHD.
The breakdown of ketones has many positive side benefits such as fat burning, mental clarity and cognition, increased physical energy, fewer cravings, and steady blood sugar. The brain is made of 60% fat. It is a very hungry organ and needs to be fed.
Paleo also has a low carb profile, however, the ratios are not as chemically important to create a state of ketosis. You are eating more protein but are also eating plants and wild berries. The fruits are more representative of the original sized fruit before they have become mega-sized and bred for sweetness. Paleo is a philosophy of eating the way our ancestors ate before modern civilization started changing the chemical state of our food. This is from whole natural food to the current world of processed foods. The Paleo thought is that if you remove those foods then you remove the diseases that go along with them. Paleo also includes removing refined carbohydrates, table salt, and pretty much anything man-made that we would not have had access to in early human days. This is because it’s theorized the majority of our modern diseases have come from our abundant consumption of these man-made elements.