Quiz 10: Biomedical Sciences (Shier)

What makes obesity so hard to treat?

obesity doesn't respond well to most treatments because the causes are mixed and not fully understood as genetics, metabolism, environment, poverty, and food availability all play a role.

Why does poverty worsen obesity rates?

because cheap foods tend to be carb-heavy and low in protein, which drives overeating and weight gain

How do you calculate BMI?

BMI = weight (kg) / height (m²)

- doesn't tell you where the fat is or how metabolically unhealthy a person is

What is one major limitation of BMI?

BMI treats all fat as the same, but visceral fat is dangerous, and subcutaneous fat can be neutral or even protective. BMI can miss this difference.

How does waist-hip ratio improve on BMI?

WHR looks at fat distribution, especially abdominal fat, which better predicts heart risk

When did the U.S. obesity epidemic begin, and what does the trend look like?

began around 1975 and kept rising until around 2020, when rates may have plateaued

What does "mortality vs BMI is U-shaped" mean?

People with very low or very high BMI have increased mortality. Mortality is lowest near the middle, and the curve flattens after age ~70

What type of fat is most strongly linked to cardiovascular risk?

Visceral fat = high CV risk

Subcutaneous fat = neutral or maybe even a little protective

Why is white adipose tissue considered an endocrine organ?

they release hormones and cytokines, including some that are inflammatory

- adipose tissue communicates with the brain, liver, pancreas, and immune system

What is the "obesity paradox"?

some studies show that people with "overweight" BMI have lower mortality in certain diseases

What are obesogenic drugs?

Medications that cause weight gain without increasing appetite.

ex. insulin, psych drugs

- can cause weight gain >5 kg/year

What is one possible cause of the obesity epidemic?

No single cause is proven. A leading theory (not proven) is an environmental obesogen; a chemical in food packaging or environment promoting weight gain

How much weight does the average adult gain per year?

one pound per year throughout adulthood; slow, steady gain that adds up over decades

What actually controls your weight long-term?

weight is controlled mainly by your hypothalamus and your brown and white adipose tissue, not by how much you consciously eat

Which eating disorder has the highest mortality rate of any mental illness?

Anorexia nervosa - higher mortality than depression. It's tied to an intense fear of gaining weight.

Which eating disorders have official DSM-5 criteria?

anorexia nervosa, bulimia nervosa, and binge-eating disorder

What is unique about orexigenic drugs in current use?

none were originally developed as appetite stimulants, weight gain was a side effect later repurposed for treatment

Why was orlistat once the only remaining weight loss drug on the market?

many previous drugs were withdrawn due to serious adverse effects, leaving orlistat as the only option for a period

Why are amphetamines only approved for short-term weight loss?

they are stimulants with cardiovascular and dependency risks → FDA limits them to ≤12 weeks

What is the mechanism of action of orlistat?

it inhibits gastric and pancreatic lipases, preventing triglyceride breakdown → undigested fat can't be absorbed

Do GLP-1 receptor agonists directly remove fat?

No, drugs like liraglutide, semaglutide, and tirzepatide support staying on a calorie-deficit diet (negative nutrient balance)

What causes most side effects of GLP-1 RAs?

not eating (fatigue, nausea, low energy) + drug mechanism (delayed gastric emptying → constipation, stenosis)

Why can GLP-1 RAs affect drug absorption?

their delayed gastric emptying (especially tirzepatide) slows absorption → can reduce effectiveness of oral contraceptives

What types of weight-loss devices act by adding stomach bulk?

hydrogel bulking agents and gastric balloons

What major metabolic benefit is associated with Roux-en-Y gastric bypass?

up to 90% reversal of type 2 diabetes, often within days

What characterizes the Mediterranean diet?

high olive oil, legumes, fruits, vegetables, high/moderate fish, moderate dairy → lower CHD risk

What characterizes the Scandinavian diet?

high meat, low vegetables, high fat intake → very high CHD incidence

Why should many fad diets be avoided?

They lack evidence or are unsafe. Atkins/low-carb diets do promote weight loss but, they come with kidney, heart, and metabolic risks

What are the clinical uses of ketogenic diets (KDs)?

- epilepsy (for drug-resistant patients)

- obesity

- type 2 diabetes (improves glycemic control)

What is metabolic syndrome?

a cluster of risks (insulin resistance, ↑TG, ↓HDL, ↑BP, ↑waist circumference) that increase risk of heart disease, stroke, diabetes

How is high fructose intake linked to metabolic disease?

drives insulin resistance, weight gain, elevated LDL/TG, and contributes to type 2 diabetes and metabolic syndrome

What cardiovascular risk is associated with erythritol and xylitol?

studies show ~2-fold increase in risk of major adverse cardiovascular events

What is MASH and why is it a concern?

Metabolic dysfunction-associated steatohepatitis → a progressive fatty liver disease similar to alcoholic hepatitis, now becoming more common due to obesity

What are the two main functions of dietary carbohydrates?

energy production and preventing ketosis from excessive fat metabolism

What spectrum do carbohydrates range across?

from simple sugars to fiber

What varies widely among different sweeteners?

sweetness level and glycemic index

Why can sugar alcohols like erythritol and xylitol be dangerous?

they may increase cardiovascular risk by enhancing platelet reactivity.

Why must carbohydrate absorption occur early in the small intestine?

to prevent flatulence from bacterial fermentation

Why do branched starches have a higher glycemic index than unbranched ones?

they are digested faster

What products help prevent lactose intolerance and how is the condition diagnosed?

Lactaid (β-galactosidase); diagnosed via hydrogen breath test or stool acidity test

What products help prevent legume-related gas?

Beano (α-galactosidase)

What is carb counting used for?

managing blood glucose in diabetes alongside insulin therapy

Besides energy, what are fats and lipids used for?

storage, insulation, emulsification, and synthesis of regulatory molecules like prostaglandins

Which fatty acids must be obtained through the diet?

omega-3 fatty acids, linoleic acid, and α-linolenic acid

Why are trans fats considered harmful?

they are now known to be more dangerous than saturated fats

What are the two main sources of cholesterol in the body?

liver synthesis (~800 mg/day) and dietary intake (300-500 mg/day)

How do plant sterol esters help lower LDL cholesterol?

they block absorption of dietary cholesterol

What are the major steps in fat digestion and absorption?

1. fat triggers CCK release

2. gallbladder contraction + sphincter relaxation

3. bile salts emulsify fat

4. pancreatic lipase breaks down triglycerides

5. small droplets absorbed with fat-soluble vitamins

6. micelles → chylomicrons

7. bile salts recycled by the liver

What do bile acid sequestrants do?

prevent bile salt reabsorption by binding them in the gut

What are symptoms of essential fatty acid deficiency?

flaky itchy skin, scalp sores, hair loss, diarrhea, stunted growth

What are major functions of proteins in the body?

structure, enzymes, hormones, transporters, immunity, buffering, osmolarity, neurotransmission, energy when needed

Which enzymes digest proteins?

pepsin, trypsin, and chymotrypsin

What causes malodorous amines in the large intestine?

decarboxylation of unabsorbed amino acids

When does protein requirement increase?

growth, infection, burns, trauma, toxicity, corticosteroid use, thyroid hormone, and insulin

How many essential amino acids must come from the diet?

nine

How can plant proteins "complement" each other?

by supplying missing amino acids; ex., beans + rice

Why is gelatin an issue for certain populations?

it comes from animal collagen, making it difficult for vegetarians, Jews, and Muslims to avoid in pharmaceuticals

What are oral nutrition products used for?

specialized nutrition in geriatrics, ICU/critical care, diabetics, pre-term infants, NICU, and other clinical populations