Weight Regulation and Genetics

Flashcards on weight regulation, genetics in weight regulation, and related topics.

Dipostatic Body Weight Regulation

Your body tries to essentially defend a certain body weight.

Ideal Dipostatic Signal

A signal that tells the brain how much fat the body contains.

Leptin

A hormone produced by fat cells with receptors in the brain.

Adopted Children Studies

Studies comparing body weight of adopted children to adoptive and biological parents to distinguish environmental and genetic effects.

Twin Studies

Studies comparing body weights of identical and fraternal twins raised together or apart.

Heritability of Body Mass Index

Somewhere between a half to two thirds of your body mass index is actually due to your genes rather than your environment.

Monogenic Syndromes

Defects in a single gene that can lead to obesity.

Susceptibility Genes

Multiple genes that predispose you to becoming overweight depending on the environment that you're in.

Pima Native Americans

A case study demonstrating interactions between environment and susceptibility to obesity.

Arizona Pima

Pima who live a modern lifestyle and have high rates of obesity and type 2 diabetes.

Mexico Pima

Pima who live a traditional lifestyle and have low rates of obesity and type 2 diabetes.

Thrifty Phenotype

A genotype that allows individuals to extract nutrients from foods more efficiently and expend less Energy.

Set Point Hypothesis

The idea that your body likes to keep a particular amount of fat at a stable amount.

Counter Regulations

The body kicks in counter regulations that tries to get you back to that level that it expects you to be at.

Liposuction

Doesn't work because people put the weight back on in other places .

Ideal Properties of Feedback Signal

Hormone secreted from fat cells, secreted in proportion to fat stores, crosses the blood-brain barrier, brain receptors exist, and has same impact when injected.

Negative Feedback Loops

The presence of something inhibits a particular pathway.

OB Mouse

Mutant mouse strain used to discover hormone leptin.

Leptin Discovery

Made by joining the circulation of a normal mouse to a fat mouse with a lesion in the hypothalamus and found that the normal mouse got skinny.

DB Gene

Encodes for a receptor for a appetite signal.

OB Gene

Encodes for a particular negative feedback hormone.

Plasma Levels of OB Protein

Should increase in obese animals and decrease with weight loss signalling how much fat the animal actually has.

Leptin and Adipocytes

Fat cells were producing this hormone leptin.

OB gene expression

Expressed in adipose tissue, it encodes the hormone leptin

Leptin and weight loss

Mice that received a higher dose leptin actually lost more weight.

Leptin and Body Temperature

Leptin restores the body temperature in those OB mice.

Leptin and Oxygen Consumption

If you treat mice with that OG mutation with leptin, then their metabolic rate, their oxygen consumption comes back to a similar level as normal mice.

Neuropeptide Y

It both stimulates food intake and suppresses energy expenditure, and if you administer it to the hypothalamus in rats, then it actually leads to obese rats

Leptin and Neuropeptide Y

Leptin and neuropeptide Y interact to influence food intake and energy expenditure.

Feedback Cycle (Adipose Tissue to Hypothalamus)

reduces food intake, increases metabolism, and increases energy expenditure, and that in turn, together reduces the amount of fat that is in your adipose tissue, which will then reduce the amount of leptin circulating in your blood.

Leptin Deficiency

Leads to weight gain.

Leptin usage

Didn't solve everything because we do still have problems with, people being overweight and obese.

Type 2 diabetes and leptin

People become resistant to leptin, kind of in the same way that people with type two diabetes become resistant to insulin.

Leptin entry into bloodbrain barrier.

Human obesity is likely at least partially linked to insensitivity to leptin.

Leptin levels

Seem to plateau in obese humans even when there is a lot of leptin circulating in the plasma.

Weight loss

Results in a drop in plasma leptin, and then that stimulates you to regain weight, which is why diets often fail, especially if you try to lose weight quickly.

Obesity development

Develops in lots of different ways.

Monogenic Obesity

Specific aberrant gene that results in a particular phenotype.

Polygenic Obesity

Multiple variant genes, and then if you've got different combinations of those leads to different levels of disease.

Environmental factors

Polygenic obesity is particularly important.