human nutrition Flashcards
Describe the role of lipoprotein lipase (LPL) in obesity development and how its activity differs between obese and lean individuals.
LPL plays a major role in lipid metabolism and storage. Obese individuals generally have higher LPL activity in adipose cells, making fat storage more efficient. Modest excesses in energy intake have a more dramatic impact on obese people than on lean individuals.
How does gender influence the activity of LPL in different regions of the body, and what is the significance of these differences?
Gender influences LPL activity, with women having abundant LPL in the breasts, hips, and thighs, leading to pear-shaped fat distribution. Men, on the other hand, have abundant LPL in the abdomen, resulting in apple-shaped fat distribution.
. Explain the Set-Point Theory and how it relates to weight regulation.
The Set-Point Theory suggests that the body has a fixed weight point, and after weight loss, the body adjusts its metabolism to favor weight regain. This adaptation can make it difficult for individuals to maintain weight losses.
Why is the decrease in metabolic rate after weight loss greater than expected based on body composition alone?
The decrease in metabolic rate after weight loss is greater than expected, suggesting the body adapts to favor weight regain. This phenomenon helps explain the challenges of maintaining weight losses.
Why do people accumulate excess body fat, according to the information provided in Chapter 9.2?
People accumulate excess body fat when they intake more energy from foods and beverages than they expend in physical activity and metabolic processes. The section highlights the interplay of various factors, including genetics, environment, culture, behavior, socioeconomic status, and psychology.
How does genetics contribute to obesity, and what is the role of epigenetics in this context?
pigenetics, influenced by environmental factors like diet and physical activity, regulates gene expression. Studies on adopted children and twins suggest a significant genetic component in determining susceptibility to obesity. Epigenetic changes accumulate over time, emphasizing the impact of lifestyle on genetic factors.
. Describe the role of the protein leptin in appetite control and energy regulation. How does leptin influence body weight and fatness?
Leptin, produced by the obesity gene (ob) in adipose tissue, acts as a hormone in the hypothalamus. It regulates food intake and energy expenditure. Leptin increases with body fat, suppressing appetite, and decreases with reduced body fat, stimulating appetite. Mice with a defective ob gene, lacking leptin, exhibit massive obesity, and injecting leptin leads to weight loss. Leptin deficiency in humans is rare, but decreased sensitivity (leptin resistance) is associated with obesity.
Explain the role of ghrelin in appetite regulation and its response to different meal-related factors.
Ghrelin, secreted by stomach cells, promotes a positive energy balance and increases body weight and fatness by stimulating appetite. Ghrelin levels rise before meals and decline afterward. Factors like mindset influence ghrelin’s response to meals. Research suggests that perceptions of indulgence or sensibility affect ghrelin response, impacting satiety.
How do uncoupling proteins, such as those in brown adipose tissue, influence energy metabolism and body weight regulation?
Uncoupling proteins in brown adipose tissue release energy as heat instead of storing it, defending against cold and preventing obesity. Brown fat activity declines with age and obesity. White fat cells can undergo browning, converting into brite adipocytes with uncoupled proteins. Physical activity and GI microbiota influence browning, offering potential avenues for obesity treatment.
What is an “obesogenic environment,” and how does it contribute to the rising rates of obesity?
An obesogenic environment includes daily circumstances pushing individuals toward fatness. Over the years, reduced demand for physical activity coupled with the abundance of readily available, energy-dense foods has challenged the body’s ability to defend against weight gains. Genetic and environmental factors interact, creating epigenetic effects that contribute to obesity and related diseases.
How does overeating, particularly in an environment of large portion sizes, contribute to obesity?
Overeating, especially with the prevalence of large portion sizes and ready-to-go combo-meals, leads to increased energy intake. The trend toward larger portions parallels the rise in obesity rates. Reduction in portion sizes and consumption of low-energy-density foods like fruits and vegetables can aid in weight management.
In what ways does physical inactivity contribute to weight gain, and how has modern technology affected physical activity levels?
Physical inactivity, fueled by modern technology replacing exertion in daily life, contributes to weight gain and poor health. Sedentary activities like watching TV and using computers reduce energy expenditure and influence food choices, leading to weight gain. Recommendations emphasize the importance of physical activity in preventing weight gain and maintaining nutritional health.
Explain the concept of nonexercise activity thermogenesis (NEAT) and its role in energy balance and weight management.
Nonexercise activity thermogenesis (NEAT) involves energy expenditure in daily spontaneous activities. Lean individuals tend to be more spontaneously active in their occupations and leisure time. Differences in time spent lying, sitting, standing, and moving can account for about 350 kcalories a day, playing a pivotal role in energy balance and weight management.
Why is it mentioned that “millions of US adults are trying to lose weight on any given day”?
The introduction implies a widespread concern about weight loss among adults in the United States.
According to Chapter 8, how do health-care professionals assess the potential health risks of obesity?
Health-care professionals use BMI and waist circumference to determine the potential health risks of obesity.
