Genes, yes, but obesity pandemic mostly down to diet: study

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A three-fold jump since 1975 in the percentage of adults worldwide who are obese has been driven mainly by a shift in diet and lack of exercise, but genes do play a role as well, according a large-scale study published Thursday.

For people genetically predisposed to a wider girth, these compounded the problem, resulting in an even higher rate of weight gain, researchers reported in The BMJ, a peer-reviewed .

The standard measure for obesity, the Body-Mass Index (BMI), is calculated on the basis of weight and height.

A BMI of 25 up to 30 means that one is overweight. Thirty and above corresponds to obesity, a major risk factor for heart attacks, stroke, diabetes and some cancers.

About four percent of in the mid-1970s had a BMI of 30 or higher. By 2016, that share had risen to 13 percent (11 for men and 15 for women), according to the World Health Organization.

There are currently about two billion people 18 and older—39 percent of all adults—with a BMI above the "overweight" threshold of 25, and 700 million of them are clinically obese.

The prevalence of excess weight has risen even more dramatically among children, from four percent in 1975 to over 18 percent in 2016.

To tease out the relative impact of environment and genes on obesity, scientists led by Maria Brandkvist at the Norwegian University of Science and Technology combed through data on nearly 120,000 people in Norway whose height and weight were regularly measured between 1963 and 2008.

Adults began tipping the scales at significantly higher weights in the 1980s and 1990s, they found.

Those born after 1970 were far more likely to have a substantially higher BMI as young adults than earlier generations.

'Obesogenic' environment

Half of the people monitored were divided into five groups depending on their to obesity.

Comparing the two groups at the extremes, the researchers found, for example, that 35-year-old men with genetic variants known to favour were already heavier in the mid-1960s than men the same age without those fat-inducing genes.

Four decades later—even as obesity rates increased across the board—that gap nearly doubled.

Women showed the same trend, though the increase over time was somewhat smaller.

"Genetic predisposition would make a 35-year old man of average height 3.9 kilos heavier than his genetically protected peers in the 1960s," explained Brandkvist.

"In Norway today, his vulnerable genes would make him more than 6.8 kg heavier."

In addition, he will have gained an extra 7.1 kilos "simply as a result of living in our 'obesogenic' environment," she added.

"This man's 13.9 kg excess is caused mostly by today's unhealthy lifestyle, but also by how his genes interplay with the environment."

While the correlation between the genetic profiles and degree of was strong, the study—by its nature—cannot determine a direct cause-and-effect relationship, the authors caution.

Only clinical trials can highlight causal relationships, but for many areas of interest such experiments are not possible with humans, for both practical and ethical reasons.

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Substantial increase in body weight since 1960s due to interplay between genes and environment

Journal information: British Medical Journal (BMJ)

© 2019 AFP

Citation: Genes, yes, but obesity pandemic mostly down to diet: study (2019, July 4) retrieved 15 October 2019 from
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Jul 05, 2019
You can blame a lot of this on the US Government's food pyramid. The whole bottom consists of high glycemic index carbohydrates which induce weight gain and diabetes. Flip the pyramid 180 degrees (Keto) diet and you have solved the problem. Once you realize that carbs are as addictive as heroin the answer to weight gain becomes very clear.

Jul 05, 2019
Issuing a DMCA takedown for this photo of Randy Bobandy's gut.

Jul 06, 2019
This is assuming that diet is not genetically determined. That's a big assumption. Every freshman biology course uses the simple genetic trait of phenolpthalein tasting versus non-tasting to demonstrate that the sense of taste differs genetically. Most human traits are coded by multiple genes and there's every reason to believe that human taste sensitivity is the same. In other words, it's more likely than not that the taste for different types of foods is highly heritable.

Jul 06, 2019
It has GOT to be more than diet.

" increasing amount of scientific evidence suggesting that endocrine disrupting chemicals (EDCs) may also play a role. Two terms have been coined in describing the role of certain chemicals in metabolism and obesity.

"Obesogens are chemicals that can enter the body and disrupt normal lipid metabolism, which can lead to obesity.
Diabetogens are chemicals that can enter the body and kill β-cells or disrupt their function and interfere with normal energy metabolism, which can lead to diabetes."

-Obesity... a side effect of efforts to reduce the birthrate by any and all means. Obesity itself lowers fertility rates and causes miscarriages, birth defects, generational metabolic syndrome.

Fat people also make less money on average and can't afford as many children. They are sick more often and die sooner, making orphans of the few children they do bear.

Jul 06, 2019
In case you doubt;

"Obesity increases the risk of various pregnancy complications, including: The risk of miscarriage, stillbirth and recurrent miscarriage. Gestational diabetes..."

"Babies born to mothers who are obese... are at increased risk for a range of major birth defects, new research shows... linked to an increase in birth defects involving the brain and spinal cord."

"The association between obesity and lower fertility rate has been shown in several studies, and it has been shown that obesity in early adulthood alters the reproductive functions."

"Fat people earn less and have a harder time finding work... especially true for women..."

"obese individuals took four more sick days per year on average than those of a healthy weight... 300,000 deaths per year are due to the obesity epidemic..."

"A child with one obese parent has a 50% chance of being obese. When both parents are obese, their children have an 80% chance of obesity"

-Looks like a Plan to me.

Jul 07, 2019
Otto diet is the problem for most people. If you eat starches and sugars (high glycemic index carbohydrates) they enter your bloodstream as glucose very quickly. You use this glucose for energy and any excess is stored as fat. Any fats that you consume at that time turns to stored fat also since your body prefers to process carbs and not fats. When this spike in blood sugar returns to normal hunger pains and cravings begin. Now in the keto diet since you are not consuming sugars and starches your body has to process fat in order to create glucose. It processes only enough fat to keep glucose levels stable. Thus hunger pains and cravings are greatly reduced because body fat is always available to be processed when needed.

Jul 07, 2019
In addition, your body has to be trained to use body fat as a source of energy. It will always burn carbs first if they are available. It will always demand carbs by creating hard to ignore hunger pains before it will acquiesce to burn body fat. Once trained to burn fat only hunger pains are much diminished.

Jul 10, 2019
Otto diet is the problem for most people. If you eat starches and sugars (high glycemic index carbohydrates) they enter your bloodstream as glucose very blah
You really think I'm going to value some anonymous, unsubstantiated OPINION? Why waste the effort? It's only annoying at best.

If you think your OPINIONS are worth anything then back them up with sources or admit they're worthless.

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