The Order of Energy Utilization Back to our table of stored energy in an average 70 kg man. Organ ************** Available energy (kcal)
************ glucose/glycogen ***** fat ****** protein
blood *********** 60 ************** 45 ******* 0
liver *********** 400 ************* 450 ****** 400
brain *********** 8 *************** 0 ******** 0
muscle ********** 1200 ************ 450 ****** 24000
adipose(fat) **** 80 ************** 135,000 ** 40 from Stryer Biochemistry 4th Edition page 771 Glucose and Glycogen 1600 kcal of available energy As you can see from the table above, there are three categories of energy. Glucose and glycogen (a polymer of glucose) is the first category and the most readily available. This is the energy that most of us utilize most of the day. The human body needs plentiful supplies of glucose, especially since it is basically the only molecule that the brain can metabolize. Good sources of real complex unprocessed carbohydrates are grains, potatoes and rice. Protein 24000+ kcal The human body can process protein to make glucose via a pathway called gluconeogenesis. During periods of starvation the protein / lean body mass of the body can be catabolized to provide glucose for the brain. This is not a good way however, to lose weight as you are losing what you don't want to lose -lean body mass. As you can see from the chart most of the protein available for energy utilization comes from muscle. Fat 135,000 kcal available stored energy By far the most stored energy the human has is in fat. However, it is also the last energy source the body will turn to unless the requisite enzyme systems are already in place to process the fat. One of the advantages of the fat burning system is that you don't have to be starving to have it supply glucose for your brain or your muscles. You do, however, have to have trained your metabolism sufficiently so that when you call on this "fat burning" system, it will be able to proceed at a rate fast enough (have enough enzymes present) to supply enough glucose to be significant. Running and learning to burn fat Long distance running has long been an area of "fat burning." As mentioned previously, most humans can store about 20 miles of energy from glycogen / glucose sources. After about twenty miles most humans will switch to fat burning. What has to be understood here is that the rate of your fat burning will be dependent on how much you trained in a glucagon / fat burning / energy utilization state. Even if you have trained a lot this way you may still slow down when you switch but the slow down will not be as severe as if you have not trained your metabolism at all. If you haven't trained your metabolism at all, you will probably be walking the last six miles. How to learn to burn fat ... In order for your body to be able to burn fat, you have to enter a glucagon state -period. There is no other way. You cannot be eating six, seven or eight meals a day. If fact, it is very hard to learn to burn fat if the first thing you do every day is eat a big breakfast. You wake up ready to go glucagon for a while and the first thing you do is ... eat breakfast. Up goes your insulin, down goes your glucagon. Your stomach empties in usually about thirty minutes and then you are hungry again. You wait till about ten in the morning have a snack and just about the time your insulin levels are starting to come down -up they go again. The cycle repeats itself all day. Timing and hunger ... The stomach usually empties in thirty minutes. Usually it takes two to three hours for the blood sugar to return to normal and the insulin levels to begin to return to fasting levels. This is one of the real problems with the human body. The biochemistry of energy metabolism is at least 100,000 years old with power of hunger -also 100,000 years old. However, 100,000 years ago there was no way to eat every time we got hungry. Today we eat at the slightest twinge of hunger, often eating heavily processed sugar packed foods with no nutritional value. The incomplete food hunger cycle Because there is no nutritional value in most if not all of the foods in your average local "super"market, the food does not turn off your hunger. As soon as your stomach empties, you are eating something else, always trying to satisfy the hunger. Since the hunger can never be satisfied, you keep eating and eating. Soon you are completely encased in fat, feel terrible and your risk of serious disease just skyrockets. What you can do ... Never eat before you expend some energy is some form in the morning. I accomplish this by running usually seven miles. When I first quit eating anything before I ran, the first few runs were a bit weak. I didn't feel good at about forty-five minutes into the run and would even feel a bit light-headed and hypoglycemic. I persisted and in about two weeks these feelings were completely gone and I could cruise an easy two hours with no additional fuels. The point here is that you have to enter into a glucagon state, start training your metabolism / enzyme systems and soon they will be able to supply the necessary energy for your run and you will be burning fat. Don't fill your tanks before you have emptied them and then some ... At some point in every day -spend some time in a glucagon state. That is the human biochemistry. To use the car analogy again think of filling your tank with gas, every day -the same amount. Each day you fill your gas tank with fifteen gallons of fuel. Some days you drive to Phoenix and back and use all this gas, but most days you just drive to the grocery and back. The next day you go for your fifteen gallons and you can only get five gallons in your tank. You put the other ten in two five gallon containers and put them in the trunk. Your car is full of gas -and you can't drive around the block The next day you drive to the cleaners and then stop to fill up again. Another fifteen gallons and this time you have to put twelve of them into separate containers. Now the trunk is full of gas containers and weighting down your car. Soon the back seat if full, the front seat is full and there is barely any room for you, the driver. If you don't expend the ingested energy, insulin will store it for you -somewhere and everywhere in and on your body. Learn to go a little beyond your ingested energy and keep those fat burning pathways open. You will feel better, work better and really reduce your risk of disease. Thanks for your attention. Copyright John Mericle M.D. 2005 All Right Reserved |
