The Science Behind Fat Loss…In Plain English

When clients come to me saying that they want to lose weight, what they actually mean is that they want to lose fat. I assist them by providing information, resources, and education to help them understand weight loss...losing fat while maintaining as much muscle as possible, and even losing fat while building muscle.

Some of them want more details about how fat loss happens, so if you're one of those people, this post is for you. I'll explain this as simply as possible, so please be aware that there is a LOT more science-y stuff that I'm leaving unsaid. If you're a biology teacher and you want to add your two cents, please do so 😊

The body carries two types of fat: visceral, and subcutaneous.

Visceral fat is the "deep fat" that surrounds your organs. It's the more dangerous of the two, and researchers have made connections between high levels of visceral fat and higher risk of cardiovascular problems, insulin resistance, glucose intolerance, and even different types of cancer. On the positive side, visceral fat is quick to respond to changes in diet and exercise, so this is always the kind of fat that you will lose first.

Subcutaneous fat is found directly beneath your skin...the dimples, rolls, and "soft" look that cover your muscles and prevent you from looking "toned". None of us like subcutaneous fat, but it's not considered "dangerous". Some subcutaneous fat is good and necessary for survival. You'll notice fat loss in your face and outer limbs before you'll notice it in your hips, thighs, and stomach. That's because we typically lose fat from the bottom up and from the top down. Your personal "last place" to lose fat will vary according to genetics, but it will be somewhere in the mid-section of your body (stomach, or hips/butt, or thighs). Plus, consider that you usually start out with more fat on your thighs or belly area than you do on your although to some extent, you do lose fat from all over "at the same time", there's more to lose in your mid-section.

You cannot target the type of fat (visceral or subcutaneous) you want to lose with various types of food, exercise, or products. Your body will get rid of the fat in the God-ordained sequence....visceral fat first, and then subcutaneous fat. Further, it's generally accepted as fact that you cannot target the location of subcutaneous fat loss. I say "generally accepted" because there are some studies that have shown that intense interval cardio (HIIT training) is best for targeting "stubborn fat". But just doing HIIT doesn't mean that you can skip the fat loss in your face and burn it off your thighs instead.

So, when we say "fat loss", what are we losing, and where does it go? The simplest explanation is that fat cells don't die, they shrink. So you retain the same number of fat cells but they get smaller. From Mayo Clinic's website: "...fat is basically stored energy. Your body converts fat to usable energy for your muscles and other tissues through a series of complex metabolic processes. This causes your fat cells to shrink. These metabolic activities also generate heat, which helps maintain your body temperature, and waste products. These waste products — water and carbon dioxide — are excreted in your urine and sweat or exhaled from your lungs."

Although it would be nice if we peed out our fat cells, that's not technically correct. It's true that some of the waste products from this metabolic process are urinated out...but believe it or not, over 80% of the waste is converted to carbon and breathed out.

So **how** do you shrink those fat cells? See the quote from Mayo Clinic above regarding converting fat to usable energy. If you don't provide your body with enough energy in the form of food (this does not mean "starving"'s simply calorie restriction, or "dieting"), it will have to rely on its fat stores for energy. Exercise helps by increasing the need for energy, but it also sets off a bunch of other really cool processes that can assist you in shrinking your fat cells and building your muscles. So, calorie restriction and exercise? That's all?

Yes. Stick with the basics. Sleep, stress, hormones, hydration, food choices, macronutrient ratios, and more all play into the equation, both directly and indirectly. But diet and exercise are the MVPs.

This stuff is always fascinating to me, but I'm curious...what do you think? Do you like to learn about the "why"? I like to talk about the "how", the practical application, but sometimes knowing the facts and the biology behind it all can prevent frustration during the fat loss process.

So please don't get frustrated. Fat loss (fat cell shrinkage!) takes time, and you can't cheat the laws of biology set in place by the Creator.