The theory behind the high-fat diet is to use dietary fat as fuel in place of carbohydrate, thereby lowering the rate of insulin in the blood. Since insulin stimulates fat storage and blocks fat breakdown, this would seem to be a great solution. Unfortunately, supplying energy in the form of long chain fats doesnít work. But, it has been shown that supplying energy as medium chain triglycerides, like CapTri®, does work in reducing the bad effects of insulin. You can supply up to 30% of your calories from MCT while limiting conventional fat to 5% of your calories. You can then make up the rest of your calories (not including the protein, which is the first thing you should account for when planning your diet) with complex carbohydrates, avoiding simple sugars and refined carbohydrates. There are several differences between this diet, utilizing MCT, and the high-fat (long chain triglyceride) diet. First, regular fat has a tendency to store as body fat very easily, while excess calories from MCTs are released as heat in a process called thermogenesis. This allows bodybuilders and other athletes to substitute fat calories for carbs to keep insulin levels low and still avoid the pitfalls of a high-fat, low-carb diet. Whereas the high fat diets will limit carbs to 5-20% so you can put your body into ketosis, you can maintain insulin at low levels and shift your body into a fat-burning mode while still consuming 40-60% of your calories from carbs. This works because combining protein, fibrous carbs and MCT slows the release of carbs into the bloodstream, resulting in a much lower insulin level. And from previous articles, it is known that weight training is an anaerobic (without oxygen) activity and the only energy source that can be used anaerobically is carbohydrate. There are other benefits of a high-carb, MCT diet. It is well-known that caloric-restrictive diets donít work. the metabolism slows and nearly half of the weight lost is in the form of lean mass. And as you lose more and more muscle, your burn fewer and fewer calories. But carbohydrate food increases the metabolic rate more than fat, and is converted to ATP with less efficiency than fat, meaning more is lost as heat, and in the process, not available to be stored as fat.

Debate has gone on as to what’s the best dietary fuel for bodybuilders. There are two schools of thought. The first is the diet which uses carbs for energy. The second is the high-fat diet in which most of the day’s calories are derived from fat. The rationale here is that by keeping carbs to a minimum, you also keep insulin levels as low as possible, thereby promoting the use of stored body fat for energy. Both diets have one thing in common: high protein intake. Studies have documented that bodybuilders and endurance athletes need extra protein in their diet to make up for the loss of amino acids which are oxidized as fuel during exercise and to repair muscle tissue which is damaged during training. To promote the use of stored body fat for energy, one key requirement must be met. The body must be put into an energy deficit. That means you must expend more energy than you consume. The best way I’ve found to achieve energy deficit without losing muscle mass is to increase exercise, particularly aerobic activity, instead of cutting calories. This method keeps the metabolism increased so more fat can be burned even after exercise, while sparing, and possibly even increasing, muscle mass. So protein and calories are kept at elevated levels, what about the primary energy source? Fat or carbs? The Parrillo Program is based on supplying the bulk of dietary energy from complex carbs while keeping dietary fat to a minimum. There are three basic reasons for this. First is personal experience. The vast majority of bodybuilders I’ve worked and talked with use the high-carb approach because it works the best. And what matters most in the professional and national amateur ranks is results. If the high-fat diet worked best, everyone would be doing it. The second reason for the low-fat approach is for general health reasons. Heart disease is the number one killer of people in this country. And the root cause of this problem is the excess fat (and cholesterol) in the diet. A diet high in conventional dietary fat also has been associated with some cancers, including breast and colon cancer. Finally, research has shown carbohydrate fuel as the preferred energy source for athletes. Weight lifting is an anaerobic activity, meaning energy is produced without oxygen. Carbohydrate is the body’s preferred fuel substrate that can broken down to yield energy without reacting with oxygen. Fat, however, requires oxygen to be burned for energy, thereby making it very inefficient for intense activity such as weight lifting which requires a quick and powerful burst of energy. Nutrients and oxygen cannot be supplied to the muscles fat enough to supply the muscle with energy from fat, it must come through either the glycolysis pathway or the phosphagen pathway. Therefore, fat is not a good source of energy for bodybuilding. Fat can burned, however, for medium to low intensity activities like walking, or riding the stationary bike are not oxygen-limiting. This is why the Parrillo Performance Program recommends aerobics as part of the training program. It is the best way to get rid of excess body fat. The question then is, if you’re trying to get rid of body fat, why be eating more fat? That’s just more energy that has to be burned through aerobics. While carbs have the ability to be burned immediately, stored as glycogen or converted to fat, dietary fat does two things. It can be burned for energy or stored as body fat. It cannot be converted to carbohydrate fuel. So any fat consumed must be burned for energy or stored as adipose. Using carbs as the preferred energy substrate has other advantages. First, excess carbs are first used to replenish glycogen stores in the muscles and the liver. When there are still excess carbs, they can be converted to fat in the body, but this process is very inefficient. Studies have shown that about 25% of the energy in a carbohydrate molecule is spent in the process of digestion, assimilation, transport and conversion to fat. This compares to only a 3% loss in energy for a fat molecule to be stored as adipose.