Weight Loss Explained, and What You Can Do To Make It Happen

Weight Loss 27 min Read

Written by

Keith Hansen

There is a lot of mystery surrounding weight loss that I want to clear up for you.

So much of this mystery comes from decades of media headlines and diet fads that have culminated in a murky picture of what we need to do to lose weight.

Scientists publish hundreds of weight loss studies each year. Frequently they are taken out of context. Studies are also disproven or found to have been flawed.

In addition to those issues, new studies are changing long-held beliefs. The science of the human body (our understanding of it anyway) is changing all the time.

I aim to give you a modern understanding of how our bodies work regarding fat loss and what you need to do to succeed.

I will simplify many things in this article, so you get the key takeaways. And, when appropriate, I will link to other articles or studies that explain some parts in more detail.

What is your metabolism?

Metabolism is a term used to describe all chemical reactions involved in maintaining the living state of the cells and the organism.

Everything your body does takes energy. We measure energy as calories, and we get them through carbohydrates, fats, and protein. For the cells in your body to stay alive chemical reactions must happen constantly.

Most of the energy your body uses is for your basal metabolic rate (BMR). Your BMR is the absolute minimum energy it takes to keep your body alive. So, even if you spend your entire day in bed as still as possible, you will still burn the number of calories in your BMR.

Of all the calories you burn in a day, about 70% of them go to your BMR. For the other 30%, I will discuss in detail in the section called “More On Calories-Out.”

Calories-in Vs. Calories-Out A.K.A. Energy Balance

The most basic concept regarding weight loss or weight gain is energy balance. Colloquially this is known as “calories-in vs. calories-out.”

If your body is burning more calories than it is taking in, you will lose body weight. If the opposite is true, you will gain body weight. There is no disputing this. 

The First Law of Thermodynamics, also known as the Law of Conservation of Energy, states that “energy cannot be created or destroyed in an isolated system.”

Your body is the isolated system.

If you are not losing body fat/weight, you have not burned more calories than you ate. Your body weight can fluctuate daily depending on your hydration status, carbohydrate intake, and the food still being processed in your gastrointestinal tract (your stomach and intestines, shortened to GI). A month is enough time for measurable fat loss, and those fluctuations should not hide your progress. I’ll talk more about this later in the article.

More On Calories-In

Calories-in refers to the calories that enter your body through your mouth via eating and drinking.

Our bodies get energy through macronutrients: fats, carbohydrates, and proteins. The amount of energy you get from each varies.

  • Fat provides 9 calories per gram
  • Carbohydrate provides 4 calories per gram
  • Protein provides 4 calories per gram

Gram for gram, or pound for pound, fat provides more than two times the amount of energy that carbs or proteins do. This high-calorie content is a crucial reason you need to be *extra* careful adding too much extra virgin olive oil (EVOO) to your salads. Not only is EVOO high in calories by its fatty nature, but it is also highly processed and refined to remove almost anything that isn’t strictly fat. I will discuss why this is important later in the Thermic Effect of Food (TEF) section.

How Your Body Processes Food

When you put food into your mouth and chew it, it is broken down into smaller pieces and mixed with your saliva (spit). Saliva contains something called salivary amylase, which combines with food to help break it down chemically. Chewing food is the first step to getting calories into your body.

Next, food moves to your stomach, where it mixes with stomach acids and other gastric juices (fun words there) to continue to break down.

When your stomach has decided food is ready for absorption, it will pass into your small intestines. The small intestines are where calories will officially enter your body by absorption through the intestinal walls. After passing through the intestinal wall, the food will enter your bloodstream and begin to circulate through your body.

As the nutrients from food pass through your body, cells in need absorb them for immediate use. Excess nutrients will be stored in the body’s fat cells for future use or filtered out through the kidneys to leave the body as urine. The reason your pee will turn a bright neon yellow when you take a multivitamin is because of excess vitamins and minerals.

Just about everything you eat or drink that has calories will make you fatter, if only temporarily.

After your body has taken what it wants from the digested foods in your small intestines, it passes this food to your large intestines. Then, inside of your large intestines, the liquids and water is squeezed out before you poop. At least when things are working correctly (diarrhea, anyone?).

You Need Fat

Your fat is your body’s energy storage system. It exists to ensure you do not starve to death. Your body (metabolism) is in constant need of energy, and it gets most of this through the energy stored in your fat cells.

To help put this in perspective, I’m going to teach you about the Etruscan shrew. It is the smallest known mammal (1.8g of body weight, as much as a paper clip), and it needs to eat nearly constantly. Its metabolism is incredibly high, and it needs to eat 2x its body weight each day to survive. Not only this, but if the Etruscan shrew goes more than four hours without eating, it will starve to death.

To compare this to a human, we can survive for an average of two months without food. There are several accounts of people fasting for hundreds of days. Fat as energy storage was an essential survivability mechanism in the days before you could Uber Eats anything you wanted.

You need fat, but you probably don’t want as much as you have. This article is going to help you even things out.

More On Calories-Out

Calories-out is how much energy your body burns through metabolism. As we discussed earlier, the energy your metabolism needs is about 70% BMR. This is your Resting Energy Expenditure (REE). The amount you need just to stay alive. You don’t have a lot of control over this. Where does the other 30% go? Three areas: thermic effect of food (TEF), non-exercise activity thermogenesis (NEAT), and exercise activity thermogenesis (EAT). These three areas make up your Non-Resting Energy Expenditure (NREE). Combining your REE and NREE, we have your Total Daily Energy Expenditure (TDEE).

a bar graph showing Total Daily Energy Expenditure TDEE made up of BMR, NEAT, EAT, and TEFThermic Effect of Food (TEF)

The TEF is the energy your body burns digesting food and is about 10% of your TDEE. Chewing food up, moving it through your GI tract, shuttling it through your body, and pooping/peeing it out all take energy.

However, not all food takes the same amount of energy to process, and not all food contains the same amount of energy as discussed earlier. We get energy from three macronutrients, and they are:

  • Fat provides 9 calories per gram, and its TEF is 0–3%.
  • Carbohydrate provides 4 calories per gram, and its TEF is 5–10%.
  • Protein provides 4 calories per gram, and its TEF is 20–30%.

The range for each is impacted by the state of the food when you eat it. The more work it takes for your body to get food into a form ready to be absorbed means the more energy required.

This is why something like EVOO can be so easy to overdo when you’re budgeting calories for the day. It is highly concentrated and passes through your GI tract with no resistance. Compare this to eating olives in their whole form—you need to chew the olive, remove the pit, swallow, and then your body needs to process the fruit flesh to separate the fats before absorption. Olives contain a mix of carbs, protein, and fat with 116 calories per 100g. EVOO is purely fat and is 100g of fat per 100g of weight with about 900 calories.

Drinking a soda (carbohydrate-rich) requires no chewing, and it mixes easily with salivary amylase and stomach acids. It passes into the small intestines quickly without much work from the stomach and is readily absorbed.

Pay special attention to the fact that 20-30% of protein calories are burned just to process them. Therefore, protein will help you feel full without putting too many extra calories into your body’s fat cells. One reason proteins have such a high TEF compared to other macronutrients is that a lot of energy is required to break proteins into their base components (amino acids) before being absorbed and used by the body.

Non-Exercise Activity Thermogenesis (NEAT)

Next, we will talk about Non-Exercise Activity Thermogenesis (NEAT). NEAT is the energy you burn once you get out of bed and represents about 15% of your TDEE. Daily activities like walking in your house, fidgeting while in a meeting, taking the stairs, and yard work are all NEAT. NEAT is the things you do to move your body around that are not structured exercise.

Exercise Activity Thermogenesis (EAT)

The final 5% of your TDEE is Exercise Activity Thermogenesis (EAT). EAT is structured exercise like going to a group class, rollerblading, or lifting weights at the gym. Are you surprised that EAT is only 5% of your TDEE? Most people are.

Now please take into account that these percentages are just a starting point.

If you have a highly active job like physical labor, your NEAT will be much more than 15%. If you exercise vigorously for two hours a day, your EAT will be higher than 5%. If you eat a lot more fat than you do protein, your TEF will be lower than 10%.

More On Energy Balance

Your body is finely tuned to exist in homeostasis. You probably remember this word from grade school and that it means keeping different aspects within the confines of an upper and lower limit.

In school, we learned that our body temperature is 98.6°F, but that is just the average. In reality, we are usually a little higher or lower than that number. This is because your body regulates things in a narrow range, such as blood sugar, blood oxygen levels, and the focus of this article—your body fat (energy storage) levels.

There are short-term mechanisms that regulate energy balance, and there are long-term mechanisms that regulate energy balance.

KeY Mechanisms for Energy Balance

A key short-term mechanism that you will be familiar with is stomach fullness.

When your stomach is full, your brain can sense this stretch, and it reduces your hunger. However, it takes some time for the stretch signal to reach the brain and for the brain to tell you to chill out on eating. The time delay between when you’re actually full and when you feel full is why common weight loss advice is to eat slowly.

A key long-term energy balance mechanism is the leptin feedback loop. The hippocampus (a part of the brain) monitors the leptin feedback loop.

Leptin is a hormone secreted by your body fat, and the hippocampus monitors the levels of leptin in the blood. There is more leptin in the bloodstream when there is more body fat, and the hippocampus can detect this. The hippocampus wants to keep your body fat levels within homeostasis, so it tells the brain to make some changes. Homeostasis for your body fat is known as the adipostat. The prefix adipo- stands for “fat,” and the suffix –stat means “the same.” So adipostat means keeping your body fat level the same. The level of leptin & body fat the adipostat wants to maintain is called your body fat mass set point.

When leptin levels are higher than usual, the hippocampus tells your brain to increase NEAT (calories-out) and decrease hunger (calories-in). These directions influence energy balance such that leptin levels & body fat are lowered back to the body fat mass set point.

When leptin levels are lower than usual, the hippocampus tells your brain to decrease NEAT (calories-out) and increase hunger (calories-in). These directions influence energy balance such that leptin levels & body fat are raised back to the body fat mass set point.

At this point, you’re probably asking if the hippocampus is supposed to keep my body fat in check, then why am I fatter than I used to be?

The answer is that it is not a perfect system. It can and does get broken.

In the next section, I will tell you *how we think this happens*.

The Food Reward Hypothesis

I will take the definition for the Food Reward Hypothesis directly from Stephan Guyenet’s website, where I first learned of it:

“The food reward hypothesis of obesity states that the reward (reinforcing, motivational) and hedonic (pleasure, palatability) value of food influence food intake and body fatness, contributing to the development of obesity.”

What does this mean? Most simply, it says that we will overeat things that taste most delicious (high palatability) to us and foods that our body finds particularly rewarding. Thus, regularly overeating leads to obesity.

Hyper-Palatable Foods

Palatability is the nutrition industry’s term for how tasty food is to eat. Our brains are hard-wired to seek out foods that are rich sources of calories that are quickly absorbed. Fats are very high in calories, and sugars are easy for your body to use quickly as energy. Our body’s need for sodium is a key reason why just about everything tastes better with some salt sprinkled on top. The combination of these different elements multiplies the deliciousness of foods from tasty to irresistible.

Delicious foods are obvious:

  • pizza
  • ice cream
  • cookies
  • chips (Doritos are a personal favorite)
  • candies
  • chocolate

Have you ever been completely satisfied with your dinner, maybe even stuffed, and then somehow found room for dessert? The foods that override your stomach’s “fullness” indicator are hyper-palatable foods that lead to fat gain.

Hyper-Rewarding Foods

Hyper-rewarding foods include those listed above, and they also include things that may not be as immediately tasty. However, our body loves them for different reasons. Let me give you two examples you may find relevant.

Beer is something that very few people enjoy the flavor on their first, second or even third tasting. Some people never like it, yet millions of people drink it. Why? Because of alcohol. Once your brain has beer a few times, it begins to associate the flavor with the drug alcohol and develop a preference for it.

This same thing happens with dark chocolate. Chocolate contains certain feel-good chemicals that come from cocoa. Dark chocolate doesn’t have as high of sugar content as milk chocolate, and it doesn’t have the same pleasant velvety mouthfeel, but it does have more cocoa in it. After a few exposures to dark chocolate, the brain recognizes this and begins to change your preferences.

What is the reason for this phenomenon?


A relic of the past

The human body is the result of millions of years of evolution. It was selected through trial and error over countless generations to survive in nature, but about 10,000 years ago, our environment began to change drastically.

Before this point, we needed to capitalize on every single windfall nature provided us. We needed to hoard every source of calories available to us. The name of the game was to get the most calories in for the least amount of calories out. As we discussed earlier, fat is a great energy source, so our bodies strongly prefer it. Concentrated sources of energy like honey are also incredibly appealing to us.

Our bodies needed to take in as much of this energy as possible when available because it could be days, weeks, or months until such a stroke of luck occurred again. Life in the past was often feast or famine.

Ten thousand years ago is when agriculture began to become mainstream. Humans started the shift from a hunter-gatherer lifestyle to a farming lifestyle. This shift led to considerable abundance in the food supply and specializations in our jobs. Not everyone in the community needed to be in the fittest shape possible to run down animals (or outrun them), and some people could live a sedentary lifestyle.

People learned to process, store, and prepare food in new, tastier (hyper-palatable) ways. As a result, food stores made famine less likely, and getting lunch became as simple as going to the market.

Obesity wasn’t widespread during this period, but probably for the first time in history, it became present. Obesity in the past was a sign of wealth because it meant you could afford the most refined, most delicious foods.

In today’s world, studies show that obesity is strongly associated with poverty.

Our environment and the availability of food changed more rapidly than our biology could adjust.

Why did this shift towards obesity occur?

Food science.

Food Science

Food science is what happens when you pay scientists to make food as desirable as possible. Their goal is to drive revenues as high as possible for their employer, and this means tweaking variables to increase consumption to the maximum.

Do you know the Lays potato chip slogan?

“Bet you can’t eat just one!”

Do you know the Pringles slogan?

“Once you pop, you can’t stop.”

Wow. That’s pretty telling, isn’t it?

They have tweaked the shape, salt content, oil levels, sugars, texture, aroma, and colors to make these foods as rewarding and palatable as possible—almost irresistible.

They have also worked to make the foods as cheap as possible.

It’s even harder to say no to low-cost, tasty treats, which is a big reason why obesity is strongly correlated with lower incomes. The food is cheap, delicious, and hyper-rewarding. They have successfully hacked our brains to drive profits.

With all that said, I still haven’t answered the question about why our hippocampus fails to keep our body fat levels low.

Are you ready for it?


Because we live in a world where hyper-rewarding, hyper-palatable foods are cheap, convenient, and easily accessible, we tend to consume them a lot.

Everywhere you go, these foods are readily available and in your face. We are exposed to 4,000 to 10,000 advertisements a day.

This constant exposure to images of hyper-palatable foods means you are consuming more calories than you need pretty frequently. Not only throughout the day but at individual meals as well (and between them).

Excess calories from a meal are shuttled into fat cells for later use. Each time your fat cells swell, your leptin levels rise. The hippocampus tells the body to increase NEAT and to decrease hunger.

Here is the problem: foods that are highly rewarding, hyper-palatable, and cost you little in the way of effort, money, and time override our decreased appetite. Boredom eating is a result of having these foods around.

Instead of using up the extra fat and returning your leptin levels to baseline, they are more likely to stay slightly elevated. This elevated state causes inflammation in the hippocampus. It adjusts to this higher level of leptin, and it can become your new normal. And your new normal is now slightly fatter than it was before. Your hippocampus will now defend this new leptin/body fat level as homeostasis.

What you can do about it

Let’s return to one of the first things we talked about: energy balance.

If you want to decrease your body fat levels, you know you must burn more calories than you take in. Better put, you must take in fewer calories than you burn. This distinction is important for your approach.

You also know that your body uses energy for four different things that comprise your Total Daily Energy Expenditure (TDEE):

  1. Basal Metabolic Rate (BMR)
  2. Non-Exercise Activity Thermogenesis (NEAT)
  3. Thermic Effect of Food (TEF)
  4. Exercise Activity Thermogenesis (EAT)

Recall that structured exercise, EAT, accounts for the least amount of energy used of the four. Unfortunately, the most common mistake I see people make when trying to lose weight is hyper-focusing on cardio and burning calories to lose fat.

Exercise is important and has hugely positive effects on your overall health, happiness, and confidence. I have created an entire company centered around training, but you must first address the calories you are putting into the system if you want to lose body fat.


Because when it comes to calories-out, you have control over about 30% of that side of the equation. Your BMR won’t budge and makes up the other 70% of calories-out.

When it comes to calories-in, you have control over 100% of that side of the equation.

To be successful, you need to address both calories-in and calories-out, and we will talk about that next.

How to Approach Calories-In

If you’re going to tip the energy equation in your favor for fat loss, you first need to know what your TDEE is. TDEE starts with BMR, and then it is multiplied to estimate how many calories you burn per day through NEAT & EAT.

Here is a handy calculator to find TDEE. It is most accurate if you know your body fat level. These calculators make assumptions, and your actual TDEE will not be the exact figure the calculator provides. A calculator provides your starting point. Then, you will use trial & error to hone in on the actual number.

Once you know your TDEE, you want to plan to create a deficit in your energy balance so that the calories your body needs for energy come from your fat stores. A calorie deficit of 500 per day will be your starting point. One pound of body fat is equal to 3,500 calories. So if you successfully create a deficit of 500 calories per day, seven days per week, you can expect to lose one pound of body fat each week.

You probably think this isn’t as fast as you would like to lose body fat, and you may have lost weight more quickly than this in the past.

What I will ask you now is how successful you were in keeping this weight off permanently?

A deficit of 500 calories per day will be your starting point because of homeostasis. Remember that from earlier? Your hippocampus will only allow gradual adjustments in body fat levels, and it needs a steady decrease in leptin levels to adjust to the new normal.

The more drastic the shifts in leptin levels, the more powerful your brain’s response will be, and the more likely you will be to regain any lost weight.

To put this in perspective, the absolute fastest way to lose body fat is to stop eating. Put zero calories into your body. All the energy your body needs will come directly from your stores. You would lose fat very quickly like this.

But how long do you think you can sustain this? And what do you believe would be the odds of you bingeing when you break this fast?

Sustainability is the name of the game.

To maintain the changes in your body, you must sustain the changes to your diet/lifestyle.

You want to lose this fat, and you want to keep it off.

Below are two graphs. They show the difference in your bodyweight levels over 10 weeks and how your body fat mass set point will adjust on each deficit.

This first graph demonstrates a strict, 1,000 calorie deficit diet. Weight loss will be faster in the beginning, but you will be much more likely to fall off of this diet and binge on the weekends. Your weight will shoot back up, and then you’ll motivate yourself to get back on the strict diet when you step on the scale on Monday. You will probably repeat this cycle several times before finally giving up without having lost much weight. This is your adipostat in action.

Does this pattern seem familiar to some of your dieting efforts in the past? 

This is an emotional rollercoaster I want to help you avoid.

Fat Loss 1000 Cal Diet Graph Saved For Web


This second graph demonstrates a tightly controlled diet where you consistently hit a 500 calorie deficit each day. This controlled deficit allows your adipostat to adjust to the changes gradually and allows for more fat loss over time that is easier to maintain. There will always be daily fluctuations but keeping them small helps you stay in control.

Fat Loss 500 Cal Diet Graph Saved For Web


Now that you have a good understanding of why it is so important to start with a 500 calorie deficit each day, it’s time for you to read about how to calculate this number and the best ways to hit it consistently. All of that information is in another article called How to Get Started With Weight Loss Nutrition.

Open that link in another tab and read it after you have finished this article.

How to Approach Calories-out

Remember that the calories your body uses for energy each day come from four different classifications that comprise your TDEE.

Because you have no control over your BMR (the energy it takes to keep your body alive), I won’t focus on that part of the equation.

Instead, I’ll dive into what you can do for each of the other three (TEF, NEAT, EAT) to help with fat loss.

Thermic Effect of Food

To maximize the number of calories your body burns via TEF, you want to choose foods that are as close to their natural state as possible. Eat a diet focused on whole foods that look pretty close to how they came out of the Earth whenever possible. These foods will require more energy to convert to a usable form by your body and help raise your overall TDEE for the day.

The second thing to focus on is increasing your protein intake. Remember that protein has the highest TEF of any of the macronutrients at 20-30%. So for every 100 calories of protein you consume, you will only use 70-80 calories for energy and fat storage.

The importance of protein in your diet doesn’t stop there.

Our Director of Strength Training, Gustavo Ramos, has written a fantastic article centered around the importance of protein, and you will want to open the article in another tab to read after you finish this one.

Non-Exercise Activity Thermogenesis

Remember that NEAT is all of the calories your body burns throughout the day that is not structured exercise.

Take the stairs. Park farther from the office. Walk to your neighbors instead of driving.

A lot of NEAT calories will come from small lifestyle changes.

An important side note about NEAT: NEAT calories suffer tremendously on a crash diet.

When you feel drained, tired, and hungry from a large calorie deficit, you are much less likely to take the stairs. The parking spot nearest the grocery store looks more appealing. Bingeing on Netflix for several hours in the evening seems like a good option.

Creating too large of a deficit through being overly restrictive with your food intake can cause unintended side effects like fewer calories burned through NEAT.

Exercise Activity Thermogenesis

Finally, the portion that you’ve probably focused on the hardest and the section I’ve put last.


When we look at the TDEE graphic above, it tells us that EAT only accounts for 5% of calories burned for the day. So, while yes, it’s true that doing more EAT will account for more than 5% of your calories burned for the day, but that isn’t the whole story.

I wanted to make sure you have a complete picture of everything that goes into sustainable fat loss before talking about the part you probably know the best. So now I’m going to drop some knowledge on you here that will shift your understanding even more.

When it comes to structured exercise for fat loss, your first thoughts are probably about doing cardio—for example, walking, running, and spending time on the elliptical. 

Did you know that cardio isn’t the most effective way to get rid of body fat? 

Crazy, I know.

Cardio can burn many calories, but there’s more to actual permanent fat loss than just burning calories during exercise.

Strength training is a superior form of exercise for several reasons.

Strength training burns calories during your exercise session, after exercise through something called Excess Post-Exercise Oxygen Consumption (EPOC), and it can permanently raise your BMR through increased muscle mass.

Studies have shown that your metabolism is in an elevated calorie-burning state following a circuit-based strength training session for almost two days. If you can get to the gym every other day, then you will enjoy this EPOC burn at almost all times.

Another study showed that strength training added to diet & cardio caused fat loss to increase drastically.

There were three groups in this study: diet-only (group 1), diet+cardio (group 2), and diet+cardio+strength training (group 3).

  • Group 1 (diet only) lost 14.6 pounds of fat in 12 weeks. That’s pretty good and right about in line with our previously discussed goal of 1 pound per week.
  • Group 2 (diet+cardio) lost one more pound of fat than group 1 (7% more fat lost), but they had to do three cardio sessions per week that lasted 30-50 minutes for all 12 weeks. 36 cardio sessions for just one more pound of fat. That’s a lot of work with not too much payoff.
  • Group 3 (diet+cardio+strength training) lost 21.1 pounds of fat in 12 weeks. That’s 44% more fat loss than group 1.

Now, do you see how effective strength training is for fat loss?

The third way that strength training will help you lose more fat is through increased muscle mass. Muscle is metabolically active tissue. It takes energy to keep metabolically active tissues alive, about three times as much energy as fat.

Not only will strength training speed up your fat loss it has a plethora of other benefits:

  • Stronger bones that are more resistant to fracture
  • Stronger tendons and ligaments that are less likely to tear
  • Improved coordination
  • Improved posture
  • Improved confidence

Cardio is excellent and has many benefits like a lowered resting heart rate, improved aerobic fitness, and improvements to your blood pressure.

But when it comes to fat loss, strength training is the best.

My recommendation is to start with three hours per week of strength training as either (3) one-hour training sessions or (4) 45-minute training sessions.

I’ve even written a guide to help you get started with strength training. There is even a Seriously Strong Beginner Program to give some direction. It’s a three-day, full-body program. 

If you love cardio, please do it.

But please do strength training to get all of the benefits from that mode of exercise.

If you don’t love cardio, then you will be pleased to know that you can still lose fat without it.

Keith Hansen

Keith was an All-State wrestler in high school and in 2007 hung up his singlet to attend Florida State University to pursue a B.S. in business management. He wasn't sure what industry he wanted to be involved in at the time, but soon realized after graduating in 2011 that fitness was the ever-constant activity in his life. Keith began studying to become a personal trainer and in 2013 earned the National Strength and Conditioning Association's Personal Trainer certification. After a short stint as a big box gym trainer he realized he wanted to bring something different to Tallahassee. Keith competes in Powerlifting, Olympic Weightlifting, and Crossfit.