Physiology of Weight Loss - Why We Have Fat

Fat. Most of us have some we’re trying to get rid of, and it can affect the way we see ourselves. It’s important to remember that we as humans need fat in order to live. Developed as survival mechanism, body fat helps us when food and its energy is not immediately available. Body fat is an easy way to store energy when we have a surplus, and allows us to tap into it when there’s scarcity.

Dietary vs Body Fat

Contrary to popular belief, eating fat will not necessarily make us fat. The fat we eat is not the same as the fat we carry under our skin. The body gets energy mainly from two out of the three macronutrients, carbohydrates and dietary fats. Dietary fats are composed of fatty acids, and are essential for the body to function. Body fat is created only when there is excess energy gained by eating any of these macronutrients.

How It’s Made

Energy that the body can use is typically measured in calories. Calories are consumed in the food we eat, and are utilized both during activity and also at rest. At every point throughout the day, your body is using up calories and energy. Extra calories that are consumed and not immediately utilized are transitioned to be stored as body fat. This extra energy comes in the form of triglycerides, a type of fatty acid. Triglycerides are derived from, and are later broken down into glycerol and fatty acids. Fat cells throughout the body expand in order to absorb these triglycerides, filling up and storing the excess energy for later use.

Subcutaneous vs Visceral Fat

There are two main types of body fat, subcutaneous and visceral. Subcutaneous is the fat we all know about, and can easily see. It’s soft and squishy, stored right under the skin, and creates those flabs and rolls. Subcutaneous fat can also have some beneficial qualities, serving as insulation and protection.

Visceral abdominal fat is also visible, but not in the same way. Visceral fat grows and wraps around internal organs, creating wide barrel chests and the appearance of a tight midsection. This deep fat develops most when people have large amounts of fat. Because it’s hidden deep in the body, it can be dangerous and have severe health risks. This type of fat can worsen insulin resistance, as well as increase the risk of diabetes, heart attack, and stroke.

Why The Belly?

If you’ve ever wondered why fat around the belly and hips is the hardest to get rid of, the answer is efficiency. Weight is easiest to carry in the midsection of the body, which is the center of gravity. The purpose of body fat is to store energy, so the body wants to use as little energy as possible by carrying it. Our arms and legs swing as we walk, so added mass on our limbs would take more energy to move, effectively defeating the purpose. Our midsection is propelled with the rest of our body, and is the most energy efficient place to store extra weight.


Knowing about fat is key to being able to take control of your health. Understanding its integral role in the body’s functions is a great step in the process of weight management. Working to maintain your optimal level of body fat will help you feel good, inside and out. Create a plan, track your progress, and take your time to enjoy the journey.