Chapter Twenty-one THE CARBOHYDRATE HYPOTHESIS, I: FAT METABOLISM Flashcards
What is the main focus of obesity research according to Hilde Bruch?
Examination of abnormalities of fat metabolism
Bruch stated that excessive accumulation of fat is the underlying abnormality of obesity.
Who presented the presidential address at the Endocrinology Society in 1962?
Edwin Astwood
Astwood was not primarily known as an obesity researcher.
What hormone did Edwin Astwood discover?
Luteotropin (now known as luteinizing hormone)
Astwood also created the standard technique for purifying pituitary hormones.
How did Astwood view obesity?
As a genetic disorder
He believed genes determine one’s shape, similar to stature and hair color.
What did Astwood speculate about inactivity in relation to obesity?
He considered it of dubious importance
He suggested that inactivity could be an effect of obesity rather than a cause.
What role do hormones play in fat metabolism according to Astwood?
They strongly influence fat storage, release, and combustion
Hormones like sex hormones, thyroid hormones, and insulin are key players.
What is the relationship between insulin and fat metabolism?
Insulin promotes fat deposition and synthesis
It reduces the release of fat and the conversion of food to fat.
What does Astwood suggest could cause a voracious appetite in the obese?
A minor derangement in fat metabolism
This derangement could impede fat release or combustion.
True or False: The positive-caloric-balance hypothesis claims that overeating causes obesity.
True
This hypothesis states that the brain regulates ingestive behaviors leading to excessive calorie consumption.
What is the primary defect in the positive-caloric-balance hypothesis?
In the brain’s regulation of ingestive behaviors
It suggests that people consume more calories than they expend.
According to the alternative hypothesis, where is the primary defect located?
In hormonal and metabolic processes in the body
This leads to excessive accumulation of calories as fat.
What are the side effects of the underlying metabolic defect in obesity?
Overeating and inactivity
Hunger and lethargy are seen as consequences, not causes.
What does the alternative hypothesis propose about energy intake and expenditure?
They are dependent variables
A change in one induces a compensatory change in the other.
What is the role of carbohydrates in obesity according to the alternative hypothesis?
They regulate insulin, which affects fat deposition
Refined carbohydrates are particularly implicated.
What was the lipophilia hypothesis?
The idea that a defect in fat metabolism causes obesity
It was introduced by Gustav von Bergmann in 1908.
What does ‘lipophilia’ mean?
Love of fat
It describes areas of the body that have a higher affinity for accumulating fat.
What did Gustav von Bergmann argue about energy balance?
He considered it nonsensical in explaining obesity
He believed biological factors regulate fat accumulation.
What is the significance of insulin in the context of obesity?
It plays a primary role in fattening processes
Insulin dysfunction is linked to obesity and diabetes.
What does the alternative hypothesis suggest is the ultimate cause of common obesity?
Chronic elevation of insulin due to carbohydrate intake
This includes refined carbohydrates and sugars.
What is the phenomenon of local lipophilia?
Local lipophilia refers to the tendency of certain areas of the body to accumulate fat independent of overall body fat levels.
What clinical condition is characterized by benign fat masses?
Lipomatosis.
What are lipomas?
Fatty tumors that can develop in various parts of the body.
What condition is characterized by the inability to store fat in subcutaneous tissue?
Lipodystrophy.
How does lipodystrophy manifest in patients?
Patients appear abnormally emaciated and may lose fat in specific areas, with potential localized obesity developing later.
Who were the prominent proponents of the lipophilia hypothesis?
Bergmann and Julius Bauer.
What did Julius Bauer believe regarding the regulation of fat accumulation?
He believed a biological factor regulates fat accumulation, independent of energy balance.
What did Bauer’s research suggest about the genetic component of obesity?
He found nearly 75% of his obese patients had one or both parents who were also obese, indicating a genetic component.
What role do male sex hormones play in fat distribution?
They inhibit the type of fat formation typically seen in women.
Fill in the blank: Bauer suggested that _______ enhances the deposition of glucose in adipose tissue.
insulin.
What was the fate of the lipophilia hypothesis in the post-World War II era?
It largely disappeared from the research community, particularly in English literature.
What did the animal models of obesity suggest about the cause of obesity?
They indicated that obesity might not be solely caused by overeating but rather by defects in fat metabolism.
True or False: Genetically obese mice fatten excessively regardless of their calorie intake.
True.
What was the implication of Milton Lee’s 1934 study on rats with removed pituitary glands?
They gained significantly more weight than untreated rats, indicating weight gain independent of calorie consumption.
What happens to genetically obese mice when they are starved?
They become emaciated versions of fat mice rather than lean mice.
Fill in the blank: The most dramatic animal obesity model is known as _______.
hypothalamic obesity.
What critical turning point in obesity research involved hypothalamic obesity?
It highlighted the tendency to attribute obesity solely to overeating despite evidence to the contrary.
What did Bauer suggest about the role of the nervous system in fat accumulation?
He noted that severing nerve fibers to fat tissue could increase fat deposits.
What was a significant publication by Julius Bauer related to obesity?
Constitution and Disease.
What did the discussions on the lipophilia hypothesis mainly confine to during the 1920s?
German and Austrian research communities.
What did Russell Wilder suggest regarding the delayed sense of satiety in obese persons?
It might be accounted for by a slight tendency to withdraw fat from circulation after meals.
What did researchers conclude about the relevance of animal obesity studies to human obesity?
They often rejected the relevance, attributing human obesity primarily to overeating or sedentary behavior.
What was the effect of restricting the diet of Zucker rats from birth, according to M.R.C. Greenwood?
They grew fatter by adulthood than their littermates allowed to eat freely.
Fill in the blank: Bauer believed that _______ must exist to influence fat deposition in specific regions.
a local factor.
What was a key observation made by Francis Benedict regarding obese mice during starvation?
They lost a significant amount of body fat but remained fatter than lean mice.
What was the impact of anti-German sentiments on obesity research post-World War II?
It contributed to the disappearance of the lipophilia hypothesis from mainstream research.
What is hypothalamic obesity?
A dramatic animal obesity model used in research since the 1930s, attributed to hypothalamic dysfunction
It exemplifies the tendency to link obesity to overeating despite contrary evidence.
What is the role of the hypothalamus in obesity regulation?
The hypothalamus regulates the secretion of hormones and physiological functions related to weight management
It is connected to endocrine organs and plays a crucial role in energy balance.
What discovery did a German physician make in 1840 related to obesity?
He discovered a tumor in the hypothalamus of an obese woman who gained weight rapidly
This was one of the early links between hypothalamic tumors and morbid obesity.
Who resolved the controversy regarding the role of the hypothalamus and pituitary gland in weight regulation?
Stephen Ranson and his graduate student Albert Hetherington in 1939
They demonstrated that the hypothalamus, specifically the ventromedial hypothalamus, regulates adiposity.
What is hyperphagia?
An extraordinary hunger leading to overeating, coined by John Brobeck
It is described as a perverted appetite that contributes to obesity.
What was Ranson’s argument against Brobeck’s hyperphagia hypothesis?
Ranson argued that hyperphagia might be a symptom rather than the primary cause of obesity
He suggested a more complex interplay between energy intake and expenditure.
What is ‘hidden cellular semistarvation’ according to Ranson?
A condition where nutrients are diverted to fat tissue, leading to a lack of fuel for other cells
This results in voracious hunger and compensatory behaviors.
What happens when the ventromedial hypothalamus is damaged?
It can induce tremendous hunger and obesity due to disrupted homeostasis
This results in the body accumulating fat while experiencing constant hunger.
How did the focus of obesity research shift in the 1960s?
Research became dominated by psychological perspectives rather than physiological ones
This led to a view of overeating as a psychological issue rather than a physiological dysfunction.
What did Chandler Brooks find regarding VMH lesions in 1946?
Mice with VMH lesions became significantly obese, gaining weight per calorie consumed
This indicated that calorie utilization, not just intake, determines obesity.
What symptoms are associated with diabetes insipidus?
Excessive urination and constant thirst due to hypothalamic lesions
It involves a failure to conserve water, unlike diabetes mellitus.
What impact did Ranson’s death have on obesity research?
It shifted the authority in obesity research to Brobeck, who emphasized overeating
This led to a long-lasting focus on hyperphagia as a primary cause of obesity.
What did Ranson’s research on fluid balance contribute to understanding obesity?
It informed the interpretation of energy balance and metabolism regulation
His insights were crucial in understanding how homeostasis affects obesity.
What did Brobeck and Anand discover about the lateral hypothalamus?
Lesioning it caused rats to stop eating and lose weight
This led to the idea that it functions as a ‘feeding center’.
Fill in the blank: Damage to the _______ hypothalamus can lead to obesity.
ventromedial
True or False: The ventromedial hypothalamus is responsible for regulating hunger and ingestive behavior.
False
It is more accurately described as regulating fat metabolism, not directly hunger.
What was the misconception regarding hunger and obesity in the context of hypothalamic lesions?
That hunger caused obesity rather than being a symptom of underlying metabolic dysfunction
This misunderstanding simplified the complex physiology involved.
What happens to animals subjected to severe and permanent food restriction?
They lose some weight but do not lose the drive to fatten or the accompanying hunger.
What occurs after periods of fasting according to Brooks?
Periods of fasting are followed by an augmentation of appetite and greater obesity than before fasting.
What changes occur in animals with VMH lesions?
Changes in reproductive cycles, nocturnal eating patterns, and increased sleep duration.
What is the relationship between hibernating ground squirrels and food intake?
They double their body weight in preparation for hibernation regardless of food intake.
What did researchers find regarding dietary models of obesity in rats?
Certain strains grow obese on high-fat or high-sugar diets without increasing calorie consumption.
How does calorie intake relate to weight recovery after fasting?
Recovery of body weight is not connected to the amount of food eaten during recovery.
What occurs when ovaries are removed from female rats?
The rats eat voraciously, decrease physical activity, and quickly grow obese.
What happens when estrogen is infused back into ovariectomized rats?
They lose excess weight and return to normal eating and activity patterns.
What is the critical point about food intake and obesity in ovariectomized rats?
Obesity can occur without overeating; calorie intake does not significantly affect weight gain.
What is the link between fat accumulation and reproduction?
Fat accumulation, energy balance, and reproduction are all regulated by the hypothalamus.
What did Charles Darwin observe about food availability and reproduction?
Hard living retards the period at which animals conceive.
What is Claude Bernard’s harmonic-ensemble perspective of homeostasis?
It emphasizes the entire organism and the homeostatic web of hormonal regulation.
How did World War II affect obesity research?
It led to the suspension of obesity research for most of a decade in the United States.
What was Louis Newburgh’s hypothesis regarding obesity?
He promoted the perverted-appetite hypothesis, suggesting obesity is caused by overeating.
What did the first obesity textbook published after the war assert?
It claimed that obesity is caused by overeating, dismissing contrary suggestions as excuses.
What did Brobeck’s experiment with lesioned rats demonstrate?
Lesioned rats gained weight more rapidly than controls even when fed the same amount of food.
Fill-in-the-blank: The decoupling of _______ from weight gain was demonstrated in animal hibernation studies.
food intake
True or False: The homeostatic hypothesis of obesity in humans has been widely accepted since the mid-20th century.
False
