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From: bchm17@unlclass1.unl.edu (bchm17)
Subject: High Fat Diet

I thought I would explain this particular version of the high fat diet because it is quite different from the Atkins diet or any of the other diets like it that I have seen.
ATP (adenosine triphosphate) is the source of all metabolic activity in the human body. In order to get the energy the body needs for muscle contraction, breathing, brain cell function and virtually all other activities, ATP must be generated. People have gotten the idea that you must have glycogen and glucose that comes from carbohydrates for the body to produce and replenish ATP and survive.
What people don't understand is that protein and fat have their own mechanism for providing energy to the body and replenishing ATP. It's a misconception that you need carbs to function.
When carbs make up the bulk of your diet, you basically burn the glucose from the carbs as energy. Glucose enters the body, and insulin is secreted by the pancreas to utilize it for immediate energy, or store it as glycogen in the liver and muscles. The gluocse not stored as glycogen is made into triglycerides (bodyfat). When needed for energy, the stored glycogen is converted back to glucose and used up directly by a cell or transported through the bloodstream to other cells for conversion and use as energy.
When fat makes up the bulk of your diet, you don't have those large amounts of glycogen or glucose available for energy anymore. Most of your energy will come from the breakdown of free fatty acids from your diet or from the fat stored on your body. Instead of burning the stored glycogen or glucose for energy, the body burns free fatty acids or triglycerides (the storage form of the free fatty acids).
Basically, a diet high in fat activates the lipolytic (fat burning) enzymes in your body and decreases the acitivity of the lipogenic (fat producing) enzymes. Dietary free fatty acids and triglycerides become the body's main energy source. The triglycerides are broken down to free fatty acids and then ketones, a source that can be used for energy by body cells. The free fatty acids take the place of glucose, and the triglycerides act like glycogen.
When carbs are the main form of energy to the body, the body produces insulin to process it and store it. This is all well and good but, as we discussed above, one of the problems with insulin is that activates the lipogenic (fat producing) enzymes on the body and decreases the activity of the lipolytic (fat burning) enzymes. What this leads to is an increased storing of body fat and a decrease in the amount of stored fat that will be burned.
The exact opposite occurs on the high fat diet. After undergoing the "metabolic shift" from being a carb-burning machine to a fat burner, lipogenesis (the production and laying down of fat on the body) decreases, and lipolysis (the burning of both dietary and bodyfat for energy) increases. You're burning fat as your primary fuel, and instead of using glycogen or breaking down precious protein, you'll burn off the fat on your body for energy as needed.
This can have a big effect on overall bodyfat, and research has now begun to document this effect. In one study of ideal-weight human subjects, it was found that high fat diets were accompanied by a very strong lipolytic (fat burning) effect.(ref 1)
Kather H, Wieland E, Scheurer A, et al. Influences of variation in total energy intake and dietary consumption on regulation of fat cell lipolysis in ideal weight subjects. J Clin Invest 1987; 80(2): 556-72.
In another study focusing on obese subjects, it was found that, when offered high carb/relatively low fat diets or low carb/relatively high fat diets, the subjects on the lower carb diet lost significantly more fat. (ref 2)
Rabast U,Kasper H, Schonborn J. Comparative studies in obese subjects fed carbohydrate-restricted and high carbohydrate diets. Nutr Metab 1978; 22(5): 269-77.
It may sound crazy, but that's the way the body works. Once you've adapted to a high fat diet, fat does not beget fat. Despite what you have been told, a high fat diet does not put fat on. It takes it off.
Studies with other animals have produced additional eye-popping results. One study of hamsters found that a high fat diet added weight while decreasing lipogenesis (fat build up). The hamsters gained large amounts of weight, but this weight was more from an increase in lean body mass than fat.(ref 3)
Sandretto AM, Tsai AC. Effects of fat intake on body composition and hepatic lipogenic enzyme activities of hamsters shortly after exercise cessation. Amer J Clin Nutr 1988; 47(2):175-9.
In another study it was found that hamsters fed a high fat diet had lower lipogenic (fat producing) enzyme activity and less body fat content than low-fat-fed hamsters under both sedentary and exercise conditions.(ref 4)
Tsai AC, Gong TW. MOdulation of the exercise and retirement effetcs by dietary fat intake in hamsters. J Nutr 1987; 117(6): 1149-53.
One important by-product of the "metabolic shift" that takes place when you move from a high carb diet to the high fat diet is that fat becomes a protector of protein in the body. When you're utilizing carbs as your main source of energy, the body will take muscle protein, break it down and form glucose (gluconeogenesis) from it to burn for energy, once immediate energy stores are exhuasted. This is where catabolic activity (muscle breakdown) takes place. You'll be sitting there, happily working, and you're actually making your muscle shrink away as you do it. You're basically burning muscle to fuel your workout.
You won't get nearly this amount of muscle breakdown on the high fat diet. Some muscle will be burned, but available fat will serve as an alternative to muscle as an energy source to a large degree.
Anytime you're exercising and the body needs energy, it will break down what it needs, including muscle, to supply that energy. One of the ways bodybuilders fight this is to sip glucose drinks during a workout. The body won't need to break down muscle as much for energy because it has an outside source of energy constantly coming in. Fat works in the same way when you're on the high fat diet. It protects the muscle by serving as an alternative, more available source of energy.
It must be remembered that, along with anabolism (the buildup of muscle tissue), the bodybuilder is also very concerned with catabolism ( the breakdown of this tissue). Research shows that the anabolic diet could well also be called the anti-catabolic diet. Along with enabling the body's hormonal system to better burn fat and produce lean body mass, it also aids in decreasing the amount of muscle that could be lost during a workout or over the course of a diet phase.
Research has shown that the ketone bodies burned for energy in the anabolic diet, D-beta-hydroxybuterate and acetoacetate, actually decrease protein catabolism. (ref 1)
Giorski J. Muscle triglyceride metabolism during exercise. Can J Phys Pharm 1992; 70(1):123-31.
A recent study with laboratory rats also showed that a combined treatment of insulin, testosterone and a high fat/high protein diet led to decreased loss of muscle protein and growth caused by the catabolic hormone corticosterone. (ref 2)
Ohtsuka A, Hayashi K, Noda T, et al. Reduction of corticosterone-induced muscle proteolysis and growth retardation by a combined treatment with insulin, testosterone and high protein-high fat diet in rats.
Another study showed higher protein gains and lower fat gains for rats on a high fat diet. (ref 3 )
McCarger LJ, Baracos VE, and Clandinin MT. Influence of dietary carbohydrate-to-fat ratio on whole body nitrogen retention and body composition in adult rats. J Nutr 1989; 119(9):1240-5.
The implications for similarly decreased catabolism in humans through adopting the high fat diet are obvious.
Many people suspect that they'll experience a loss of energy on the anabolic diet because the body isn't getting glucose from carbs anymore but, again this just isn't true. The free fatty acids, triglycerides and ketones your body burns provides more than enough energy to get through a workout. Red Meat is also high in cretin, which is one of the compounds that increases high energy phosphates in the blood and the availability of ATP. There's no lack of energy.
Though the anabolic diet contains a carb loading component, is isn't of the duration necessary to return the body to a glucose burning metabolism. Like insulin, carbohydrates are controlled and manipulated in the anabolic diet to maximize growth benefits and minimize their drawbacks.

Jeffrey P. Krabbe
Pre-Dietetics, Senior
University of Nebraska, Lincoln

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