Understanding Which Things Are Included in Fat: A Complete Guide

December 18, 2025 •

4 min read

A single gram of fat provides 9 calories, more than double the energy of protein or carbohydrates, which have only 4 calories per gram. Understanding which things are included in fat is therefore crucial for managing your overall energy intake and promoting better long-term health.

Quick Summary

This guide breaks down the different types of dietary fat—saturated, unsaturated, and trans fats. It details their common food sources, chemical structures, and distinct effects on the body.

Key Points

Fat is essential: It is a vital macronutrient for energy storage, vitamin absorption, and cell function, not just a source of calories.
Four main fat types: Dietary fat is categorized into saturated, monounsaturated, polyunsaturated, and trans fats, each with a different chemical structure and health effect.
Unsaturated fats are healthier: Found in sources like olive oil, avocados, nuts, and fish, these fats can help lower bad cholesterol and improve heart health.
Limit saturated fat: Saturated fats, from animal products and some tropical oils, can raise LDL cholesterol and should be consumed in moderation.
Avoid trans fats: Industrially produced trans fats, found in many processed and fried foods, have no health benefits and should be avoided entirely due to increased disease risk.
Source matters: The specific food item determines the type of fat it contains; for example, while meat and dairy contain saturated fat, fish and seeds provide healthy unsaturated fats.

The Scientific Definition and Biological Function of Fat

In biological and nutritional terms, fats are a type of lipid, which are organic compounds that are insoluble in water. They are a critical macronutrient, performing several vital functions within the human body. Fats are made up of building blocks called fatty acids and are most commonly found in the form of triglycerides, a structure composed of a glycerol backbone attached to three fatty acid molecules.

Beyond providing a dense source of energy, fats are essential for the body to absorb fat-soluble vitamins (A, D, E, and K). They help build and maintain healthy cell membranes, insulate the body to regulate temperature, and protect organs from shock. The human body can synthesize most of the fats it needs, but it requires certain essential fatty acids, such as omega-3 and omega-6, which must be obtained through diet.

The Four Main Types of Dietary Fat

Not all fats are created equal, and their chemical structure dictates their physical properties and biological effects. Dietary fats can be categorized into four main types: saturated, unsaturated (which includes monounsaturated and polyunsaturated), and trans fats.

Saturated Fats

Saturated fatty acids are molecules that are 'saturated' with hydrogen atoms, meaning they lack double bonds between the carbon atoms in their structure. This makes them straight and able to pack tightly together, which is why they are typically solid at room temperature.

Common Sources of Saturated Fat:

Fatty cuts of meat (e.g., beef, lamb, pork)
Poultry with skin
High-fat dairy products (e.g., butter, cheese, cream, ice cream)
Tropical oils (e.g., coconut oil, palm oil)
Lard and ghee

Unsaturated Fats

Unsaturated fats contain one or more double bonds in their fatty acid chains, which puts a bend in the molecule, preventing them from packing tightly together. This is why they are usually liquid at room temperature and are generally considered healthier for heart health.

Monounsaturated Fats

These fats have only one double bond in their structure. They have been shown to help lower LDL ('bad') cholesterol levels while maintaining HDL ('good') cholesterol.

Common Sources of Monounsaturated Fat:

Olive oil and canola oil
Avocados
Nuts (e.g., almonds, pecans, peanuts)
Sesame seeds and pumpkin seeds

Polyunsaturated Fats

These fats have two or more double bonds. They also help reduce LDL cholesterol and provide essential omega-3 and omega-6 fatty acids that the body cannot produce on its own.

Common Sources of Polyunsaturated Fat:

Oily fish (e.g., salmon, mackerel, tuna)
Walnuts
Seeds (e.g., flaxseeds, chia seeds)
Vegetable oils (e.g., sunflower oil, corn oil, soybean oil)

Trans Fats

Trans fats, or trans-fatty acids, are a form of unsaturated fat that has a chemical structure similar to saturated fat due to the positioning of hydrogen atoms. While a small amount occurs naturally in the meat and dairy of ruminant animals, most trans fat is industrially produced through a process called partial hydrogenation. Industrially produced trans fats are associated with increased heart disease risk and have no known health benefits. Due to their health risks, many countries have limited or banned their use.

Common Sources of Trans Fat:

Commercially baked goods and snacks
Some stick margarines and vegetable shortenings
Fried foods from fast-food restaurants
Processed foods containing partially hydrogenated oil

Which Things Are Included in Fat: A Comparison


Feature	Saturated Fat	Unsaturated Fat	Trans Fat
Physical State (Room Temp)	Solid	Liquid	Solid (Artificially)
Primary Sources	Animal products (meat, dairy), tropical oils	Plant-based sources (oils, nuts, seeds), fish	Industrially processed foods, some animal products
Chemical Structure	No double bonds, straight fatty acid chains	One or more double bonds, bent fatty acid chains	Unsaturated fats with hydrogenated properties
Health Impact	Can raise LDL cholesterol; limit intake	Can lower LDL cholesterol; beneficial for heart health	Increases LDL and lowers HDL cholesterol; avoid entirely
Examples	Butter, coconut oil, cheese	Olive oil, avocado, salmon, walnuts	Margarine, fried foods, cookies

The Role of Fat in Health and Diet

Including the right types of fat in your diet is vital for maintaining good health. While healthy, unsaturated fats can improve cholesterol levels and reduce the risk of heart disease, unhealthy trans fats should be avoided, and saturated fat intake should be limited. The American Heart Association provides excellent guidance on making smart dietary fat choices. Choosing lean meats, low-fat dairy, and incorporating more plant-based and fish sources of fat are excellent ways to improve your fat intake. Cooking methods also matter; opt for grilling, baking, or steaming instead of frying, which can add unnecessary fat and calories.

Conclusion

Understanding which things are included in fat goes beyond simply categorizing foods; it's about recognizing the critical differences in fat types and their impact on our health. By replacing unhealthy saturated and trans fats with beneficial unsaturated fats from plant sources and fish, you can make a significant positive change to your diet and overall well-being. A balanced intake of healthy fats is not a recommendation to fear all fat, but rather an invitation to make informed and mindful dietary choices for a healthier life.

Frequently Asked Questions

Saturated fats lack double bonds in their chemical structure and are typically solid at room temperature. Unsaturated fats contain at least one double bond and are generally liquid at room temperature.

Unsaturated fats, including monounsaturated and polyunsaturated fats, are considered the healthiest. They are primarily found in plant-based oils, nuts, seeds, and fish.

Most trans fats are industrially produced and found in processed foods like certain baked goods, fried foods, and some margarines. They are often listed on ingredient labels as "partially hydrogenated oil".

The body needs fat for various functions, including energy production, absorbing fat-soluble vitamins (A, D, E, K), insulating organs, and maintaining cell health.

No, while animal fats tend to be higher in saturated fat, some, like pork and poultry, also contain significant amounts of unsaturated fats. The fats in fish, for example, are predominantly unsaturated.

Essential fatty acids are polyunsaturated fats, like omega-3 and omega-6, that the human body needs for proper function but cannot produce on its own. They must be obtained through the diet.

While coconut oil is a plant-based fat, it is very high in saturated fat and can increase LDL cholesterol levels. For better heart health, it is generally recommended to use unsaturated fats like olive or canola oil.