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Obesity and genes: the skinny of it

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Summary

This article explores the role of genetics in obesity and how it affects individual variation in weight gain and loss. It looks at the concept of "thrifty" vs. "spendthrift" metabolisms, and how the introduction of calorie-dense foods in the 20th century has made certain genes maladaptive in our current environment. It also discusses the difference in metabolism between obese and non-obese people, and how some people with bad genetics are almost doomed to be overweight. It also looks at the example of an individual with superior genetics who is able to maintain a very low weight by consuming a relatively normal amount of food. The article concludes by emphasizing the need to recognize obesity as both a lifestyle and a biological problem, and to treat it as such.

Q&As

How do genes affect individual phenotypic variation when environment is held constant?
Genes play an inescapable role in explaining individual phenotypic variation when environment is held constant.

What is the difference between a 'thrifty' and 'spendthrift' metabolism?
A 'thrifty' metabolism is one in which the person loses less weight during calorie-reduction and their metabolism decreases the most during fasting, while a 'spendthrift' metabolism is one in which the person loses the most weight and their metabolism decreases the least during fasting.

How much of a role do genetics play in explaining obesity?
Genetics play a significant role in explaining obesity, as many obese individuals likely have slow metabolisms, too much ghrelin, insufficient leptin, etc. which can lead to them being too hungry all the time, or not getting full despite eating large quantities of food, or burning too few of calories consumed.

What is an example of an individual with superior genetics for weight loss?
An example of an individual with superior genetics for weight loss is Michael Rae, who is part of a NYC dieting social circle and consumes 1,913 calories a day while maintaining a skeleton-thin BMI of 15.6.

How might understanding the role of genetics in obesity help address the issue in America?
Understanding the role of genetics in obesity can help address the issue in America by recognizing that obesity is not just a lifestyle problem but also a biological one, and must be treated as such like any other disease.

AI Comments

👍 This article offers a comprehensive look at the role of genetics in obesity, with a range of evidence and examples to illustrate its points.

👎 This article lacks an actionable solution to the obesity epidemic, which can leave readers feeling helpless and hopeless.

AI Discussion

Me: It's about the role of genes in explaining individual phenotypic variation when environment is held constant. It talks about why some people get much fatter than others while having access to the same food, and why some people lose or gain weight more easily than others. It also talks about the implications of the 20th century introduction of hyper-palatable, calorie-dense foods and how this makes certain genes maladaptive in our present environment of abundance.

Friend: Wow, that's interesting. So what are the implications of this?

Me: Well, it implies that not everyone converts or partitions the same amount of calories into equal proportions of stored fat and spent energy. Some people may have what's called a "thrifty" metabolism, where their bodies are better at turning food into fat, or need very little energy to run. This means that for some people, dieting may be more difficult, as they need to cut more calories than predicted to lose weight. It also means that those with good genetics for weight loss can stay slim without having to reduce calories much. Finally, it means that the obesity problem in America needs to be treated as a biological problem as well as a lifestyle problem.

Action items

Research the effects of calorie restriction on weight loss and longevity.
Learn more about the metabolic phenotypes of thrifty and spendthrift metabolisms.
Explore the genetic differences between individuals who are able to maintain a healthy weight and those who struggle with obesity.

Technical terms

Phenotypic Variation: The differences in physical characteristics between individuals of the same species.
Ghrelin: A hormone that is released by the stomach and stimulates hunger.
Leptin: A hormone that is released by fat cells and signals to the brain that the body has had enough to eat.
Metabolic Adaptation: The body's ability to adjust its metabolism in response to changes in diet or activity level.
Thrifty Metabolism: A type of metabolism that is more efficient at storing calories as fat, making it harder to lose weight.
Spendthrift Metabolism: A type of metabolism that is less efficient at storing calories as fat, making it easier to lose weight.
Indirect Calorimeter: A device used to measure the amount of energy a person is expending.
TDEE: Total Daily Energy Expenditure, the amount of energy a person needs to maintain their current weight.
Cachexia: A condition characterized by extreme weight loss and muscle wasting.