Chapter 8: Energy Balance & Body Weight Reduction

When does energy balance occur?

when energy intake = energy expenditure

Positive energy balance

occurs when energy intake > energy expenditure

Negative energy balance

occurs when energy expenditure > energy intake

An example of a hormone produced by adipose tissue is ____.

adipokines

Adipokines

hormones released by adipose tissue that allow for communication between fat cells

The primary function of adipokines is to:

regulate immune and inflammatory responses

What are the two types of adipose tissue?

• visceral adipose tissue (VAT): essential fat surrounding organs

• subcutaneous adipose tissue (SCAT): fat under the skin

Adipose tissue can experience ___ or ___ growth.

hypertropic or hyperplastic

Hypertropic Growth

occurs when the size of adipocytes increase (S —> L)

Hyperplastic Growth

occurs when the number of adipocytes increases (1 —> 2)

What happens to adipocytes during weight loss?

they decrease in size

What determines energy intake?

• hunger

• appetite

• satiety

Hunger

the physiological drive to consume food

Appetite

the desire to eat a particular food (ex: hamburger)

Satiety

the feeling of fullness

Hunger, satiey, and appetite are all products of ____ between the gut and the brain.

neural connections

Regarding energy intake, the hypothalamus regulates ___ and ___.

hunger and satiety

______ neurotransmitters released by the hypothalamus promote satiety.

Catabolic

_____ neurotransmitters released by the hypothalamus promote hunger.

Anabolic

What three things regulate short-term food intake?

• gastric stretching

• circulating nutrient levels

• gastrointestinal hormones

Gastric stretching

as the stomach fills with food, stretch receptors in the stomach relay info to the brain via neural signals to inhibit further food intake

Circulating nutrient levels

• when nutrient (glucose, AA, FAs) concentrations are high in the bloodstream they can signal satiety

• when nutrient concentrations are low in the bloodstream they can signal hunger

GI hormones

GI hormones are released in the presence or absence of food to regulate food intake (ex: ghrelin stimulates food intake)

Bariatric Surgery

A medical procedure that helps those with obesity lose weight by modifying the digestive system

Types of bariatric surgery

• gastric banding

• gastric sleeve

• gastric bypass

Gastric banding surgery

reduces the size of the stomach by wrapping an adjustable band around the upper portion of the stomach. This creates a small stomach pouch that fills quickly with food, triggering satiety

Gastric bypass surgery

reduces the size of the stomach and bypasses a segment of the small intestine. This procedure helps people eat less food and also decreases nutrient absorption

Gastric sleeve surgery

removes a large portion of the stomach, creating a tube-like structure. This limits food intake and results in hormonal changes that help with weight loss.

Name 4 GI hormones?

• CCK

• Glucagon-like peptide 1 (GLP-1)

• ghrelin

• peptide YY

What effect does CCK, GLP-1s, and peptide YY have on food intake?

they decrease food intake

Ghrelin ___ food intake.

increase

What are examples of GLP-1 medications?

• Mounjaro

• Wegovy

• Ozempic

• Zepbound

True or False: GLP-1s alone can’t treat Type II diabetes or obesity.

True, GLP-1 medications need to be combined with lifestyle and dietary changes to effectively lose weight and manage diabetes

How do GLP-1 medications work?

GLP-1 medications mimic actual GLP-1 hormones and bind to their receptors. They then trigger the effects of the hormone.

Effects of GLP-1 medications:

• triggers insulin release

• blocks glucagon secretions

• slows gastric emptying

• increases feelings of satiety

GLP-1 agonists are generally safe. But there are a few risks to consider when taking them. What are those risks?

• allergic reactions

• hypoglycemia (low blood sugar)

• GI issues

• muscle loss

Total energy expenditure (TEE)

the total amount of energy used by the body

Total energy expenditure (or caloric use) is measured by:

• basal metabolism

• physical activity

• thermic effect of food

Basal metabolism

the energy required to perform for basic life functions (accounts for 50-70% of TEE)

Physical activity

the energy required to move (accounts for 15-30% of TEE)

Thermic effect of food

the energy required to process food (accounts for 10% of TEE)