Since 1975, there has been an influx in the number of obese adults. According to surveys, the rise in the number of obese cases amounts to a three-fold increase. Experts say that even if obesity has been driven mainly by the structure of one's diet and lack of exercise, it is very important to note that genes also play a huge role.

According to a recently published study, the unhealthy lifestyle is even harder to resist, especially for people who are genetically predisposed to have a wider girth. The study highlights how genetic predisposition could lead to higher rates of weight gain.

As the standard measure for a body mass index (BMI) is calculated on the basis of height and weight, for a person to reach a BMI of 20 to 30 would mean the person is overweight, while 30 and above classifies a person as obese. Previous studies have shown that obesity is a major risk factor for heart attacks, diabetes, stroke, and some cancers.

Surveys have shown that about 4% of adults had a BMI of 30 or higher during the mid-1970s. The rate would rise to 13% by 2016 according to the World Health Organization (WHO). Currently, overweight cases account for 39% of adults. This covers an age group of 18 years and older with a count of about 2 billion people. From that count, 700 million are clinically obese.

Maria Brandkvist, from the Norwegian University of Science and Technology, worked with a group of scientists to study the relative impact of one's environment and genes on obesity by reviewing the data of nearly 120,000 people in Norway whose height and weight regularly measured from 1963 to 2008.

50% of the individuals that were monitored were divided into five groups depending on the degree of their genetic susceptibility to obesity. The team compared the two groups from the extreme sides for the study, where they found out that most 35-year-old men having the genetic variants that favor weight gain were already heavier in the 1960s as compared to men of the same age who did not have genes that induced a fat physique. According to scientists, the same pattern is followed by women. However, for women, the increase in obesity cases are smaller.

Even if the scientists presented a strong link between the genetic profiles and the degree of obesity, The study authors have cautioned the public that the study cannot determine the direct cause and effect relationship for the topic, and more research needs to be conducted.