Biochemical Principles - Essay Example

Biochemical Principles How the body metabolises carbohydrates Carbohydrates have three key elements: hydrogen, oxygen and carbon with two hydrogen atoms for every one carbon atom. They all ascribe to the following formula (CnH2nOn). Each carbohydrate has simple sugars which determine its classification. Those compounds with several simple sugars are polysaccharides while the ones with only two are classified as disaccharides. Items with one simple sugar are monosaccharides and a typical example is glucose. This is the most common type of carbohydrate found in mammalian bodies and is what medical professionals call blood sugar. The following is the molecular structure of the three common carbohydrates: glucose, fructose and galactose. glucose fructose galactose Synthesis of energy molecules is the ultimate goal of carbohydrate metabolism. Therefore, one may define it as the process by which carbohydrates are broken down into simpler molecules which result in the release of energy in the form of adenosinetriphosphate or ATP. The body requires energy in order to function. Any biological process or activity including respiration requires energy. Therefore, carbohydrate metabolism sustains mammalian life. The process often begins in the small intestine. When a person consumes carbohydrates, their body works on larger saccharides to convert them into smaller molecules. In the event that simple monosaccharides are already present, they will pass directly from the capillaries of the small intestine into the bloodstream. However, for complex carbohydrates like most starches including bread and potatoes, the enzyme amylase will work on them in order to convert them into tri and disaccharides. The latter molecules will then be hydrolyzed to glucose. Some mammals like man cannot digest beta glucose which is present in some starches. However, ruminants have the capacity to digest cellulose because their enzymes work on beta glucose. The hormones insulin, glucagon and epinephrine control the metabolism of carbohydrates. Usually, when the body has excess glucose, insulin will cause uptake of this excess into liver fat tissue or muscles. Glucose is in the form of glycogen when in the liver and muscles. This conversion of glucose into glycogen occurs through glycogenesis. Conversely when glucose is in low supply in the blood, it is obtained through the breakdown of glycogen which is supported by the hormone glucagon. Glycolysis is the key process in energy synthesis or carbohydrate metabolism. The process involves the conversion of glucose into pyruvate as well as ATP or energy. Therefore, one may state that pyruvate and energy are the main products of carbohydrate metabolism. This process begins with the conversion of glucose into an intermediate product known as glucose-6 phosphate. As this process occurs, 2ATP molecules are converted into 2 ADP molecules. The latter molecule is then converted into fructose-6-phospate. This process causes the conversion of one ATP molecule into one ADP molecule. This molecule then becomes fructose 1,6 biphosphate which eventually changes to two glyceraldehydes-3-phospate molecules. These are converted into 1, 3 biphosphoglycerate and NADH. NADH is a combination of 2 NAD molecules and 2 phospate ones. The 1,3 biphosphoglycerate is changed into 3-phosphoglycerate. This process entails the conversion of 2ADP molecules into ATP molecules. The 3-phosphoglycerate will become 2-phosphoglycerate and form two phosphoenolpyruvate molecules. These will finally be converted into pyruvate which also entails the conversion of 2ADP molecules into 2ATP molecules. The latter is what provides quick energy for external and internal activities in the body. Major claims in a scientific journal and a nutritional blog The basic claim in the nutritional blog is that all that matters in weight loss is the calories a person consumes. The writer believes that no other dietary factors are as important as the quantity of calories consumed. He goes on to say that this is the only thing that will truly cause a person to achieve their weight loss goals. The calories-in versus calories-out premise is what many weight loss programs depend on when giving advice about dietary consumption. It is a balancing act that the body wrestles with every time a person attempts to manage their body mass. In the nutritional blog, the author claims that all food items a person consumes determine the total amount of calories in. He also adds that the amount of energy used by the body is called the amount of calories out. These may refer to the calories consumed during exercise as well as when carrying out normal activities like standing up. Furthermore, he adds that breathing, food digestion and blood pumping all constitute the calories out. Since the body burns or consumes those calories then they are expended out of the body (Calorie Counter, 2013). In the nutritional blog, it is also stated that when a calorie surplus occurs between calories in and out, a person will either gain muscle or fat thus gain weight. Conversely, if a calorie deficit exists, in that the calories out exceed the calories in then muscle loss or fat loss may take place. Weight maintenance takes place when no difference occurs between calories in and calories out. The author believes that this premise is supported by basic laws of thermodynamics. He adds that if a person consumes more calories than the body requires, then it will not burn it (convert it to energy). In essence, the body has already taken care of its internal physiological processes as well as typical activities like sitting, so it will simply store these extra calories. Storage could take place in the form of fats or muscle. However, he also adds that sometimes a person can consume excess calories and these may be used to build muscle tissue. The difference between these two arises when a person has an exercise regimen that incorporates muscle-building activities. The scientific journal questions this simple assumption. Manninen (2006) believes that there is more to weight loss than just calories. Here, it is claimed that the nature of nutritional content affects how effective a diet plan is. A number of researches done on the benefits of low carbohydrate diets have shown that such diets are metabolically advantageous since body mass index is greatly reduced in low cab diets. One such study involved three diets in which the subjects all ate the same number of calories; that is 1,800 Kcal per day for nine weeks. It was found that persons in the high carbohydrate category only recorded 75% weight loss. Those in the intermediate category recorded 84% weight loss while those in the low carbohydrate diet reported 95% weight loss. Even persons who consume slightly higher calories have a greater chance of weight loss if they stick to a low carbohydrate diet. This author was thus saying that calories alone are insufficient for weight loss. One must look at the nutritional content of the food as well as the presence of certain enzymes in the body. Consumption of good fat has been shown to be an advantage in the paper. The author quotes a study in which the subjects were subjected to similar protein and calorie intakes. However, in one group, the participants consumed a low carbohydrate diet while in the other group individuals consumed a low fat diet. Weight loss was much greater in the low carbohydrate diet than the low fat diet. This indicated that fat does have a positive role to play in weight loss so it should not be restricted severely. Additionally, the scientific journal considers carbohydrate metabolism and the effect of hormones on this process. Since insulin affects the conversion of excess glucose, it will thus determine the extent to which the carbohydrate will be taken up by muscles and liver. This is the reason why some individuals will be highly vulnerable to obesity while others will not be regardless of the diet they consume. In the journal, it is explained that absence of insulin receptors inside fat tissue shields mice from obesity in spite of the calories they eat. Similar results are also reported among mice without the enzyme acyl-coenzyme. It is responsible for catalyzation of triacylglycerol; therefore its absence implies that people with these metabolic deficiencies will consume as much calories as possible and still not gain weight. Comparison of the claims In essence, the nutritional blog is saying that a calorie is just a calorie while the scientific journal shows that a calorie is not just a calorie. A significant difference in weight management arises when one considers the quantity as well as the nature of foods consumed. The nutritional blog seems to have ignored one of these while the scientific journal accommodates all parts of the equation. When searching for a valid scientific study, one ought to think about the full picture. If the assertions made in an article leave out critical aspects of the topic, then they could be wrong. The relevance of a report must be assessed in light of what other scientists have done on the same. If a finding opposes most recent research, then there could be chances that the finding was based on chance or experimental error than direct cause and effect relationships between the variables. One ought to think of scientific insights in light of where the field is moving currently. It appears that the blog is not moving with the times. Many scientific experts in the world of nutrition now believe that there is more to weight loss than just the amount of calories that one takes. Therefore, since the assertions in the blog seem to be contradicting recent findings, without any valid explanations, then their validity may be questioned. The claims in the nutritional blogs are based on pseudo science while the ones in the scientific journal are not. In the nutritional blog, the writer has looked at a scientific process without considering all the micro processes involved. A good scientific process is one in which all the variables are considered when making final deductions. Therefore, the role of macronutrients like fat, protein and starch ought to be regarded seriously when making any assertions about weight loss. If it is possible to alter the macronutrient levels of a certain diet and still maintain the same weight, then calories consumed would have been the only thing that matters. However, experiments quoted in the scientific journal have shown that the extent of weight gain or loss is affected by the nature of nutrients in the diet. This is the reason why some people register greater success in calorie control than other. The scientific journal was not refuting the calories-in-calories-out theory; it was simply giving a holistic picture of the theory. The scientific journal relies on experiments in which potential confounding factors are minimised when analysing a phenomenon. For instance, when analysing the effect of carbohydrate levels on weight loss, scientists kept the quantity of calories consumed constant as well as the level of protein the same; the only variant was carbohydrates. It should be noted that proteins support tissue regeneration and help in organ repair and function. Therefore, lean mass will be higher in a medium or high protein diet than a low protein one. The findings cited in the scientific journal were also measured, repeated and confirmed by other analysts. However, the nutritional blog only looked at weight loss from a superficial point of view. Causes and effects were linked together without consideration of the intermediate processes. Issues such as insulin resistance were not mentioned in the article yet they may change one’s metabolism significantly. Therefore, this blog was misleading and based on Standard dogma. The latter quality is quite common in pseudo science. Instead of embracing new scientific findings concerning a particular topic, pseudo scientists prefer to cling to old fads about the same. They rarely progress and will not uncover new information. Conversely, science values new and supported information. In nutrition and weight loss, many scientists claimed that eating too much food led to obesity. If one can solve the energy imbalance then they would lose weight. However, new experiments showed that eating wrong foods like easily-digested or highly processes carbohydrates is a problem. Others also altered micronutrient levels and found significant differences in degree of weight loss. Therefore, conventional thinking on the topic was questioned and now progress is evident. The scientific journal represents the latter view while the blog represents the pseudoscientific perspective. References Calorie Counter, 2013. Daily calorie intake- Why calories in versus calories out is the key to your diet. [online] Available at: http://www.acaloriecounter.com/diet/daily-calorie-intake-calories-in-vs-calories-out/ [Accessed 21 January 2013]. Manninen, A., 2006. Metabollic advantage of low carbohydrate diets: A calorie is still not a calorie. American Journals of Clinical Nutrition, 83(6), pp. 1442-1443. Read More