Nutrition, Metabolism, & Energy Balance

nutrients

Substances in food needed for growth, maintenance, and/or repair

Macronutrient

nutrients which are consumed in relatively large quantities

Micronutrient

nutrients which are consumed in relatively small quantities

Essential Nutrient

nutrients which our body cannot synthesize itself or in enough quantity to keep up with demand

metabolism

Sum of the biological chemical reactions in the body

Anabolism

reactions that build (synthesize) larger molecules/structures from smaller ones

Catabolism

reactions that break down complex structures into simpler ones

Energy is measured as

kilocalorie

Positive Balance

Energy Intake > Energy Use (Anabolic state)

Negative Balance

Energy Intake < Energy Use (Catabolic state)

Zero Balance

Energy Intake = Energy Use

Carbohydrates

Made up from “sugar” molecules

Monosaccharides

1 “sugar” group – Glucose, Fructose, Galactose

Disaccharides

2 “sugar” groups – Sucrose, Maltose, Lactose

Polysaccharides

have multiple “sugar” groups

All “sugars” broken down & converted into

glucose

Recommended 45 – 65% total daily calories

carbohydrates

nsoluble Fiber (Cellulose)

will not dissolve in water; cannot be digested in humans

Soluble Fiber

will dissolve in water & can be digested in humans

Glycolysis

Breakdown of a single glucose into Pyruvate (aerobic) and Lactate (anaerobic)

Krebs (Citric Acid) Cycle

Pyruvate gets converted into Acetyl-CoA

Electron Transport Chain (Oxidative Phosphorylation)

Transport of hydrogens across membrane stimulates ATP synthase converting ADP → ATP

Lipids

• Fuel, organ protection, insulation (adipose tissue)
• Cell membrane structure (phospholipids & cholesterol)
• Steroid hormone production & function (cholesterol)
• Vitamin absorption
• Makes food tasty

Lipids are made from

chains of fatty acids bound with a glycerol group

Triglycerides (TGs)

most abundantly consumed form

Saturated Fats

found in most animal byproducts

Unsaturated Fats

found in most plant products

Recommended not to exceed 35% of total daily calories

Lipids

Lipolysis

Enzyme lipase splits TG into glycerol and component fatty acids

Beta-oxidation

Fatty acids get broken down into components at every second carbon group

Protein

• Tissue structures
• Enzyme & hormone production & function
• Fuel (if all others have been depleted)

Complete Protein

contain all 9 essential amino acids

Incomplete Proteins

missing some essential amino acids

There is no such thing as too much

protein

Deamination

amine (NH2) group is removed yielding Pyruvate OR Krebs intermediate components & ammonia (NH3)

Vitamins and Minerals

Do not contribute to energy supply

Vitamins

organic compounds which needed in the diet

Vitamins that can be synthesize

Vitamine D, K, B

Fat solube vitamins

Vit. A, D, E, & K

Minerals

inorganic compounds found in nature