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Would eating medium chain TGs actually inhibit to a certain degree your body's ability to burn fat it has stored? Or would it speed this up a bit?
I'm thinking, if your diet contains these fats that are more quickly oxidized, will your body use these up first (not taking into account carb oxidation), then call on fat stores for energy?
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It would speed it up for sure. As stated in the original post, one of the destinations of fats are to be stored themselves when digested. Having MCT’s decreases this probability, shifting the metabolism of fats towards its anabolic functions such as increasing diet induced thermogenesis and perhaps the production of anabolic hormones!
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I would be interested to see an article that talks about the mechanism fat stores in the body are broken down for energy. At what point do they get tapped into?
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There are two factors to consider here: nutrient partitioning and total calories metabolized.
Nutrient Partitioning can be defined as the distribution of ingested nutrients among basal metabolism, growth, tissue maintenance and repair, physical activity, and other forms of energy expenditure and nutrient storage. The goal is to partition nutrients away from fat storage, and towards other vital functions such as replenishment of glycogen stores (which is the storage form of glucose, and the predominant source of energy used during high intensity exercise, such as weight lifting).
One of the most effective ways to do this is manipulation of the hormone insulin. Insulin is a hormone released from the beta cells in the islets of Langerhans of the pancreas. Its primary secretagogue (anything that stimulates the release of a hormone) is glucose. A primary importance of carbs is therefore, to manipulate this hormone.
Insulin has numerous anabolic effects such as increasing protein synthesis and glycogen replenishment. However, insulin also spares fat from being utilized as fuel, and chronic production of this hormone can increase de-nova lypogenic enzymes, increasing the probability of converting carbohydrates to fat for storage. Thus, it is important to use various methods to enhance insulin sensitivity.
What is important to understand is that chronic release of a hormone will promote down regulation. Receptors exposed to hormones to unphysiologically high concentrations, or for long periods of time, are down regulated (become less available for hormone action). Thus, by constantly having high Gi carbs for instance, insulin will be constantly released, causing down regulation.
One of the best ways to enhance insulin sensitivity is through exercise. Omega 3 fatty acids have also been shown to enhance insulin sensitivity, as well as dietary fiber.
Knowing the actions of insulin, this is why some people opt for carb cycling when they diet.
And there are numerous other ways you can manipulate your diet so that you minimize fat storage of ingested nutrients, such as having MCT’s.
Exercise is one of the most effective ways to manipulate this. Here is a quote from the current issue of JHR from Wilson (2005) The Growth Hormone – IGF Axis and its Role in Muscular Hypertrophy
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In summary, during catabolic states, when muscles are taxed the body adapts by lowering IGF-1 levels, while local IGF-1 levels in the trained musculature increase. This creates systemic catabolism, while maintaining the possibility for local anabolism. Theintz (1993) suggests that this attenuates somatic growth while maintaining muscular adaptation during states of caloric restriction. These hormonal adaptations have been seen in both female gymnasts and wrestlers who enter states of catabolism during weight loss periods, while still maintaining or adding musculature in the trained regions (Jahreis et al., 1991, Roemmich and Sinning, 1997, Elokim et al., 2005). Finally, it also explains partially why periods of overfeeding facilitate a more whole body anabolic environment conducive to size increases.
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Therefore, by manipulating nutrient partitioning techniques, you can add muscle, and lose fat at the same time! The competitors of the HYPERplasia challenge are living proof of this.
Next, you obviously will need to metabolize calories. There are 3 primary avenues for this: Diet Induced Thermogenesis (DIT), Basal Metabolic Rate (BMR), and Exercise.
The president and I plan on writing an extensive article on DIT for the upcoming issue of JHR. But typically, this accounts for 10% of the calories you metabolize. DIT is the increase in the amount of calories metabolized caused by eating foods. This is entirely dependent on the type of foods you eat.
BMR is the basic energy requirements needed to maintain vital organs such as the liver and kidney, as well as muscles, which can obviously be manipulated and will greatly increase your BMR. Typically, this accounts for 65% of daily oxidative metabolism. So it is absolutely vital to maintain it. Dieting tends to decreases it, so this is why people utilize various methods such as carb cycling and calorie cycling.
The last one is exercise, and the amount of calories you metabolize through this avenue can obviously vary.
If you want to optimize the amount of calories you metabolize from fat during exercise, evidence suggests training at 65% of your VO2 max will metabolize the highest total amount of fat. For more information on this, read these articles by Wilson and Wilson (2005):
Fast Acting Hormones and their Role in Fuel use during Exercise
Slow Acting Hormones and their Role in Fuel use during Exercise
Analysis of Nutrient use during Low, Moderate, and High Intensity Exercise
Direct Comparisons of Fuel use during Low, Moderate, and High Intensity Exercises