Question

A study in England tested 20,430 people for alleles of 12 genes known to increase risk of becoming obese. ( Each person had 24 alleles assessed, 12 from each parent). Although the number of risk alleles correlated to BMI, the more a person excrised, the lower the BMI. Do these finding support a genetic determinstic view of the trait of body weight, or not? Cite a reason for your answer.

Answer 1

An allele is a variant of a given gene.
No,although the number of risk alleles correlated to BMI(the more a person execised ,he cannot lower the BMIwhen a person trying to loseweight who carry abnormal PPAR gamma gene ,a high fat diet can hinder weight loss)

Anywhere between 30 -70 % of our body weight is influenced by our genes.And tendency to be obese is quite common among as evident in high obesity rates globally.
this has led to the proposal of what is known as thrifty gene hypothesis.according to this hypothesis,for most our existence as aspecies,food was scarce,necessitating opportunistic eating and storage of calories in the form of reserve for leaner times.
an example is children of overweight or obese parents tend to be overweight too.
other study carried out on twins help understand the association between genes and body weight better.Monozygotic or identical twins share same genes and te same parental enviroment and have similar body weight while dizygotic twins,on the other hand ,share same parental enironment but not the genes and could vary significantly in bodyweight.

Another fact that determines body weight is our body's ability to store excess calories as fat and subsequent utilization of calories when needed.The PPAR gamma genes are associated with this cycle and variation of these genes determine how much fat is stored and how quickly our body breaks down such fat for energy.
PPAR gamma plays an important rolein the physiological response to dietary fat in humans.It mediates adipocytes differentiaion and fat storage base on the diet.
Body mass index(BMI)is an important indicator of obesity and the dietary fat that is consumed translates into BMI depending upon the type of PPAR gamma gene present in the body.A variant of the PPAR gamma gene is associated with higher BMIwhen the total fat was high.
people with abnormal PPAR gamma gene and who have a high fat diet are found to be more obese than people who carry the normal gene.The abnormal PPAR gamma gene is also associated with insulin resistance,which causes to obesity.

EXERCISE AND BMI:
when a person trying to loseweight who carry abnormal PPAR gamma gene ,a high fat diet can hinder weight loss. Such individuals would benefit from a low fat diet.