Research methodologies in human nutrition 

Literature review on how percent body fat, physical activity and diet affect LDL oxidase/ LDL oxidation in obese and non-obese female students

Many people have associated the word obesity with being overweight and all manner of negative superlatives including being used as an offensive word. However, few people can truly define it and a great many do not view it as a medical condition just like any other common disease. With the huge stature that come with being overweight sometimes important for sports such as wrestling, there is sometimes a thin line between being considered normal or overweight. But the mechanics of obesity reveal a more sinister problem with debilitating. Obesity has led to loss of lives and is continuously cutting into the budget of both the citizens and the government in order to treat and manage it.

Obesity is the abnormal accumulation of excess body fats in the body to percentages or quantities which are deemed to be harmful to the body (Haslam and James 1198). However, the amount of body fat that is in excess must not be confused with those needed by the body for the storage of energy, insulation of the body especially against cold conditions and absorption of shock. It is what exceeds these quantities that qualify to be classified as a medical condition. This is the stage in which the accumulated fats begins to affect the general body functioning and processes thereby resulting to reduced life expectancy. Obesity is determined through the calculation of a person’s body mass index (BMI), which is calculated through the division of a person’s weight by the square of his or her height, usually in meters. When the resultant figure is more than 30, then the person is considered to be obese. And it is this BMI that distinguishes between being overweight and being obese. The oxidative activities of LBL oxidase which increases the accumulation of fats and lipids in the body therefore will increase the BMI of the body. However, waist circumference which calculated in relation to the height of the individual is used to determine obesity and overweight.

For an individual to be categorized as overweight they must have a BMI of 25 and above. Therefore, not all people who are overweight are obese but all people who are obese are considered to be overweight. However, the two medical conditions usually pose a health risk as more often than not, they have cited as one of the leading or predisposing factors to certain chronic diseases including, diabetes, and other cardiovascular diseases such as high blood pressure as well as cancer (WHO n.pgn.).

There are three major and commonly known causes of obesity. Excessive intake of energy rich foods, lack of regular exercises as well as genetic susceptibility remain the three major causes of obesity. Other than excessive uptake of fatty foods, genetics remain the most common cause of obesity. Poor or slow metabolism is also one of the causes of obesity. The main metabolizing agent in the body is the muscle which tends to burn more calories than other body tissues. Women usually have got lesser muscles than men and hence experience slower metabolism compared to the men. And this partly explains why women put on more weight than men. Losing of this accumulated fat due to reduced metabolism in women, is usually not for the women as with age, the body muscles are reduced and hence metabolism lowered even further. This clearly explains why women tend to suffer more from obesity than men. However, obesity has been classified by many researchers as a lifestyle disease because of its prevalence among those who live sedentary lives especially among children and adults who are inactive and spend most of their time watching television. That is, the potato coaches. Such individuals are at a higher risk of fat accumulation because they are not active enough to stretch the limits of their metabolism which would have enabled the body to break down fats instead of accumulating them.

Other than slow metabolism, genetics has also been determined as one of the cases of obesity. Individuals with obese parents are more likely to suffer from the condition more than other individuals with normal parents. Obesity has been found to affect various hormonal operations in the body and more especially those involved in the regulation of fat. Through polygenic inheritance, such hormones can be transferred from parents to their offspring in whom the condition will be manifested. Multifactorial inheritance is polygenic inheritance that also includes various interactions that individuals have with the environment. These multifactorial inheritances result into certain traits that produce continuous characteristics in the organisms in which they are manifested. Notably, the polymorphic genes that have been implicated in causing obesity are those that concerned with appetite and metabolism. According to study conducted by Loos and Bounchard and published in 2008, the presence of these genes increases the risk of obesity by a factor of 1.67 compared to those who lack the genes. This translates to an extra 3 to 4 kilograms in weight if the environment is conducive enough to promote binging or lifestyle which predisposes an individual to obesity such as smoking, taking of some prescription drugs and sedentary life. This is because such individuals have the risk allele which contains the FTO gene associated with regulating the body fat mass and in ultimately, obesity (Loos and Bouchard 246 – 50).

Also in a study conducted by Farooqi and O’Rahilly and published in 2006, it was established that gene mutation has a key role in causing obesity. The researchers established that 7% of children who are obese at a younger age, at below 10 years showed cases of single point gene mutation (Farooqi and O’Rahilly 712). Moreover, there are several syndromes which results from defective genes such as Prader-Willi syndrome and Cohen syndrome which researchers have associated with obesity. Of note is that these syndromes are caused by a change in gene sequence or mutation. The MOMO syndrome or Macrosomia, Obesity, Macrocephaly and Ocular syndrome is also closely associated with obesity. It is usually characterized by overgrowth, from birth, of the whole body including the head (Walley, Asher and Froguel 431 – 42). While individuals suffering from this condition may have relatively normal blood vessel sizes, the increased body size make it restively difficult for the blood vessels to bump blood throughout the body. This strains the heart and may wear down the arteries due to increased distance over which to pump blood. The wearing down of the heart because of over-activity can lead to heart failure and stroke. Moreover, insufficient supply of the blood to vital organs such brain can be fatal.

The oxidation of low-density lipoprotein (LDL) by LDL oxidase leads to the accumulation of lipids and blood in the bloodstream and other extracellular fluids. When lipids such as triglycerides and cholesterol accumulate within the endothelial walls of the blood vessels, they constrict leading to vascular dysfunction. The resulting thickening of the arterial walls is known as atherosclerosis or arteriosclerotic vascular disease. The resulting cardiovascular condition leads to difficult in pumping of blood by the arteries to the rest of the body. The inability of the heart to effectively pump blood throughout the body can lead to heart failure. In adverse cases where insufficient blood is pumped to the brain, stroke can occur. It can also be fatal. While increased levels of LDL also known as hyperlipoproteinemia type II can be triggered by other biochemical activities in the body, it is also hereditary. Individuals suffering from this condition, known as familial hypercholesterolemia (FH), can experience a severe case of obesity and the resultant effects such as cardiovascular diseases, stroke and heart failure and other diseases of the human system as it affects autoimmune surveillance.

With the numerous health risks and diseases associated with obesity, it can be concluded that obesity acts to significantly reduce life expectancy. Moreover, various effects have been found to result from this condition. One of the effects is high blood pressure. Increased fat in the body requires blood to be pumped to a wide area and distance in order for effective metabolism to take place in the body. This additional requirement of the blood vessels to transport more blood to the fat deposits put pressure on the blood vessels responsible for the transfer of this blood. This makes them work excessively more than they are supposed to resulting into the creation of pressure in the vessels responsible for such functions leading to high blood pressure. Moreover, the deposition of fat in the blood vessels decreases the size of their lumen forcing the aorta to pump extra hard in order for the blood to reach the rest of the body. In the end, this only causes pressure build up in the blood vessels and lack of enough supply of blood to the rest of the body and organ. If the shortage of blood supply occurs in the brain, then cases of stroke may be recorded (Haslam and James 1120 – 1123).

Once narrowed, there is the reduction of blood flow especially into the heart which might result in heart attack or chest pains, a condition known as angina. Cancer another leading cause of deaths today, is another obesity related condition which mostly affects women in which it causes breast cancer as well as that of the uterus and gallbladder. Obesity can also cause diabetes and more specifically type II diabetes which was initially a common disease in adults but has since been seen to affect children. Obesity generally has a limiting effect on insulin the hormone; the regulator of blood sugar level. Once obesity limits the operations of insulin, blood sugar level is most likely to elevate thereby resulting into type II diabetes condition. The condition is one of the leading causes of deaths today. Obesity also causes osteoporosis as the extra weight increases pressure on the bones causing cracks or even breakages. But most importantly, it negatively affects life expectancy and socialization (Haslam and James 1120 – 1123).

One important treatment and management option for obesity is lifestyle change which includes watching diet, increasing physical activities especially doing exercises and generally avoidance of sedentary lifestyle (Lau et al S1 – 11). Increase physical leads to the breakdown of the fats and lipids to produce energy. During strenuous activities, the body usually converts fats and lipids into adenosine triphosphate (ATP) after the exhaustion of glucose which is the first line source of energy for the body. This will lead to low levels of triglycerides, cholesterol and phospholipids which are transported by the LDL in the bloodstream and deposited on the endothelial walls of the blood vessels especially arteries and veins. The rate of LDL oxidation by LDL oxidase, like all enzymatic activities, is affected by the substrate concentration. Therefore, with reduced substrate levels within the bloodstream, the rate of activity of LDL oxidase with reduce significantly leading to the striking of a balance between vasodilation and vasoconstriction.

In case the condition is critical or the watching diet and lifestyle become impossible or unattainable for the patient, there are medications which can aid in weight loss such as Sibutramine (Rucker 1195).  These drugs act by increasing the body’s capability to break down fats and lipids to produce energy. Some of these drugs are also able o inhibit the activities of LDL oxidase and therefore reduce the rate at which triglycerides and cholesterol accumulates in the arteries.  Other drugs such as Ezetimibe are aimed at reducing the absorption of lipids such as cholesterol from the digested food substances. However, such options should be avoided at all cost because it will force the patient to be drug dependent in order to prevent weight gain.

The amount of food or substances assimilated into our bloodstream and into our bodies is also affected by the size or length of out digestive system. A reduction in the length of the digestive track can lead to reduced amounts of foods and therefore fats and lipids absorb into the body. Bariatric surgery, aimed at manipulating the amount of food one can take in a single eating occasion and ultimately, the amount of calories, is also another way for treating obesity. The surgery removes part of the intestines or stomach or even bypasses sections of the small intestines. This constricts the stomach and reduces the capacity of food one can eat. It therefore leads to a reduction in the amounts of fats and lipids that find their way into the digestive system and hence the body. However, such procedures are usually costly and unaffordable especially to a large section of the world’s population suffering from obesity: the poor. Moreover, there are inherent dangers that may arise from such procedures such as ulcerations and internal wounds. These can sources of other medical conditions such as cancer and ulcers.


Thirty (30) female university students were randomly selected as participants in the study. Their consents and that of the relevant authorities were sought and were given consent forms to sign. This was done after they were apprised on the nature and objectives of the study. This was done to address issues of ethics which may arise during and after the study. The random selection was done to ensure external validity of the data to be collected.


  • Tape measure
  • Bioelectrical impedance scale
  • Digital weighing scale
  • Calculator
  1. Percent body fat

The participants were asked to abstain from eating food or taking drinks for at least three hours before taking the measurements.

Each participant was asked to step on the bioelectrical impedance scale with both feet and the electrodes attached to each foot.

The time was noted and used to calculate the percent body fat.

  1. Waist circumference

Each of the participants was asked to breath normally during the exercise.

Using a tape measure, the circumference between the hip bone and the ribs was measured and recorded as the waist circumference.

  • Body mass index

The participants were asked to step on the scale and their weight was taken. Their height was also taken.

The weight of each of the participant by the square of her height in meters. The figure was recorded as the BMI.

The data collected from all the three measurements were then tabulated and further statistical analysis carried out on them.


Elliott, C.D. (2012). “Packaging Fun: Analyzing Supermarket Food Messages Targeted at Children.” Canadian Journal of Communication 37(2).

Farooqi, S. & O’Rahilly, S. (2006). “Genetics of obesity in humans”. Endocr. Rev. 27 (7): 710–18.

Haslam, DW. & James, WP. (2005). “Obesity”. Lancet 366 (9492): 1197–209.

Lau, D. C. et al. (2007). “2006 Canadian clinical practice guidelines on the management and prevention of obesity in adults and children summary”. CMAJ  176 (8): S1–13.

Milner, J.J. & Beck, M.A. (2012). “The impact of obesity on the immune response to infection. Proceedings of the Nutrition Society 71:298 – 306.

Kornfeld, J.W. et al. (2013). “Obesity-induced overexpression of miR-802 impairs glucose metabolism through silencing of Hnf1b.” Nature 494(7435): 111–115.

Loos, R.J. & Bouchard, C. (2008). “FTO: the first gene contributing to common forms of human obesity”. Obes Rev 9 (3): 246–50.

Rucker, D. et al. “Long term pharmacotherapy for obesity and overweight: updated meta-analysis”. BMJ 335 2007, (7631): 1194–99.

Walley, A.J., Asher, J.E. & Froguel, P. (2009). “The genetic contribution to non-syndromic human obesity”. Nat. Rev. Genet. 10(7): 431–42.

WHO. (2013).“Obesity. World Health Organization.