Nutrition And Diet

Nutrition is the science that studies how food affects the body, including the processes of ingestion, digestion, absorption, and utilization of nutrients for growth, maintenance, and repair.
It involves macronutrients, micronutrients, and water to support health.

Macronutrients are nutrients required in large amounts, including carbohydrates, proteins, and fats, which provide energy and building blocks for the body.
They are measured in grams and supply calories: 4 kcal/g for carbs and proteins, 9 kcal/g for fats.

Carbohydrates are the body's main energy source, providing 4 kcal per gram, and are essential for brain function and physical activity.
They are broken down into glucose for immediate use or stored as glycogen in the liver and muscles.

Proteins are made of amino acids, of which there are 20 types, including 9 essential ones that must come from diet.
They build and repair tissues, produce enzymes and hormones, and provide 4 kcal per gram.

Dietary fats include saturated, unsaturated (monounsaturated and polyunsaturated), and trans fats.
Unsaturated fats, like those in olive oil and fish, support heart health, while saturated and trans fats should be limited.

Micronutrients are vitamins and minerals needed in small amounts for metabolic processes, immune function, and bone health.
They do not provide calories but prevent deficiencies like scurvy or rickets.

Water is essential for digestion, nutrient transport, temperature regulation, and waste elimination, comprising 60% of body weight.
Daily needs vary but average 2-3 liters from fluids and food.

A calorie is a unit of energy, specifically the amount needed to raise 1 gram of water by 1°C; dietary Calories (kcal) measure food energy.
Daily intake depends on age, sex, activity, averaging 2000-2500 kcal for adults.

The main food groups are fruits, vegetables, grains, proteins, and dairy, as per MyPlate guidelines.
Half the plate should be fruits and vegetables, with whole grains and lean proteins filling the rest.

RDA (Recommended Dietary Allowance) is the average daily nutrient intake level sufficient for 97-98% of healthy individuals.
It guides dietary planning to prevent deficiencies.

BMI (Body Mass Index) estimates body fat using weight in kg divided by height in meters squared (kg/m²).
Categories: under 18.5 (underweight), 18.5-24.9 (normal), 25-29.9 (overweight), 30+ (obese).

Dietary fiber is indigestible plant material that promotes digestive health, lowers cholesterol, and stabilizes blood sugar.
Aim for 25-38g daily from fruits, vegetables, and whole grains.