The Obesity Code: Chapter 2

Vegan Keto Book Club- "The Obesity Code" Chapter 2

Chapter 2 (titled "Inheriting Obesity") appropriately starts with the "nature versus nurture" question. 

It is no question that "obesity runs in families" according to Fung;  but the question is WHY.

It is certainly true that "families share genetic characteristics that may lead to obesity" (21).
However, Fung invites us to recall in chapter 1 that the obesity epidemic did not begin until the 70s.

Are we really supposed to believe that our genes spontaneously decided to make us obese in the last few decades? I think not.

BUT, the same foods that caused parents to be obese might be fed to children, and cause them to be obese (the nature vs. nurture debate!) Shared factors such as eating more frequently- with more meals eaten out, especially at fast food restaurants; increase in sugar,  high fructose corn syrup, and portion sizes; increased use of electronics- including computers and video game systems; and more time spent in cars and vehicles, lead many to believe that obesity is more about eating more and moving less, than it is anything to do with genetic factors. Fung begins the chapter exploring this debate.

He introduces us to a study on obesity, in which 540 Danish adult adoptees were compared to their adoptive and biological parents. Fung notes that, "If environmental factors were most important, then adoptees should resemble their adoptive parents. If genetic factors were most important, the adoptees should resemble their biological parents" (23).

Any guesses what they found...?

"No relationship whatsoever was discovered between the weight of the adoptive parents and the adoptee... In fact, the fattest adoptees had the thinnest adoptive parents" (23). SURPRISED???

What do you think they found comparing adoptees to their BIOLOGICAL parents...?

"The biological parents had very little or nothing to do with raising these children, or teaching them nutritonal values or attitudes toward exercise. Yet the tendency toward obesity followed them like ducklings. When you took a child away from obese parents and placed them into a "thin" household,  the child still became obese. What was going on?" (23).

WHAT WAS GOING ON, INDEED, DR. FUNG?!

Fung shares another study of identical twins (who share identical genetic material) and fraternal twins (with 25% shared genes) who were both reared apart, and reared together. 

What they found was shocking: "Approximately 70 percent of the variance in obesity is familial.

"Seventy percent of your tendency to gain weight is determined by your parentage. Obesity is overwhelmingly inherited" (24).

YET... If most of the obesity epidemic occurred in the last generation... what is going on?

The Thrifty-Gene Hypothesis

The "Thrifty- Gene hypothesis" became popular in the 1970's and hypothesizes that "all humans are evolutionary predisposed to gain weight as a survival mechanism" (24). Makes sense, right? Therefore, when we over-eat NOW, we are "simply following our genetic urge to gain fat" (24). Ehhhh....

I love Fung's writing style for metaphors like this: "Like a decomposing watermelon, this hypothesis seems quite reasonable on the surface. Cut a little deeper, and you find the rotten core" (24). 

Some highlights from Fung's rejection of this theory:

• The assumption that humans are genetically predisposed to overeat is incorrect. We have hormonal signals that tell us when we are full and stop us from eating until we explode.
• Hence, there is no genetic predisposition to overeating, but if you eat too much you will get sick and throw up... therefore, there is a powerful built-in protection AGAINST overeating.
• Cultures that HAD plenty of food, even way back when, did not find obesity prevalent until "the onset of industrialization and the Westernization of their traditional diet" (25). 
• THIS INCLUDES America, who has not had widespread famine since the Great Depression, yet only really struggled with obesity as a society since (again) 1970s... 
• Wild animals are not morbidly obese, even when they have an abundance of food. (instead of gaining FAT when there is a lot of food, they gain MORE ANIMALS...)
• There is no survival advantage to carrying a high body-fat percentage. Yes, bears gain weight before hibernation, but humans are not bears and we do not hibernate. And bears are not OBESE and do not have obesity related health conditions. They are fat for survival. Big difference. 

THEN Fung gives us a teaser that in part three we WILL see what the root cause of obesity is ("A complex hormonal imbalance with high blood insulin as its central feature" [26]).

The reason we see genetic connections, rather than environmental, is because the "hormonal profile of a baby is influenced by the environment in the mother's body before birth, setting up a tendency for high insulin levels and associated obesity later in life" (26). 

And then Fung, king of the cliffhanger, leaves us with this: "Inherited factors account for only 70% of the tendency to obesity that we observe. The other 30 percent of factors are under our control" (26). 

And of course you have to keep reading to find out what those factors are and how to control them!

You can say a lot of things about Fung, but he sure knows how to hook an audience! Or, maybe it's because for once we are finally NOT being told "eat less and exercise more. If you're fat it's because you are lazy and have no self control! CONTROL YOURSELF, FAT PERSON!" And that feels good. 

Until Next Time... 

That was a pretty short chapter... I'm going to see if the book club wants to move through the book a little bit faster! Stay tuned; the next summary might be more than just one chapter! We shall see!

Vegan Keto Madi