Understand what Calories mean

What exactly are calories? Many people will answer this question by saying that calories are bad, or that whatever they are you have to watch them, or with a blank stare. When attempting to lose weight, gain weight, or improve your health through diet, it is essential to understand exactly what calories are and why you need to be aware of them. Calories are a unit of energy. One calorie is defined as the amount of heat required to raise one gram of water one degree Celsius. A food calorie is actually a kilocalorie, or one thousand calories,
and is the amount of heat required to raise one kilogramof water one degree Celsius (or 2.2 pounds of water 1.8 degrees Fahrenheit). To put it in practical terms, in order toheat a liter of water from room temperature (25 degrees Celsius or 77degrees Fahrenheit) to boiling (100 degrees Celsius or 212 degrees Fahrenheit) you must add 75,000 calories, or 75 food calories. (from here on "calorie" will always mean a food calorie, or kilocalorie) This may seem unrelated to your body, but remember that your body temperature has to be at 98.6 degrees Fahrenheit (37 degrees Celsius), so your body must constantly use energy to maintain this temperature. The colder the environment is, the more energy yourbody must use to maintain your core body temperature. This is one of the main reasons why people often want to eat more in winter - their bodies require more energy to maintain theircore temperatures. Maintaining your core temperature is the first part of your basal metabolic rate . Your basal metabolic rate is the amount of energy, that is, the numberof calories, that your body must have in order to survive. If you consume less calories than your basal metabolic rate requires, you are literally starving. Continuing to consume less calories than your basal metabolic rate requires will eventuallyresult in death by starvation. What is your basal metabolic rate? This number is calculated based on your current body mass, that is, how much you weigh, your height, your age, as well as your body composition. In order to maintain your current weight, assuming absolutely no exercise (as if you just lay in bed asleep all day) you require acertain number of calories to maintaincore temperature and allow your internal organs to operate. These are the calories that are used to keep your heart pumping, to keep your lungs breathing, produce new blood cells, filter waste out of your bloodstream, maintain your brain, and all the internal workings of your body that are automatic. There are many free online basal metabolic rate calculators, like this one , however the most accurate calculation takes into account how much lean body mass you have. Lean body mass is the weight you have that is NOT stored fat, and in order to figure out that number you have to have a measuring device at home, such as a scale that tells you your body fat percentage (if you have 30% body fat,then your lean body mass is 70% of your weight). If you know your lean body mass, you can use this formula to calculate your basal metabolic rate: Basal Metabolic Rate = 370 + (21.6 x lean body mass in kg) Now that you know your basal metabolic rate, you know how many calories are required for you to survive. This however is the absolute minimum number of calories you need. Calories are your only source of energy. If you want to climb a flight of stairs, carry your groceries, play guitar, read,or do anything, it requires energy to do so. The only way to have energy todo these things is to consume calories. Plants can acquire energy from the sun through photosynthesis,for humans and animals, the only waywe can get the energy we need is by eating. Not only must you eat enoughcalories to fulfill your basal metabolic rate requirements, you must also eat enough to fuel any activities that you partake in. Based on your activity level, you can calculate how many calories in total that you require daily by multiplying your basal metabolic rate by 1.2 for sedentary people, to 1.9 for active people. The absolute best way to figure this out is to see a doctor who specializes in nutrition. This is difficult to calculate accurately at home, because your metabolism (the rate at which your body burns energy) beyond your basal metabolic rate can be affected by other factors than just your size. For example, if youhave hypothyroidism (underactive thyroid gland) your metabolism will be slower than the average person's. For a rough approximation, take your basal metabolic rate, and multiply that by 1.2 if you are sedentary, 1.5 if you are moderately active, and 1.9 if you exercise regularly. Your calorie consumption is only part of your nutrition. A popular saying among nutritionists is "not all calories are created equal." The most important thing to remember is that calories are only a measure of energy. Calories have nothing to do with what your body needs besides your energy needs. Thenutritional requirements of your bodycan be grouped into three categories:fats, carbohydrates, and proteins. Your body has different needs for each of these groups, and because of personal body chemistry, the amounts you need of each group can vary. In reference to calories, however, it is imporant to understandhow each of these categories supply energy. Fats contain more calories than proteins or carbohydrates. Each gram of fat will give you 9 calories. The reason that they give more energy per gram than proteins or carbohydrates have to do with their chemical structure. In biochemistry (the chemistry of biological molecules) fats are known as triglycerides. They are made up of three fatty acid chains attached to a glycerol backbone. What this means isthat each molecule of fat has a lot of chemical bonds, more chemical bonds than is found in proteins or carbohydrates, and the way your body extracts energy is by breaking these bonds. More bonds = more energy = more calories. There are some fats that your body cannot fully process for energy. These are called trans fats, because they contain a kind of bond called a trans bond. Naturally occuring fats will only have cis bonds (cis and trans are chemical terms referring to double bonds, you can look these up online or in a chemistry textbook). Your body is only designed to break down the naturally occuring cis bonds and are unable to process trans bonds, with the result that these so called trans fats will stay in your bloodstream, clogging your arteries. Fat is also how your body stores excess energy and serves as the body's insulation. You must have some body fat for skin and hair health, and as a buffere for disease. Women must have a certain percentage of body fat in order to reproduce, which is why extremely malnourished or extremely lean women will not have a menstrual cycle. Fats in your diet also are essential to absorb and process certain vitamins your body needs, specifically vitamins A, D, E, and K. There are also essential fatty acids, which are fats that your body needs to function but cannot produce itself - they must be consumed as food. Carbohydrates are your body's immediate source of energy. Each gram of carbohydrates will give you 4 calories. Carbohydrates are small molecules made up of carbon, hydrogen, and oxygen (carbo- from carbon, hydrate from hydrogen and oxygen). They contain fewer bonds than fats as they are smaller molecules, but are much easier to break down for immediate energy. The smaller a molecule is, the easier it is to break down; this is the difference between "simple" carbohydrates and "complex" carbohydrates. Simple carbohydrates will be broken down almost immediately, these are what we usually refer to as simple sugars. Complex carbohydrates, which are found in coarse grains such as steel-cut oatmeal, take longer to break down and will provide a more sustained energy supply. Unlike fats and proteins, carbohydrates do not provide anything that the body cannot manufacture itself, however, itputs a lot of strain on the organs without carbohydrates because the only form of energy that your brain uses is from carbohydrates. While fatsprovide a lot of energy when broken down, in order to be used in your brain they must be converted to glucose, a simple carbohydrate. It is far easier to obtain glucose for mental function from carbohydrates than from fats or proteins. Similarly, when doing any form of exercise, carbohydrates provide a much more efficient source of energy, and in order to use fats as an energy source during exercise, they must first be broken down into carbohydrates. Proteins are your body's building blocks. Each gram of protein will give you 4 calories. You have probably heard thephrase "essential amino acids" before. Amino acids are proteins. All proteins, in fact, are amino acids. Proteins are used in all parts of the body. They provide the structure for your cells, provide your body with movement in the form of your muscles, and make up the enzymes your body produces in order to run chemical reactions (this means that inorder to process fats and carbohydrates for energy, you must have proteins). Essential amino acids are protiens that, like essential fats, the body cannot produce on its own -they must be consumed. Because your entire body is constructed from proteins, they are more important as building blocks than as energy - however, if you do not consume enough calories, your body will begin to eat the protein that makes it up forenergy. Death by starvation often occurs when the body begins to cannibalize the heart muscle for energy. Calorie storage - how your body makes fat Your body needs certain fats for its internal processes, but if you consume more energy (calories) than you need, your body does not just getrid of them. Your body will store excess calories in the form of body fat. These are calories that your bodyis hanging on to as a source of energyto use if there is a lack of energy consumption. Again, as your body cannot produce certain fats, having body fat does not mean you do not need to eat fats. You still must consume certain fats for healthy bodyfunction. Your body will dip into its energy reserve when you run out of immediate energy to use. This means that your body will only use its storedfat when you do not consume enoughcalories to match your metabolism (your activity plus your basal metabolic rate). In order to lose excess body fat, you have to solve theenergy equation. One gram of fat is equal to nine calories. Therefore to use up one kilogram of stored fat, youmust have a difference of 9000 calories between what you eat and what you use. (Or 3500 calories for one pound). One of the problems many people have is so-called "water weight," which is weight caused not by fat but by fluid retained in your body. Because stored fat is living tissue, it must have blood flow to it, and is therefore filled with fluid. However despite issues of water weight (which is affected by how much water you drink and your electrolyte balance, which is the concentration of various salts and ions in your body), the formula remains the same. It is not possible tolose fat or muscle if the calories you consume are greater than your energy expenditure, and it is not possible to gain fat or muscle if the calories you consume are less than your energy expenditure. Your actual weight may not change because of retained fluids, or changes in body composition (muscle is denser tissue than fat, so building muscle will causeyour weight to go up even while your body's fat stores are depleted), but unless your body is a nuclear reactor, you cannot gain more than you eat, and you cannot lose more than you expend. Calories are only numbers. Calories are only useful as part of a thermodynamic equation, that is, your energy in versus your energy out. In order to maintain a healthy weight, you must balance this equation so that your energy expenditure matches your energy consumption. However, knowing how many calories you eat will only take you so far. Because your body needs certain types of molecules to function correctly, you must balance your calories with the source of thosecalories. This is where nutrition comes into play. It is essential for your health that you ensure the fuel for your body is not only the right amount, but the right type. And remember, since each individual's body chemistry is different, all of the calculations that you do are subject tochange. You need to be aware of your own body's energy needs and ensure they are being met, and also that in order to keep your body from slowing its metabolism in an effort to stave off starvation, you must meet your basal metabolic rate requirements. Also, as your body's composition changes, so will your metabolism. Whether your goal is to lose weight, build muscle, or just become healthier, remember that food is your only source of energy, but energy is not all that it is. Caloriesare not to be feared or avoided, it is the source of those calories that is essential for your health.