At this point we have read about the major kinds of macronutrients, the 2 forms of metabolic process that your body can operate on, and exactly why these are necessary points to consider for survival. In terms of suggestions the scales are leaning quite heavily toward a fat based diet instead of one dependent on carbohydrates such as grains, flour as well as sugar.

To this point, we have been concentrating mainly on the effects of carbohydrates on blood insulin in your body. Now, we are going to check out a vital hormone that has just entered the limelight in nutritional science: leptin.

What's important about fat mice?

In 1950, scientists were in the process of breeding lab rats for different features. One of the variations was a tremendously hungry mouse that would eat until it was physically unable to. All these mice would eventually become obese, giving them the appropriate nickname of 'obese mice'.

It was 4 decades before the problem of why the obese mice could eat so much was solved. At Rockefeller University in 1994, a researcher known as Jeffrey Friedman was able to segregate a protein which, when injected to the obese mice, would enable them to eat normally and get back to normal weight. This protein was a mix of 167 amino acids called leptin.

The way that the hormone functions is by curbing the body's hunger. When you feel hungry, you will continue to eat until you are 'satisfied', however the amount of food which will allow you to be contented is determined by leptin. The reason obese mice ate the way they did was as they were genetically not able to possibly produce the hormone or did not have functioning leptin receptors. Because of this, they continued eating to satisfy their hunger. This seems like an awesome science story but the applications to survival foods are enormous.

Messing up the hormone

In nature, the hormone is the perfect feedback loop to sustaining a normal body weight. It is made by fat cells themselves, therefore theoretically, having more fat cells would make a person feel much less hungry. Fat levels will decrease to normal and nobody would be at a bad weight. But there are actually hundreds of millions of human examples to verify that it isn't the case these days.

The main reason this occurs is leptin insensitivity. From having persistently elevated levels of the hormone, receptors in the brain can't tell when leptin levels are low or high. In essence, this is exactly what happened with the obese rats - with no capability to tell when they are satisfied they would eat till they couldn't eat any more. This would be disastrous in a survival situation, either leading to unnecessarily high food intake or being extremely stressful mentally from continuous hunger.

Luckily, there is a remedy for this. Low carb diets have shown to restore leptin sensitivity in two methods. First, they reduce blood triglycerides which makes it a lot easier for the hormone to reach the brain. Second, they have the outcome of lowering bodyfat that plays a role in chronically increased levels. Additionally, many carbohydates like fructose and wheat have been shown to adversely affect receptors.

You decrease carbs, you lessen leptin insensitivity, you decrease hunger.