Energy Balance Flashcards
Define respiratory quotient and name the quotients for carbs, protein, and fat.
vC02/v02
- 0 - carbs
- 85 - protein
- 7 - fat
What are the three components of total energy expenditure (TEE)? What are their relative proportions of TEE?
- Basal energy expenditure (BEE) - 60-70%
- Thermic effect on feeding (TEF) - 10-15%
- Physical activity (EEPA) - 30-40%
What is the major tissue determinant of basal energy expenditure (BEE)?
Fat free mass (FFM) aka lean mass
Stimulation of the ____ _______ receptor can lead to the activation of uncoupling protein to increase heat production in adipose cells.
beta-3 adrenergic
What is the primary hormonal determinant of BEE?
Thyroid hormone
BEE drops ____% per year as a result of aging.
1-2%
Foods rich in which macronutrient result in the highest thermic effect of feeding (TEF)?
Protein
What are the two components of energy expenditure for physical activity (EEPA)?
- Expenditure during exercise and excess post-exercise oxygen consumption (EPOC).
- Non-exercise activity thermogenesis
Basal energy expenditure can better adapt to ______feeding than to ______feeding.
Adapts better to underfeeding than to overfeeding.
What is the non-homeostatic food intake mechanism?
The reward system
Do leptin and insulin control long-term, or short-term food intake?
Long-term
What nutrients do enteroendocrine cells detect and what do they send their signals through?
Detect carbs, amino acids, LCFAs and SCFAs. “Gut hormones” are sent to vagal neurons, spinal neurons, enteric neurons, and into fenestrated capillaries –> circulation.
Is Ghrelin a peptide or steroid hormone?
Peptide
Where is Ghrelin produced?
Stomach
On what organ does Ghrelin act on?
Hypothalamus
What does Ghrelin do?
Make you hungry
People that are obese have _____ levels of ghrelin than people who are of normal weight.
Lower
What hormone is thought to mediate the satiety gained through high protein diets?
CCK
Can a very high protein diet increase risk for bone loss?
Yeah
Where is CCK secreted from? In response to what?
Duodenum in response to protein and fat.
What gastric effects result from CCK secretion?
Satiation and delayed gastric emptying
What does CCK act on?
Vagus nerve
How do high glycemic index foods result in more frequent eating?
The spike in insulin may actually cause hypoglycemia –> hunger
Is there evidence to support long-term weight loss as a result of low glycemic index diets?
No
Name three things that fiber does in the GI tract.
- Delays emptying
- Promotes stretch
- Decreases the rates of absorption and digestion
Name a benefit of delaying food digestion and absorption.
As food moves distally in GI tract, enteroendocrine cells become more frequent and they will secrete more GLP-1 and peptide YY (hormones)
Where is GLP-1 made and what triggers its secretion?
Made by L cells in the small intestine in response to luminal macronutrient sensing and vagal input.
What are the actions of GLP-1?
Delayed gastric emptying, incretin effect (glucose-dependent insulin secretion)
Where is peptide YY made and what triggers its secretion?
Made by L cells in the distal small intestine and in the colon in response to luminal macronutrients.
What are the effects of peptide YY?
Delayed gastric emptying, satiety.
What three things affect the energy density of a food?
water, fat, fiber
Which cells make leptin? What organ does it act on?
Adipose. Acts on hypothalamus.
What does leptin do? Is its secretion proportional to fat stores?
Leptin is a satiety hormone. It is proportional to fat stores but people who are obese are less sensitive to the hormone.
Non-homeostatic control (reward) is mediated by the ______ ______. Can it override homeostatic controls?
Limbic system. Can override homeostatic controls.
What is the most common medical cause of obesity?
Polygenic
How is leptin deficiency treated?
With leptin
What is the melanocortin 4 receptor? What happens if it is mutated?
It is an MSH receptor somehow involved in the leptin signaling pathway. If mutated –> obesity; also associated with binge eating.
What is ectopic fat distribution?
Accumulation of fat in organs
What do FFAs and inflammatory cytokines from excess adipose do to insulin signaling?
They inhibit the GLUT4 receptor response.
At what BMIs are weight loss medications indicated?
30 or greater or 27 or greater with comorbidities.
When is weight loss surgery indicated?
40 or greater BMI (or 35 and up with comorbidities), less invasive treatments have failed, desired by patient.
