A nutrient is a component in food that the organism uses to survive and grow. Macronutrients are types of food or chemical elements that humans consume in everyday life. There are three primary macronutrients: car protein, carbohydrates, and fats (or protein, carbs, and fats). Each of them has their nutritional value. There are also more macronutrients that has nutritional value like alcohol and those that don’t provide nutritional value like water, fiber, micronutrients.

PROTEIN, CARBS AND FATS OVERVIEW

PROTEIN

Proteins are one of the building blocks of body tissue but they can also serve as a fuel source. They provide 4 kcal per gram of energy. Proteins are made up of amino acids that are stored in cells and bound with enzymes. There is a limited amount of proteins (amino acids) that the body can take so the excess is dissolved as an energy source or stored as fat.

There are essential amino acids and non-essential amino acids. There are 9 amino acids our body needs but cannot produce for itself so it must be obtained through food while there are 11 non-essential amino acids that can be produced by our own body.

FATS

Fats are composed of three fatty acid chains thus they are called triglycerides. Fats are broken down into glycerol and fatty acids. Glycerol can be converted to glucose and become a source of energy. Metabolized fat releases 9 kcal per gram. There is unsaturated and saturated fat.

UNSATURATED FAT	SATURATED FAT
Monounsaturated fat Polyunsaturated fat (essential fats omega 3 and omega 6) Trans fat	Interesterified fat

Fats are an important part of any diet because some vitamins like A,D,E,K are not absorbed if they are not bound to fat.

CARBOHYDRATES

Carbohydrates are a common source of energy but no carbohydrate is an essential nutrient in humans. Carbs produce 4 kcal of energy per gram.

Monosaccharides are the simplest carbohydrates that cannot be broken down into smaller carbohydrates. They are the major source of fuel for metabolism. Glucose is the most important simple sugar in the human body and only fuel brain can use beside ketone bodies. Besides sugars, the human body needs non-starch polysaccharides knows as fiber. They cannot be metabolized or absorbed by humans but with their volume, they speed up the process of elimination and prevent constipation.

Unused glucose is metabolized in the liver in glycogen. As glycogen, it can be stored in the liver and muscles. But there is limited capacity. The liver can store about 100g of glycogen and muscles around 500g, the rest is stored as adipose tissue (fat). 

Sugars	Polysaccharides
MONOSACCHARIDES	DISACCHARIDES	STARCH	NON-STARCH
Glucose Galactose Fructose Xylose	Sucrose Lactose Maltose Trehalose	Amylose Amylopectin	Cellulose Hemicellulose

ALCOHOL

Alcohol is also a nutrient that yields energy. One gram of alcohol produces 7 kcal of energy. The human body produces around 3 grams of ethanol per day merely through fermentation.

PROTEIN, CARBS, AND FATS RATIO IN DIET

Which amount of protein, carbs, and fats you will be consuming, depends on your diet goals and your body type. It is wrong to cut down carb or fats, considering them bad for your health or weight loss goals. The key is in the right ration of these macronutrients.

If you go for a keto diet, you will set your daily meal plan to contain 5 % of carbs, 25 % of proteins.

For a low carb diet, the recommended macro percentages are 30 % of proteins, 15 % of carbs and 55 % of fats.

It is a common rule that if you go low on carbs, you should replace energy needs from fats and proteins. It is the worst idea to choose a low carb and low-fat diet. It is a recipe for a catastrophe because you will be starving all day. Because of that, we are constantly making new meal plans that help you to lose weight without starving.